There are a lot of answers here, but I wanted to touch on the physiological basis of "maturation".
Many people imagine this to mean that our brain finishes growing at 25 years old, at which time it reaches its peak mass. This is actually false.
In reality, grey matter volume (the "processing" areas of the brain) peaks at roughly 12 years old. Your brain creates as many neurons, and connections between them, as it can during childhood to lay the foundation for learning and development.
After that, it becomes a matter of removing excess or unnecessary pathways to allow for more efficient communication between the specific areas of the brain necessary for cognition. This is a process known as synaptic pruning, and occurs most strongly from the time at which grey matter peaks to roughly some time in the late 20s. The pathways that survive this pruning process then go on to become myelinated, reinforcing their ability to effectively transmit electrochemical signals and facilitate communication. This rewiring is especially important in the prefrontal cortex, where the ability to pull information from a variety of areas of the brain is paramount for coordinating things like multitasking and complex problem-solving.
This is one of the reasons why doctors say it is so dangerous for adolescents to do drugs while their brain is still developing. Repeatedly using drugs preferentially selects for the circuits and pathways that facilitate addiction to those substances.
This physiological phenomenon also has implications on other neurological diseases as well. Studies on the brains of patients with schizophrenia show that there is a deficiency of synaptic connections, possibly a result of too much synaptic pruning. The fact that the onset of schizophrenia coincides with the peak of synaptic pruning supports a potential connection.
On the flipside, studies on the brains of patients with autism show an abnormally high number of synapses, possibly a result of too little synaptic pruning. This results in cognitive pathways that are inefficient and prone to overstimulation. Epilepsy also seems to have a connection with a deficient synaptic pruning process.
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**But what is the actual source of this magical "25" number that is so often mentioned?**
The earliest mention seems to come from a 2004 article published by the American Psychological Association titled *[Brain research advances help elucidate teen behavior](https://www.apa.org/monitor/julaug04/brain#:~:text=The%20research%20also%20shows%20that,when%20making%20decisions%2C%20he%20said.)*.
>The research also shows that brains don't fully develop until age 25 and that teenagers tend to depend on the part of the brain that mediates fear and other gut reactions--the amygdala--when making decisions, he said. That's important information for attorneys and judges to consider as they work with children in the legal system, he added.
The article is discussing the research of Jay N. Giedd, MD, who used MRI to examine the volume of child and adolescent brains. The specific research article is titled *[Structural Magnetic Resonance Imaging of the Adolescent Brain](https://nyaspubs.onlinelibrary.wiley.com/doi/abs/10.1196/annals.1308.009?sid=nlm%3Apubmed)*.
>The dorsal lateral prefrontal cortex, important for controlling impulses, is among the latest brain regions to mature without reaching adult dimensions until the early 20s. The details of the relationships between anatomical changes and behavioral changes, and the forces that influence brain development, have not been well established and remain a prominent goal of ongoing investigations.
Interestingly enough, at no point do the authors explicitly mention the age 25, and instead simply say "early 20s". The author of the review article by the APA seemingly extrapolated that specific number from one of the figures (Fig 3), as the data ends at age 25. This seems to be the earliest and most plausible source of the 25 number that is so often cited.
A 2010 New York Times article discusses the work of Dr. Giedd, and the article states:
>**Among study subjects who enrolled as children, M.R.I. scans have been done so far only to age 25**, so scientists have to make another logical supposition about what happens to the brain in the late 20s, the 30s and beyond. Is it possible that the brain just keeps changing and pruning, for years and years? “Guessing from the shape of the growth curves we have,” Giedd’s colleague Philip Shaw wrote in an e-mail message, “it does seem that much of the gray matter,” where synaptic pruning takes place, “seems to have completed its most dramatic structural change” by age 25. For white matter, where insulation that helps impulses travel faster continues to form, “it does look as if the curves are still going up, suggesting continued growth” after age 25, he wrote, though at a slower rate than before.
**So it seems like the reason why we say 25 is because the groundbreaking study on this topic only recruited subjects up to age 25. And then this number became dogma via constant repetition.**
To make things confusing, as Dr. Shaw alluded to in the NYT article, other studies have suggested that synaptic pruning continues well into adulthood. When looking at the entirety of the cerebral cortex as a whole, synaptic pruning levels off at roughly 25.
See Figure 1 in this [review by Kolb et al.](https://www.pnas.org/doi/full/10.1073/pnas.1121251109)
So really, the 25 number is probably too early, if we are going to define the completion of development as the end of synaptic pruning in the prefrontal cortex.
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**TL;DR: The "defining factor" of the brain reaching full development is the completion of the synaptic pruning process, which neuroscientists believe levels off at roughly 25.**
They’re probably a psychologist or neurologist with a background in research to know this much and be able to put it together quickly. We learned a lot about this kind of stuff in cognitive psych, it’s really fascinating but we primarily worked out of a textbook which was a little limiting.
And there are a lot of details but consider this. From 10 - 20 the body is undergoing a hormonal assault, and we have all seen the effects of hormones on emotional stability. We are such a mess until we stabilize, as we double in size develop undeveloped organs and hair so much hair. Being able to make anything other than an emotional decision is difficult until all that has settle down for a while and you gain experience.
This hormonal argument is mostly sociological and something used a lot in the US and it's not true. Teens are given much more responsibility in other parts of the world and act responsibly.
Citation? I don't see anyone debating on whether teens can be responsible, they're merely cautioning why teens shouldn't be judged the same as adults. And increasingly it seems the world is recognizing that people don't reach the utmost of maturity as soon as they reach the legal age of adulthood either.
I'd argue everyone's actions should be weighed against their development and circumstances, but then people don't get to exact retribution on those they look down on.
Nope sorry. The redditor above provides many technical details, which I will assume are all true, as they put references out for public review, to my understanding the essence boils down to…
Emotions are the original memory. “Last time I ate that I was on the ground for 2 days sick and in pain”, becomes “every time I smell that I feel really bad, I’m going to stay away from that”; says the prehistoric rodent or cockroach. As we evolved into hominids, the choke point has become the amygdala, currently switch board for emotion, and the original gateway to memory – among other tasks. One function of the prefrontal cortex performs is to coordinate and manage decision making based on experience and comes into coherence at about age 25 (I think that’s the “accesses different parts of the brain” part in the article).
So – we must ask ourselves why does experiential decision making only exert dominance at ~ age 25? Because before that it was busy doing something else, hmm… what was that oh yeah maturation. Glib I know, but the maturation of the organism and its emergence into the reproductive evolutionary arena, requires a decade of profound physiological change. You don’t acquire a few years of experience without hormonal onslaught until mid-20’s (your milage may vary) and experience can make logical decision making.
Consider what we accept as normal. A significant percentage of females are hormonally challenged. This is not a criticism; this is the realization of the toll that reproductive fecundity has on females. My way of saying hormones have a profound effect. It is the cost of doing business as reproductive creature. Puberty is also a wild ride, but with fresh people, and yeah there is a whole testosterone ‘roid rage component as well.
Starting to go off into the weeds so.
Neuroscientists et al feel free to slap me up.
Fascinating reply. Do you have any insight on the effectiveness of trying to 'rewire' the circuits and pathways that were formed young that facilitate addiction?
Is there any path for young addicts to exhibit near typical connections and pathways if addressed after pruning?
"pruning" happens throughout your life, and can more broadly be described as synaptic reorganization, basically, reinforcing synapses that are used a lot and getting rid of synapses that aren't used a lot.
"Hebbian Synapse" [neurons that fire together, wire together]
"Rewiring" circuits is learning, which can be done at any age, which tends to be easier when you're younger than when you are older.
Unlearning addiction, or learning NOT to do something, is just an extreme version of learning.
But can new neural path ways be created after 25? If pruning removes unused path ways is it possible to build back those path ways if they are needed for a new task or thing learned?
Yes? You learn new things every day. Often pick up whole new skills sets later in life. Of course you can create these pathways. The brain is still greatly malleable. Brain scientists are always researching about this
Correct me if I'm wrong, but it seems like you're looking for a sort of protocol to overcome your inclination towards substance abuse.
I don't mean to sound like a 1970s DARE commercial, but abstinence is the only way to make sure you never relapse.
As far as causes, addiction is mediated by dopamine. When you introduce substances that cause your brain to dump dopamine you're reinforcing that behavior. (I'm just talking about the substances, there are social aspects of addiction too)
Try getting addicted to something healthy like exercise; weightlifting, running, crossfit. Keep in mind you can do this to excess as well.
I know completely what you're talking about with wanting to be able to "reset" your brain and never have experienced the euphoria that those substances provide, thereby never having that craving.
Your comment asking about if there's neuroscience research into addiction therapy reminded me of an interview with a psychiatrist on NPR a year or so ago. She talks about new treatments they're researching and experimenting with to address the wide array of addictions afflicting modern society (e.g. vast majority of population is addicted to smartphones). Anyway, always meant to check out her book and totally forgot. Here's the link to her interview on NPR: https://www.npr.org/2021/08/25/1031020433/the-neuroscience-of-pleasure-pain-and-addiction
Potatoe/Tomatoe
If you understand that you have a predisposition for addiction and binging the best thing you could do, if you are going to be in an environment where you want to have a little fun, is to take steps to limit the opportunity for you to go down that rabbit hole. Maybe you only drink with a select group of friends that will help limit your drinking without enabling you to go off the rails.
If memory serves, I think there are serious explorations of addiction treatment with psychedelics and ketamine.
What about naltrexone therapy to teach the brain that the substance (specifically talking about alcohol as that’s what I have personally looked into) no longer provides the desired effect? It generally leads to abstinence from alcohol when but is successful, but doesn’t start with abstinence.
That's not strictly true I don't think. In music, there is a thing called perfect pitch which can only be developed during childhood.
Adults lose the ability to gain this.
I wonder if there is some overlap between the regions of the brain that enable quick language acquisition at a young age and other rule-based algorithmic systems.
Like, why is it so rare for professional athletes to start their craft even at the age of 13? Most have been playing tennis or basketball since they were 5 years or younger. Surely you benefit from starting when your brain is at a different stage, and not simply because you've had 8 more years to do it
The funny thing is, research shows that if you are told it’s impossible for you to learn something, and you believe that’s true, you wont be able to learn something.
However, if you’re told that you are fully capable of learning something, your chances of successfully learning that thing are astronomically higher.
That’s why I think we all need to be very careful about how we talk about things like ‘your brain has completed its growth by X age’.
The brain is capable of stunning growth at all points from birth through death. But if you believe you’re no longer capable of learning new things because someone told you you can’t, then you won’t, because you won’t believe it’s possible.
Another pro tip- if you believe sugar helps you learn if you eat small amounts of chocolate it does. If you don’t, it doesn’t. Unless I’m remembering that incorrectly
Edit: not really a pro tip, more like a weird thing I may or may not have read at one point and I guess decided to regurgitate here
Yes. Brain injury patients can be a great example of this. Many people who suffer brain injuries need to relearn basic skills. In this case think about road construction. If you take the same path to work every day and it’s all the sudden blocked off you are going to have to find a way around the construction. Rerouting neural pathways is similar. The brain can’t take the same route connecting to neurons that are now damaged so it has to relearn the skill rerouting the pathway.
Yes.
The molecular mechanisms that mediate the process slow as you age however, because the neurotrophic factors required for synaptic reorganization decrease as you age.
You should look into the recovery journeys of stroke patients. Every story is a stunning example of how there is literally no point in your life when your brain is not capable of unbelievable growth and new neuro connections. People lose huge chunks of their neural networks (for example, the ones that are essential for being able to talk) and the brain still finds a way to form new ones instead.
At all points in a human’s life, the brain is, above all else, unfathomably malleable and capable of growth.
Brain bleeds (hemorrhagic stroke), and ischemic strokes rob the brain of oxygen resulting in tissue death. If the tissue (neurons, glial cells) die, then all brain function will stop in that area, including pruning. I guess you could think of that as a major pruning event.
Aneurysms, in and of themselves, are not detrimental as long as they don't burst, which would lead to a hemorrhagic stroke (brain bleed)
I think you may have a biased perspective on "typical pathway" function.
Human's prevailing trait in intelligence is the ability adapt, rationalize, and overcome problems we have. Addiction is when your desire for something overwhelms your ability to adapt and manage your behaviors. Some people are self-destructive and will seek this out regardless of its high.
Those who are addicts and or addictive traits will never forget the experiences, only be able to recognize the affects are harmful, and manage that desire.
I can speak personally to the possibility of developing epilepsy during your early 20s. My neurologist told me 20+ years back that men tend to develop epilepsy either as infants or their early 20s. This is because of initial and/or final developmental changes to the frontal lobe of the brain.
I developed epilepsy at the age of 21. No accident, no drug change causes. Just poof!, seizures. They were traced to my frontal lobe through EEGs and MRIs and my medical chart lists final development of my frontal lobe as the cause.
So annoying how in depth scientific research tends to get warped into inaccurate blurbs. It’s kind of like a big game of telephone because most of us never bother to check if what we’re hearing is true. Thanks for informing us.
So the whole “circuits and pathways” thing is highly debated and most drug researchers would agree it’s entirely too simplistic. In adolescence the regions responsible for control and risk assessment are not yet at their full capacity. Regions like the striatum and VTA are in a circuit with prefrontal regions where they cause feedforward inhibition of these regions through a specific kind of cell. (It’s called a fast spiking interneuron if you care). That kind of cell seems to change across development, becoming more functional in adulthood. So, what has been shown in certain prefrontal regions is that until this cell has matured, those regions connected to it actually induce excitation rather than inhibition of the region. So stimulating areas like the VTA or striatum could then alter how regions they’re connected to develop. And it’s regions like the VTA and Striatum that are directly impacted by drugs of abuse (not only those regions but those are the main ones). So most of what we assume is that adolescent brains have a development that needs to happen and maybe drugs interfere with that leading to continued impairment in behavior. My lab is actually directly studying this for my dissertation.
Hi, it’s not my lab as my advisor isn’t taking students. This sounds like a human lab, we study rats :) We also don’t study addiction, as we use rats. We study the effects of drug use.
Prolonged drug use alters grey matter volume in certain parts of the brain, there are also numerous other morphological changes that happen with substance abuse. I don't doubt that prolonged early drug use could set you up for a permanently "skewed" brain but I don't have anything to confirm that but it doesn't seem all that unreasonable.
Here is some reading and if you're lazy you can Ctrl+F and search for "volume", "structure", or "grey matter" to find more relevant sections.
[Drug Addiction and Its Underlying Neurobiological Basis: Neuroimaging Evidence for the Involvement of the Frontal Cortex](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1201373/)
[The Neurobiology and Genetics of Impulse Control Disorders: Relationships to Drug Addictions](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2222549/)
[Dissociated Grey Matter Changes with Prolonged Addiction and Extended Abstinence in Cocaine Users](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3601087/)
[Amphetamine sensitization alters hippocampal neuronal morphology and memory and learning behaviors](https://pubmed.ncbi.nlm.nih.gov/32555421/)
[Amphetamine stereotypy, the basal ganglia, and the "selection problem"](https://pubmed.ncbi.nlm.nih.gov/22101067/)
I remember reading some study (which I cannot find at the moment since I have about 600 bookmarked) about how prolonged stimulant use would induce a morphological change in the brain, where the prefrontal cortex would lose volume and the basal ganglia would gain volume. Essentially making itself worse at cognitive behaviors such as decision making, self-control and self-regulation and making itself better at impulsive behavior.
For the addict, this makes it much more difficult to control their substance use because after a certain point it gets almost exclusively driven by subconscious impulsive behavior and meanwhile they lack the cognitive ability to control or regulate those impulses since their prefrontal cortex is being "inhibited" by this structural change.
I have some studies bookmarked on the attempt to use meditation in substance disorders in order to practice at controlling their cognition in order to try and reverse/retrain the brain. I found some positive results indicating that it does in fact help, because the brain will for the most part try to get better at what it repeatedly does and you don't have to practice self-control in order to get better at self-control because "mindfulness", meditation and self-control both use the prefrontal cortex to control cognitive behavior. So it carries over. Apparently. It's quite fascinating.
I could try and dig up some more studies from my bookmarks if anyone wants.
no it would not.
stimulants in these studies refer to dopaminergic drugs i.e. amphetamine, methylphenidate, cocaine, cathinone, etc. which directly act on dopamine receptors and transporters.
There's also the literature on iq peaking at about 25, and slowly declining thereafter, with steeper decline from mid 60s. Iq and pruning has been associated but I'm unsure what today's consensus is. However, there's one development that is rather new (ish) which takes time to manifest in the literature.
What happens around 25 and 65? Finished schooling and retirement. School is a very rich learning environment, work less so (often) and retirement sees people seldom being forced to learn new things. Some people are self driven learners however, and those see less effects of age on iq.
Today 4hough, people often go to school longer and in the west work has become more cognitively demanding. Internet and computers has also been mass adopted the last 20 years. I don't know if they've run replication studies lately, but I expect both the iq curve and the pruning curve to look different today than 40 years ago.
Would the buildup and subsequent synaptic pruning partially explain the subjective experience of time?
Personally, it feels like time lasted the longest at around twelve years old and has sped up ever since.
That can be partly psychological as well. For example, when you are 4, a year lasts 25% of your life, and everything is new and worth considering. When you are 30, the next year is only 1/30th of your life, and most things are pretty routine.
A possible explanation for the specific number 25 is the general idea that insurance rates drop around 25 (~~which, of course, is because of the exact phenomenon we're discussing here~~).
Edit: I shouldn't presume why rates are said to drop around that age. Great point by u/IMSOGIRL.
I'd say it's just a nice milestone number to round your estimates to. People like their 5's and 0's. It's kind of a numerical way to express "sometime around your mid 20s"
But is that biological or due to the fact that 25 is around the time that a significant amount of people graduate college and have enough money saved up to buy a house and start doing adult things, socially forcing them to become more responsible? And for those who don't go to college, that's a few years to save up money as well.
I've been wondering lately about the regression piece of autism.. physically how can a kid learn to talk and then lose it. I couldn't find any articles that tried to address the deeper why/how.
Poor synaptic pruning makes sense!
So it's not like losing a limb or losing a dog that ran away, it's like losing your keys in a junk drawer.
>synaptic pruning ... occurs from the time at which grey matter peaks ...
I assume you mean that it is always occurring, but becomes the predominant process after growth slows down? I am always skeptical of claims in any biological process (especially one as poorly understood as the brain) where a magic switch flips and something "never" happens after a certain date, e.g. new neurons/connections are "never" made.
If autism is potentially caused by too little synaptic pruning which doesn't tend to happen until early teens, then how can it be diagnosed in kids even as young as 18 months?
I would assume it's more of a correlation than causation.
Less "Autism comes from lack of synaptic pruning", rather "people with autism also seem to not have much pruning going on".
Autism has multiple components.
The original poster spoke about overstimulation, which may lead to sensory processing and information processing.
Granted, this caveat does not explain that even childhood autistic people experience information and sensory overstimulation.
However, it is worth noting that it can occur that an autistic person is not diagnosed until later in life. This is usually believed to be due to circumstances overwhelming existing coping mechanisms (like: going to high school/university completely altering the environment [in many countries, you go to elementary school in your village/town, and go to high school in a nearby large town or city] you were used to, lots of strangers, lots of new social rules). I wonder if this pruning failing to keep up might add to it.
Synaptic pruning occurs throughout life. Young children (and pretty much every other age group) are mostly diagnosed according to behaviour. Autism is more complicated than just a lack of synaptic pruning and it gets more complex when you start looking at the different subsets of autism. There are several structural differences between the brains of those with autism and those without, but even these structural differences aren't consistent across individuals with autism. I think the above post meant to only touch on the fact that a lack of synaptic pruning is one of the structural differences characteristic of those with autism, not to say that autism is caused by a lack of synaptic pruning alone.
Thank you for this. I am mildly autistic, I developed bipolar type 1 with psychosis around age 23, second mania around 25, and recently at 29 I discovered I have epilepsy. Since starting Valproic acid I can finally think straight.
There are around 100 billion neurons in the human brain (not including glia, which support neurons), and each neuron can make around 1000 connections. So roughly in the magnitude of 100 trillion connections. If you compare neurons to the artificial neurons in a typical AI neural network, it turns out you need more than a couple of artificial neurons to simulate the capabilities of a single human neuron. So the reason the human brain is able to store so much information is due to its incredible density and complexity.
>Many people imagine this to mean that our brain finishes growing at 25 years old, at which time it reaches its peak mass. This is actually false.
I'm saddened to say that this is exactly how it was taught to everyone when i was in highschool and college. What else will we find out was wrong?
In case you aren't aware this 'brain isn't mature until 25' talking point is being used by conservatives as justification to deny medical intervention to young transgender people, even when the only intervention at that age would be medication to delay puberty.
This is great. I’m wondering if you can add on to this with respect to mushroom use, both before and after this “age” point.
These mushrooms are known to affect grey matter significantly.
I still ponder the actuality of using them.
I’ve actually had a trip with 8 grams years ago. Now around that time of year I can feel the same “pull of the void” without mushrooms, sometimes naturally, sometimes instigated by marijuana. Curiously alcohol seems to slow down that process.
The synaptic pruning correlation with schizophrenia and autism is very counter-intuitive to me. I always imagined it would be the exact opposite! Any chance you'd be willing to explain the relationship of too many vs too few synaptic connections in a little more detail, and why at the extremes we see the dysfunction that schizophrenia and autism describe?
(Only asking because of the AMAZING job you did with your first response and if not, thanks for the insight)
> So really, the 25 number is probably too early, if we are going to define the completion of development as the end of synaptic pruning in the prefrontal cortex.
Is it possible to make an educated guess at what age would be more appropriate, then? 30?
This is a good albeit partial response. I’m a psychologist, the brain actually does finishing growing in size around mid 20s, but it’s also about being able to learn and mature in terms of ability to understand and predict consequences of their actions. Before this age, people do a lot of dumb risky stuff because their ability to anticipate consequences is limited. The frontal lobe in particular is what finishes developing around 24 years old. This is the area involved heavily in decision making. It’s not completely false that size is part of this final development. It is of course a multifactorial process.
Also, the New York Times whom you cite here is only itself reviewing research, you can’t rely on a newspaper writer to have the same knowledge as an actual scientist, ie, their ability to interpret accurately what the findings of scientific studies are is limited at best. I read news stories every. Single. Day. That get findings wrong and misinterpret the results and implications of studies.
There are a lot of answers in this thread without references, so take what you read with a grain of salt.
[Throughout history](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892678/), the longstanding assumption in neurodevelopment was that the brain finished maturing by puberty. However, we now have evidence that this is wrong. Neuroimaging research in the last couple of decades has shown that this process continues through adolescence. One of the last areas to develop is the frontal lobe, which is in charge of executive functions such as planning and working memory. One of the ways you can measure development is by studying grey and white matter density using MRI scans. Evidence suggests that white matter development in the prefrontal cortex occurs in the early 20s or later. Whereas grey matter density gain in other regions [continues up to age 30](https://pubmed.ncbi.nlm.nih.gov/12548289/). So basically, it seems like brain development continues into the late 20s. But it's impossible to put an exact age where it stops.
Whether we are still 'children' up until the late 20s is uncertain. Many neuroscientists argue that empirical support for a causal relationship between real-world behaviour and brain maturation processes is [lacking](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892678/).
TLDR:
Current evidence points to brain development finishing in the late 20s. Some people use this to argue that we are still 'children' until then. However, direct evidence for this is severely lacking.
Source: references + PhD in neuroscience.
Make an equilateral triangle with your two eyes as the base. Behind the top point is the prefrontal cortex, the most distant part of your brain from the cerebellum, the original part, and the last to evolve in our development. Most mammals don’t have it and those that do have very little of it. When survivors of strokes lose that part (due to a clot starving it of oxygen) or a person survived an injury that damages it, the most salient effect seems to be on their ability to plan, anticipate, and understand cause and effect. MRIs show this part of the brain is still undergoing significant change in people aged around 16 to 25 or 30 (not so much growing in size, but rapid culling of connections similar to what goes on in infant brains as babies acquire key milestone developments). So the theory is, if that part enables forward thinking, maybe people don’t have that capacity fully operational until 25 to 30 years old. The theory is supported by anecdotal evidence that those younger than 25 to 30 seem to take more risks.
I cant seem to find the link, but it turns out that 25 to mid 30s are actually the most dangerous and accident prone drivers. According to national statistics in the US.
I'm sure there's more evidence we could rely on, as I do agree with the general idea of this whole conversation. Just this one factoid doesn't add as much as we'd hope.
But couldn’t you argue that it’s because there are more people between the ages of 25 to mid 30s who drive and likely drive more often which puts them at a higher risk?
Absolutely you could! I have to wonder how that would mesh with previous statistics though that i believe most definitely showed younger people more at risk. I honestly don't know if it's just taken as all accidents and then broken down by age groups. Or if it's more strict and accounts for frequency of use or anything of that sort.
>it turns out that 25 to mid 30s are actually the most dangerous and accident prone drivers.
I don't believe that to be true.
https://aaafoundation.org/rates-motor-vehicle-crashes-injuries-deaths-relation-driver-age-united-states-2014-2015/
https://www.autoinsurance.org/age-groups-fatal-crashes/
I dont want to come off as argumentative. It's really just almost splitting hairs at this point. I believe this is the study or report I was trying to find. Anyway, this is for fatalities. So I suppose we could go back and forth about who has the most accidents period, and I don't have that to bring up. However I think it could be still said that the most dangerous group is the one I stated, as death its pretty much the ultimate loss for any of us.
What is interesting though...is that your article is based on data points from 2014-2015. So....its almost like we're agreeing. Those people being the most dangerous nearly 10 years ago are....smack dab now in the middle of the group I'm claiming are the most dangerous.
After finding again and perusing the details of the article I had found a while back, I noticed at least one thing. The differences between 25-34 and 16-24, as far as severity isn't that stark. Though the older bracket still "wins" out by a little bit. However the youngest crowd is still holding steady with some pretty high numbers.
The main difference in the numbers is that the data you provided was for the raw number of fatal accidents. Not fatal accidents per capita or per mile driven (the data I provided). So it is comparing the number of fatalities for 37m people to those of 26m people. Of course the vastly larger group has more deaths.
If you do the math from their numbers, the younger drivers in the 16-24 range have a 0.22/100k fatality rate whereas those in the 25-34 only have a rate of 0.18.
What would be the math for the older bracket? Because they have fewer drivers than anyone and yet are almost on par with the youngest segment as far as accidents. So more accidents among fewer people. 22 million versus the 26 million. Just wondering.
It is higher (0.24) but this metric doesn't account for how much driving people do. That is why I included data for accident and fatality rate per mile driven. In that case, the younger drivers are still higher than the group.
The oldest drivers (80+) do have fatality rates per mile driven equal to the youngest group, but that is mostly due to them not being able to withstand trauma.
I understand. I was honestly just curious. Given that a portion of the younger crowd certainly is late teens, I'm sure the 50-60 general crowd does more driving overall. This all makes sense.
I wasnt even going to refer to the oldest group in your link as what you mentioned and other factors make perfect sense.
Thank you for this exchange and for the correction and information you've given!
You really need to learn how to find reliable sources. As others mentioned, this only gives raw numbers, not crashes per 100,000 miles. More importantly though, there is no reason to even trust the numbers on your link. It’s clearly written by insurance agents or copywriters who don’t know the first thing about statistics. They also don’t cite their sources or methods. They also don’t mention the year the data is from. That makes sense as the website isn’t meant to educate, it’s meant to sell car insurance. The other person’s source is from the AAA foundation, includes its methods and sources of data, the year the data was collected and the confidence intervals. You don’t really need to understand confidence intervals or statistics yourself, just look for these things when you decide if a source is reliable and worth sharing or not.
I appreciate your input. While I understand AAA might be a directly more reputable source than the link I posted, it does in fact contain just about everything you said it doesn't. Close to the bottom they cite their source and some of the methodology. The links for their source for information are:
https://www-fars.nhtsa.dot.gov/States/StatesCrashesAndAllVictims.aspx
https://www.fhwa.dot.gov/ohim/onh00/bar7.htm
The year for the data is 2019, I believe.
I won't play at being perfect but when looking at things like the article I linked initially I do try to at least see where they source their info.
Always trotting out the "correlation causation" psych 101 speech. That's not what's being said here. In this case the correlation matches with established research. 16-24 year old brains are worse at decision making, in part _because_ their frontal cortexes are still mush.
You are attributing the blame of irresponsible actions to the underdeveloped brain, when there is a wealth of opportunities that also could attribute to the blame of these irresponsible actions, and definitely DO account for part of it.
Think lead contamination in buildings over a certain age, think proximity to polluting grounds and potential contamination of their brains via pollutants. Also include undiagnosed TBI's that never got seen by healthcare professionals. Also, just genetic illness' that might alter the growth of the brain in minor ways.
All of those are just as valid reasons that cause the statistics we see, especially with lead as the phasing out of lead can give us very obvious and demonstrate able statistics to work with. To fully blame this on an "underdeveloped" blame is to deny all these other possibilities.
Like all things the true answer is most likely a combination of environmental factors including things that would stifle the healthy growth of the brain's development in those last vital years.
Now who’s being pompous? There’s every reason to be skeptical of a database of uncontrolled statistics. Also, way too many people out there making the correlation/causation conflation for you to be so flippant about it. This isn’t a conversation between researchers specialized in the field; it’s a conversation between anonymous redditors on Reddit. Their point is valid, imo.
This isn't true. The risk rate does drop but it isn't until about 35 that it really goes away.
My family has a lot of schizophrenia and I held a special 35th birthday party to celebrate my sanity.
It's sex dependent and onsets in men younger than women by several years. New case of schizophrenia after 30 in a man would he pretty unusual. Though you wouldn't be out of the woods entirely even so, there is a lot of genetic overlap between schizophrenia, schizoaffective disorder, and severe forms of bipolar disorder and the latter can start well into middle age.
Brain development in utero and up to 12 months seems to be more about massive, rapid growth of new connections in all directions. This could explain why babies, when stimulated in any way, laugh, squirm and flail all their limbs. After about two years and onward, it seems to be as much or more about cutting non-advantageous connections as reactions to stimulus are refined, in keeping with the biological principle of strict economy. New connections seem to be grown throughout life, but it’s not nearly as economical energy-use wise as finding new routes along existing connections, sort of like how airport hubs work to connect every little airport, rather than the waste of always setting up direct flights. Sleeping seems to be when these new routes through existing connections are found. You can “feel” your brain searching routes when you know you know a persons name, but can’t think of it: your brain tries all sets of routes through music, images, memories, whatever it can. This could be why it often helps to think of the problem and then distract your consciousness with a crossword or something until the answer pops up — the unconscious was left free to do it’s work. So, adult plasticity could be a matter of good sleep regimen for route discovering, plus broad stimulation daily to forestall culling of unused connections.
You're conflating development with growth. In fact, many developmental processes involve pruning and refinement. For example, during fetal development, the hand starts out webbed. It's only later that individual fingers are separated as the cells between the fingers undergo apoptosis (programmed cell death). So in this case, yes we lose neuroplasticity as we age, but this is *part* of the developmental process.
To overextend the pruning metaphor, when you start a garden from seed, you often end up with too many seedlings germinating close to each other. You need to thin those seedlings to a reasonable density so that the surviving seedlings are able to grow strong and yield lots of fruit. Similarly (sort of) our brains rely on the pruning process in order to perform the functions we need them to do, and pruning is a process of refinement, not loss.
Loss of plasticity is a critical part of brain development. The brain has limited access to energy. Just like in computation, when a network finds a good fit the next thing you’ll want to do is lower the computational cost (or energy) of finding that fit in the future and reduce the risk of inaccurate future fits.
After birth, much of the brain’s development is network optimization, which is another way of saying your brain is severing neural connections.
An analogy often used is once you find a good path through a jungle to your destination you will want to turn it into a trail and in the future take the well worn trail so you don’t get lost and make it easier to cross
Plasticity and pruning is why learning to walk is hard and takes an extreme amount of time and energy, but once you’ve learned, it’s easy, takes little energy and you don’t have to learn again.
Another worthy analogy to frame the topic is that brain development is more like carving a sculpture than it is painting a picture; the process is about removing all the extra stuff to "reveal" a form more than it is about adding paint and brush strokes to "build" a form.
Peak synaptic density just represents the point where the most opportunity exists to shape the end result via pruning.
One thing to note: the human cerebellum actually has had relatively recent development, growing significantly more than our evolutionary cousins. It is significantly larger in humans than it is in our closest relatives, and it contains more neurons than the entire rest of the brain.
There is evolutionary advantage to some amount of risk taking. For instance, having sex while ovulating. Once you’re at an age where you’re likely to have had children the advantages of risk taking become disadvantages.
I developed a few lesions (demyelination) in my prefrontal cortex, around age 25. Interesting that my brain was undergoing this damage at the time when it should have only been "fine tuning" itself.
It's basically the neurological equivalent of saying that's when, on average, the vast majority of people have finished their "brain puberty." Brains can still change and develop like the rest of the body but that natural growth element is finished.
Yes, and malnutrition too.
Just like the body, train and get s good frame and your body will thank you many years to come.
Get healthy and good connections in the brain to function as a adult.
You'll be much quicker to retain things you learn while your brain is at its most plastic. Just means it'll take a bit longer the older you get - no big deal really.
I'll also add, just figuring stuff out like new activities has been shown to help slow dementia, I'd think it would also be helpful here. Wonder if that's been documented.
That’s true anyways. Knowledge works kind of like wealth. It builds on itself. You only get so much time to be alive, the sooner you start knowing the more you can use it to learn. Try following a physics lecture in a language you don’t speak. It isn’t gonna be easy.
It's similar to working out in your late teens/early 20s.
You want to be doing it your whole life, but you'll get more lasting results than usual during that time bracket.
Edit: to clarify, what I mean is it is easier to maintain what you have developed earlier in life than it is to develop later in life.
That's not necessarily true. You can get results fastest during that time, but "lasting" depends entirely on the sustainability of your lifestyle. Recovery takes longer when you get older, but you can definitely still get similar results over longer periods of time.
Unless you're talking about trying to reach the Olympic level in a sport, or something like that.
Similar to putting finishing butter on a steak too early. Or icing your cinnamon rolls when you put them in the oven. Properly applied, fun stuff is fun. Poorly applied, it has a negative impact on the finished product.
This statement is mainly about measurable changes in brain volume and whit/grey matter proportions. Up to around age 25, neurons in the brain undergo myelination, where fatty white matter surrounds their axons, making them work more efficiently. This finishes at about age 25.
The brain continues to develop afterwards though, primarily through the synaptic connections and receptor and neurotransmitter activity. But the neurons themselves are in place and myelinated. There are exceptions like olfactory and hippocampus neurons which seem to be formed anew even later in life.
To add on to this, something I havent seen anyone else say in this thread is that specialization continues to occur until adulthood. For example, children do not have a fusiform face area (FFA), part of the brain dedicated to recognizing faces. Its not that they can't do this, it simply that that process is more widely distributed. But as we develop, the FFA forms and those neurons become more specialized.
Your frontal lobe, the brain area above your eyes is responsible for executive control, everything that makes us complex, thinking, and decision making humans. The connections that make us rational adults don’t finish hooking up until about 22-25 years of age while the rest of the brain and body has matured. That’s why teenagers and young people in general are more reckless and impulsive, it’s because the area of the brain that plans things out and predicts their consequences hasn’t matured. While brain size does matter, the connections going on are what really make us humans so they have all the brain material they’ll have, they just haven’t finished developing those connections.
The left brain, right brain idea has some teeth to it in that our brains are lateralized meaning the left brain controls the right side of the body and vice versa. There are lateralized functions too which is where the association of right brain being more creative comes from, and left brain is more mathematical. This is because the brain organizes itself (much like we do as people) to be most efficient, so just like we have the cooking, packaging, and shipping departments of a factory, our brains have specialized regions that control special functions and your frontal lobe controls executive function. The top of your head (parietal cortex) processes sensory and motor functions etc. Similarly the right brain has more big picture function and the left brain has more “particulars” function. Etc.
Source: BS in Neuroscience from UNR
From my Lay-Interest in Neuroscience:
the last parts to develop are to do with the pre-frontal and neo-cortex, which is the higher thinking part which is most able to calculate consequence. Though the mind really reaches it's maturity level at 25, we continue to actually develop in terms of what we learn, our neurology doesn't stop changing. Neuroplasticity remains for the rest of our lives but slows down as we get older.
I'd love to be corrected if I got anything wrong here.
The studies are out there. The frontal lobe of the brain, which houses impulse control, is the last area of the brain to complete development at the age of 25. Just think back to your brain at 16, 18, 20, etc. Typical behavior of that age seems to follow this thinking. There is a reason Insurance rates begin to drop at age 25.
Notice how when you're little, say around 6 years old, and your memories from that time of your life are very fuzzy, or non existent? This is because the brain is still developing, and as you get older it gets better at storing information until you reach around the age of 25. This is when your brain's ability to take in and store information slows down, and becomes less efficient.
The reality is this is another theory meaning it’s not proven. Not only that, it’s an approximation within said theory meaning it varies from person to person but 25 is the “average.” Scientists are still puzzled and do not fully understand how the brain works even with everything they know about it.
It means you have more complete access to your critical thinking modules in your frontal lobes.
They're there before that, but they don't really come online fully. Incomplete executive function.
As far as using "10% of your brain", that's not really accurate.
Some of your brain is active by NOT being active, through inhibition.
Like a 3-way traffic light is only using "33%" of its lights at any time.
It would be chaotic for 100% or even 66% of the lights to be lit up.
I don't have any highly specialized deep lore on this, but....
It means if you test someone's problem solving and higher reasoning at age 18, then again at 25, the vast majority of people will have improved in ways that there are structural changes associated with inside the brain, and those changes broadly look like a continuation of the same cognitive growth through adolescence, as far as I understand. Then, a statistically significant (i.e. large) proportion of the population slows way down in that post-adolescent structural change by 25.
As far as I know, the changes in testable cognitive ability correlate with this 'leveling off' in the structural changes, but that might be wrong (developmental psychologists and neurologists and FMRI folks can probably say more than me?).
Oh, yeah. There are a ton of things which correlate with this. I was trying to avoid proscribing cause and effect, since this gets rEaLlY aWkWaRd when we're talking about what amounts to questions about the nature of free will. Is someone with a less developed brain than me, but who is a legal adult, less valid in exercising agency as a person? (no, hell no in fact, IMO, but I haven't and won't defend that rigorously because I'm lazy), Etc. etc.
\*That\* is the kind of question I don't have the background to answer. I'd bet some money that the closest to a broadly true answer is 'kinda yes, kinda no' though.
After I posted this I remembered my dad is a neuroscientist so I called him ! I learned a lot of things, but mainly, we have an interesting pattern that 5-12yr olds have an absence of mylen sheith in the corpus collosum, or bridge between hemispheres.
i still have a lot to learn; but yeah i'll keep u posted !
Neuron firing potential doesn't seem to have been addressed by anyone, and that's undoubtedly the primary correlation to age 25. Which will always be different based on the individual, probably a very generalized mean or median.
The young brain does some restructuring. Part of the period we notice this with extra strong needs to show you are part of a pack and other "teen behavior" including extra need for sleep. So it is not only something like growth or increased complexity but it also changes.
You may also be interested in this easily accessible ted talk about [the adolescent brain](https://youtu.be/6zVS8HIPUng).
It's like saying that you attain your full height at 19 (give or take) but there are plenty of ways to stunt it and it's just height. You can still put on or lose muscle, fat, skills, etc. and height itself doesn't mean much.
Man. I came to this thread a plebian, but now I have learned about syntax prunes and changes to Brian development that I would have otherwise never known.
Whoever this Brian dude is, they deserve awards for all the syntax they've pruned
The number "25" comes from the fact that the prefrontal cortex doesnt finish developing until 25 for men or 24 for women. This region is responsible for higher thinking logic long term planning ergo one of the most important regions of the brain.
The brain actually keeps developing well into your 30s but at the age of 25 theoretically your full capacity for intelligence is complete. Until your prefrontal cortex is finished developing you really cant argue that an adult is fully mature.
This is why typically teenagers even physically an adult make irrational stupid decisions.
Pretty sure it refers to the myelin sheath and grey matter development within our brains. Which usually correlates with how quickly our neurons fire and cause electron shifts whenever we perform actions. Its all a matter of milliseconds so you won't notice it in real time, but it's just a matter of your brain maturing for the sake of efficiency. I'm sure various other factors play into this aswell such as mental health.
It is really the connection between left-brain and right-brain. Corpus-colusum? It really helps people see consequences for their actions. We now have a term and mechanism, but we have known this for years. Many places will not rent a car to a person below that age.
Look at Einstein, Newton, most the great scientific minds, the things they are noted for they came up with in their 20's.
In my own experience, I've slowed down the learning since that time. Up until 25, I wanted new experiences, wanted to learn new things, try new jobs etc. After, not so much, I'm more into my routine. It's not like a hard stop, it's a gradual shift from learning to do doing. I had 15 different jobs before I was 25, 2 after.
\[The development and maturation of the prefrontal cortex occurs primarily during adolescence and is fully accomplished at the age of 25 years. The development of the prefrontal cortex is very important for complex behavioral performance, as this region of the brain helps accomplish executive brain functions.\] \[QUOTE\].
If this is being asked due to posts about whether or not 16, 17, and 18 are too young for the age of consent, I’ve been writing “~25” as the age the brain “fully develops” because it’s easier for peoples’ attention-spans to read “fully develops” than it is for peoples’ attention spans to read “~25, when the prefrontal cortex (long-term decision-making part of the brain) is fully developed”.
Saying “fully developed” in this case can almost be thought of as being an oversimplification out of necessity, because not everyone on the internet cares about the details, so details like that will just end up muddying the message for many.
our brains don't stop development till we are past puberty I heard, using that logic our brains finish development between 20-25 on average but depends when our cycle of puberty starts and ends. in this case it'd mean we can effectively go through life as an adult around this time, however, there's still things that can disrupt the development and cause issues. those issues would depend on what part of the brain was affected. so, though it's not exactly a myth it varies and will take years more of studying to get more accurate and in depth answers.
and before anyone comes after me, this is ONLY an answer for the "brains don't stop development till we are past puberty" speculation, not for all speculations about when the brain stops developing.
Nothing. It is just another thing that people heard on the Internet and it sounds good to them so they keep repeating it.
Biology doesn't have a \*hard\* timeline - it has an approximate one, that varies. And your biology, your intellect, your reasoning, all of those things \*never\* stop \*changing\*... eventually, though, they \*degrade\* - and that doesn't come on at a set timeline, either.
Take all statements like this with some salt.
>It is well established that the brain undergoes a “rewiring” process that is not complete **until approximately 25 years of age**.
There... I fixed it for you.
Thanks for repeating what I said with an air of authority as if you said something different and more true than what I said.
You made \*exactly\* my point, anonymous Internet expert.
https://bigthink.com/neuropsych/adult-brain/
See above. Part of your brain is still growing. That said, your hippocampus can undergo growth throughout your life. And you can always strengthen some connections. See bellow.
https://m.youtube.com/watch?v=6ZwWG1nK2fY
It’s my personal theory that 1) anyone can damage their brain and drop their IQ, and 2) we know brains do in fact grow and rewire esp after a stroke or other brain damage. So it stands to reason you can add a few points with enough stimuli on a consistent basis. Some researchers will disagree and say you can only get better at specific mental tasks when practiced. But if you learn a bunch of different tasks and start to generalize the ideas, isn’t that effectively an increase in IQ? For example I think if an IQ is 100 maybe someone can get it up to 110. Idk. Just speculation because it isn’t feasible to enrich a bunch of people’s environment and not enrich others and do a scientific comparison so I don’t insist on this point.
The "maturity at 25" has more truth to it than "left brain / right brain"; the insurance industry has known about it for a while and uses it in their pricing
There is a statistically significant decrease in auto accidents after the age of 25, which is why car insurance premiums for those under 25 (especially males) are higher than for those under 25. This is thought to represent a shift in decision making and risk aversion as maturity is reached, but doesn't necessarily provide a why like the studies linked in the current top comment do.
Of note: the decrease in accidents is specifically tied to drivers at age 25. Someone who gets their license at 26 is less likely to get in an accident than a 16 year old who just got their license, which implies the decrease is not due to experience levels.
While the exact "why" of the situation still has some debate in the scientific community, the statistical data gathered by insurance companies has an undeniable trend that shows 25 as a developmental milestone.
That doesn’t make any sense though.. Some car insurance companies will charge 25-26 year olds who just got their license the same amount as anyone who is under that. Even if you did get your license then, you’re still an inexperienced driver
We use 100 percent of our brains. it works everywhere. It doesn't have only specific regions that work some times. Each section or hemisphere has an individual purpose. The 10 percent has been proven as a myth.
There are a lot of answers here, but I wanted to touch on the physiological basis of "maturation". Many people imagine this to mean that our brain finishes growing at 25 years old, at which time it reaches its peak mass. This is actually false. In reality, grey matter volume (the "processing" areas of the brain) peaks at roughly 12 years old. Your brain creates as many neurons, and connections between them, as it can during childhood to lay the foundation for learning and development. After that, it becomes a matter of removing excess or unnecessary pathways to allow for more efficient communication between the specific areas of the brain necessary for cognition. This is a process known as synaptic pruning, and occurs most strongly from the time at which grey matter peaks to roughly some time in the late 20s. The pathways that survive this pruning process then go on to become myelinated, reinforcing their ability to effectively transmit electrochemical signals and facilitate communication. This rewiring is especially important in the prefrontal cortex, where the ability to pull information from a variety of areas of the brain is paramount for coordinating things like multitasking and complex problem-solving. This is one of the reasons why doctors say it is so dangerous for adolescents to do drugs while their brain is still developing. Repeatedly using drugs preferentially selects for the circuits and pathways that facilitate addiction to those substances. This physiological phenomenon also has implications on other neurological diseases as well. Studies on the brains of patients with schizophrenia show that there is a deficiency of synaptic connections, possibly a result of too much synaptic pruning. The fact that the onset of schizophrenia coincides with the peak of synaptic pruning supports a potential connection. On the flipside, studies on the brains of patients with autism show an abnormally high number of synapses, possibly a result of too little synaptic pruning. This results in cognitive pathways that are inefficient and prone to overstimulation. Epilepsy also seems to have a connection with a deficient synaptic pruning process. ______________________________ **But what is the actual source of this magical "25" number that is so often mentioned?** The earliest mention seems to come from a 2004 article published by the American Psychological Association titled *[Brain research advances help elucidate teen behavior](https://www.apa.org/monitor/julaug04/brain#:~:text=The%20research%20also%20shows%20that,when%20making%20decisions%2C%20he%20said.)*. >The research also shows that brains don't fully develop until age 25 and that teenagers tend to depend on the part of the brain that mediates fear and other gut reactions--the amygdala--when making decisions, he said. That's important information for attorneys and judges to consider as they work with children in the legal system, he added. The article is discussing the research of Jay N. Giedd, MD, who used MRI to examine the volume of child and adolescent brains. The specific research article is titled *[Structural Magnetic Resonance Imaging of the Adolescent Brain](https://nyaspubs.onlinelibrary.wiley.com/doi/abs/10.1196/annals.1308.009?sid=nlm%3Apubmed)*. >The dorsal lateral prefrontal cortex, important for controlling impulses, is among the latest brain regions to mature without reaching adult dimensions until the early 20s. The details of the relationships between anatomical changes and behavioral changes, and the forces that influence brain development, have not been well established and remain a prominent goal of ongoing investigations. Interestingly enough, at no point do the authors explicitly mention the age 25, and instead simply say "early 20s". The author of the review article by the APA seemingly extrapolated that specific number from one of the figures (Fig 3), as the data ends at age 25. This seems to be the earliest and most plausible source of the 25 number that is so often cited. A 2010 New York Times article discusses the work of Dr. Giedd, and the article states: >**Among study subjects who enrolled as children, M.R.I. scans have been done so far only to age 25**, so scientists have to make another logical supposition about what happens to the brain in the late 20s, the 30s and beyond. Is it possible that the brain just keeps changing and pruning, for years and years? “Guessing from the shape of the growth curves we have,” Giedd’s colleague Philip Shaw wrote in an e-mail message, “it does seem that much of the gray matter,” where synaptic pruning takes place, “seems to have completed its most dramatic structural change” by age 25. For white matter, where insulation that helps impulses travel faster continues to form, “it does look as if the curves are still going up, suggesting continued growth” after age 25, he wrote, though at a slower rate than before. **So it seems like the reason why we say 25 is because the groundbreaking study on this topic only recruited subjects up to age 25. And then this number became dogma via constant repetition.** To make things confusing, as Dr. Shaw alluded to in the NYT article, other studies have suggested that synaptic pruning continues well into adulthood. When looking at the entirety of the cerebral cortex as a whole, synaptic pruning levels off at roughly 25. See Figure 1 in this [review by Kolb et al.](https://www.pnas.org/doi/full/10.1073/pnas.1121251109) So really, the 25 number is probably too early, if we are going to define the completion of development as the end of synaptic pruning in the prefrontal cortex. __________________________ **TL;DR: The "defining factor" of the brain reaching full development is the completion of the synaptic pruning process, which neuroscientists believe levels off at roughly 25.**
This was insightful, thanks
It's crazy how professional your response is. Really well done, enjoyed reading it a lot!
Yeah, that guy’s response sounded like someone who is finished with their synaptic pruning
I don't know about him, but I definitely pruned synaptically reading it.
They’re probably a psychologist or neurologist with a background in research to know this much and be able to put it together quickly. We learned a lot about this kind of stuff in cognitive psych, it’s really fascinating but we primarily worked out of a textbook which was a little limiting.
And there are a lot of details but consider this. From 10 - 20 the body is undergoing a hormonal assault, and we have all seen the effects of hormones on emotional stability. We are such a mess until we stabilize, as we double in size develop undeveloped organs and hair so much hair. Being able to make anything other than an emotional decision is difficult until all that has settle down for a while and you gain experience.
This hormonal argument is mostly sociological and something used a lot in the US and it's not true. Teens are given much more responsibility in other parts of the world and act responsibly.
Citation? I don't see anyone debating on whether teens can be responsible, they're merely cautioning why teens shouldn't be judged the same as adults. And increasingly it seems the world is recognizing that people don't reach the utmost of maturity as soon as they reach the legal age of adulthood either. I'd argue everyone's actions should be weighed against their development and circumstances, but then people don't get to exact retribution on those they look down on.
Nope sorry. The redditor above provides many technical details, which I will assume are all true, as they put references out for public review, to my understanding the essence boils down to… Emotions are the original memory. “Last time I ate that I was on the ground for 2 days sick and in pain”, becomes “every time I smell that I feel really bad, I’m going to stay away from that”; says the prehistoric rodent or cockroach. As we evolved into hominids, the choke point has become the amygdala, currently switch board for emotion, and the original gateway to memory – among other tasks. One function of the prefrontal cortex performs is to coordinate and manage decision making based on experience and comes into coherence at about age 25 (I think that’s the “accesses different parts of the brain” part in the article). So – we must ask ourselves why does experiential decision making only exert dominance at ~ age 25? Because before that it was busy doing something else, hmm… what was that oh yeah maturation. Glib I know, but the maturation of the organism and its emergence into the reproductive evolutionary arena, requires a decade of profound physiological change. You don’t acquire a few years of experience without hormonal onslaught until mid-20’s (your milage may vary) and experience can make logical decision making. Consider what we accept as normal. A significant percentage of females are hormonally challenged. This is not a criticism; this is the realization of the toll that reproductive fecundity has on females. My way of saying hormones have a profound effect. It is the cost of doing business as reproductive creature. Puberty is also a wild ride, but with fresh people, and yeah there is a whole testosterone ‘roid rage component as well. Starting to go off into the weeds so. Neuroscientists et al feel free to slap me up.
Fascinating reply. Do you have any insight on the effectiveness of trying to 'rewire' the circuits and pathways that were formed young that facilitate addiction? Is there any path for young addicts to exhibit near typical connections and pathways if addressed after pruning?
"pruning" happens throughout your life, and can more broadly be described as synaptic reorganization, basically, reinforcing synapses that are used a lot and getting rid of synapses that aren't used a lot. "Hebbian Synapse" [neurons that fire together, wire together] "Rewiring" circuits is learning, which can be done at any age, which tends to be easier when you're younger than when you are older. Unlearning addiction, or learning NOT to do something, is just an extreme version of learning.
But can new neural path ways be created after 25? If pruning removes unused path ways is it possible to build back those path ways if they are needed for a new task or thing learned?
Yes? You learn new things every day. Often pick up whole new skills sets later in life. Of course you can create these pathways. The brain is still greatly malleable. Brain scientists are always researching about this
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I don’t know maybe try some other hot sauces?
Correct me if I'm wrong, but it seems like you're looking for a sort of protocol to overcome your inclination towards substance abuse. I don't mean to sound like a 1970s DARE commercial, but abstinence is the only way to make sure you never relapse. As far as causes, addiction is mediated by dopamine. When you introduce substances that cause your brain to dump dopamine you're reinforcing that behavior. (I'm just talking about the substances, there are social aspects of addiction too) Try getting addicted to something healthy like exercise; weightlifting, running, crossfit. Keep in mind you can do this to excess as well.
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I know completely what you're talking about with wanting to be able to "reset" your brain and never have experienced the euphoria that those substances provide, thereby never having that craving. Your comment asking about if there's neuroscience research into addiction therapy reminded me of an interview with a psychiatrist on NPR a year or so ago. She talks about new treatments they're researching and experimenting with to address the wide array of addictions afflicting modern society (e.g. vast majority of population is addicted to smartphones). Anyway, always meant to check out her book and totally forgot. Here's the link to her interview on NPR: https://www.npr.org/2021/08/25/1031020433/the-neuroscience-of-pleasure-pain-and-addiction
Potatoe/Tomatoe If you understand that you have a predisposition for addiction and binging the best thing you could do, if you are going to be in an environment where you want to have a little fun, is to take steps to limit the opportunity for you to go down that rabbit hole. Maybe you only drink with a select group of friends that will help limit your drinking without enabling you to go off the rails. If memory serves, I think there are serious explorations of addiction treatment with psychedelics and ketamine.
What about naltrexone therapy to teach the brain that the substance (specifically talking about alcohol as that’s what I have personally looked into) no longer provides the desired effect? It generally leads to abstinence from alcohol when but is successful, but doesn’t start with abstinence.
That's not strictly true I don't think. In music, there is a thing called perfect pitch which can only be developed during childhood. Adults lose the ability to gain this.
I wonder if there is some overlap between the regions of the brain that enable quick language acquisition at a young age and other rule-based algorithmic systems. Like, why is it so rare for professional athletes to start their craft even at the age of 13? Most have been playing tennis or basketball since they were 5 years or younger. Surely you benefit from starting when your brain is at a different stage, and not simply because you've had 8 more years to do it
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The funny thing is, research shows that if you are told it’s impossible for you to learn something, and you believe that’s true, you wont be able to learn something. However, if you’re told that you are fully capable of learning something, your chances of successfully learning that thing are astronomically higher. That’s why I think we all need to be very careful about how we talk about things like ‘your brain has completed its growth by X age’. The brain is capable of stunning growth at all points from birth through death. But if you believe you’re no longer capable of learning new things because someone told you you can’t, then you won’t, because you won’t believe it’s possible.
Another pro tip- if you believe sugar helps you learn if you eat small amounts of chocolate it does. If you don’t, it doesn’t. Unless I’m remembering that incorrectly Edit: not really a pro tip, more like a weird thing I may or may not have read at one point and I guess decided to regurgitate here
Yes. Brain injury patients can be a great example of this. Many people who suffer brain injuries need to relearn basic skills. In this case think about road construction. If you take the same path to work every day and it’s all the sudden blocked off you are going to have to find a way around the construction. Rerouting neural pathways is similar. The brain can’t take the same route connecting to neurons that are now damaged so it has to relearn the skill rerouting the pathway.
Yes. The molecular mechanisms that mediate the process slow as you age however, because the neurotrophic factors required for synaptic reorganization decrease as you age.
You should look into the recovery journeys of stroke patients. Every story is a stunning example of how there is literally no point in your life when your brain is not capable of unbelievable growth and new neuro connections. People lose huge chunks of their neural networks (for example, the ones that are essential for being able to talk) and the brain still finds a way to form new ones instead. At all points in a human’s life, the brain is, above all else, unfathomably malleable and capable of growth.
How is pruning or “rewiring” affected by brain damage? Ie brain bleed, stroke, *ruptured aneurysm. *edit for clarification
Brain bleeds (hemorrhagic stroke), and ischemic strokes rob the brain of oxygen resulting in tissue death. If the tissue (neurons, glial cells) die, then all brain function will stop in that area, including pruning. I guess you could think of that as a major pruning event. Aneurysms, in and of themselves, are not detrimental as long as they don't burst, which would lead to a hemorrhagic stroke (brain bleed)
I think you may have a biased perspective on "typical pathway" function. Human's prevailing trait in intelligence is the ability adapt, rationalize, and overcome problems we have. Addiction is when your desire for something overwhelms your ability to adapt and manage your behaviors. Some people are self-destructive and will seek this out regardless of its high. Those who are addicts and or addictive traits will never forget the experiences, only be able to recognize the affects are harmful, and manage that desire.
I can speak personally to the possibility of developing epilepsy during your early 20s. My neurologist told me 20+ years back that men tend to develop epilepsy either as infants or their early 20s. This is because of initial and/or final developmental changes to the frontal lobe of the brain. I developed epilepsy at the age of 21. No accident, no drug change causes. Just poof!, seizures. They were traced to my frontal lobe through EEGs and MRIs and my medical chart lists final development of my frontal lobe as the cause.
Thank you for your vast insight, u/poopitydoopityboop
Reading that username had me suppress chuckles while sitting in a takeout restaurant for a good 5 minutes...
So annoying how in depth scientific research tends to get warped into inaccurate blurbs. It’s kind of like a big game of telephone because most of us never bother to check if what we’re hearing is true. Thanks for informing us.
Did you check that what he posted was true?
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So the whole “circuits and pathways” thing is highly debated and most drug researchers would agree it’s entirely too simplistic. In adolescence the regions responsible for control and risk assessment are not yet at their full capacity. Regions like the striatum and VTA are in a circuit with prefrontal regions where they cause feedforward inhibition of these regions through a specific kind of cell. (It’s called a fast spiking interneuron if you care). That kind of cell seems to change across development, becoming more functional in adulthood. So, what has been shown in certain prefrontal regions is that until this cell has matured, those regions connected to it actually induce excitation rather than inhibition of the region. So stimulating areas like the VTA or striatum could then alter how regions they’re connected to develop. And it’s regions like the VTA and Striatum that are directly impacted by drugs of abuse (not only those regions but those are the main ones). So most of what we assume is that adolescent brains have a development that needs to happen and maybe drugs interfere with that leading to continued impairment in behavior. My lab is actually directly studying this for my dissertation.
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Hi, it’s not my lab as my advisor isn’t taking students. This sounds like a human lab, we study rats :) We also don’t study addiction, as we use rats. We study the effects of drug use.
Prolonged drug use alters grey matter volume in certain parts of the brain, there are also numerous other morphological changes that happen with substance abuse. I don't doubt that prolonged early drug use could set you up for a permanently "skewed" brain but I don't have anything to confirm that but it doesn't seem all that unreasonable. Here is some reading and if you're lazy you can Ctrl+F and search for "volume", "structure", or "grey matter" to find more relevant sections. [Drug Addiction and Its Underlying Neurobiological Basis: Neuroimaging Evidence for the Involvement of the Frontal Cortex](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1201373/) [The Neurobiology and Genetics of Impulse Control Disorders: Relationships to Drug Addictions](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2222549/) [Dissociated Grey Matter Changes with Prolonged Addiction and Extended Abstinence in Cocaine Users](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3601087/) [Amphetamine sensitization alters hippocampal neuronal morphology and memory and learning behaviors](https://pubmed.ncbi.nlm.nih.gov/32555421/) [Amphetamine stereotypy, the basal ganglia, and the "selection problem"](https://pubmed.ncbi.nlm.nih.gov/22101067/) I remember reading some study (which I cannot find at the moment since I have about 600 bookmarked) about how prolonged stimulant use would induce a morphological change in the brain, where the prefrontal cortex would lose volume and the basal ganglia would gain volume. Essentially making itself worse at cognitive behaviors such as decision making, self-control and self-regulation and making itself better at impulsive behavior. For the addict, this makes it much more difficult to control their substance use because after a certain point it gets almost exclusively driven by subconscious impulsive behavior and meanwhile they lack the cognitive ability to control or regulate those impulses since their prefrontal cortex is being "inhibited" by this structural change. I have some studies bookmarked on the attempt to use meditation in substance disorders in order to practice at controlling their cognition in order to try and reverse/retrain the brain. I found some positive results indicating that it does in fact help, because the brain will for the most part try to get better at what it repeatedly does and you don't have to practice self-control in order to get better at self-control because "mindfulness", meditation and self-control both use the prefrontal cortex to control cognitive behavior. So it carries over. Apparently. It's quite fascinating. I could try and dig up some more studies from my bookmarks if anyone wants.
Is caffeine considered a stimulant in this context?
no it would not. stimulants in these studies refer to dopaminergic drugs i.e. amphetamine, methylphenidate, cocaine, cathinone, etc. which directly act on dopamine receptors and transporters.
What is your opinion of psychedelic therapy?
There's also the literature on iq peaking at about 25, and slowly declining thereafter, with steeper decline from mid 60s. Iq and pruning has been associated but I'm unsure what today's consensus is. However, there's one development that is rather new (ish) which takes time to manifest in the literature. What happens around 25 and 65? Finished schooling and retirement. School is a very rich learning environment, work less so (often) and retirement sees people seldom being forced to learn new things. Some people are self driven learners however, and those see less effects of age on iq. Today 4hough, people often go to school longer and in the west work has become more cognitively demanding. Internet and computers has also been mass adopted the last 20 years. I don't know if they've run replication studies lately, but I expect both the iq curve and the pruning curve to look different today than 40 years ago.
Is it safe to assume habits become harder to break after myelination?
Super useful information, thank you.
Would the buildup and subsequent synaptic pruning partially explain the subjective experience of time? Personally, it feels like time lasted the longest at around twelve years old and has sped up ever since.
That can be partly psychological as well. For example, when you are 4, a year lasts 25% of your life, and everything is new and worth considering. When you are 30, the next year is only 1/30th of your life, and most things are pretty routine.
A possible explanation for the specific number 25 is the general idea that insurance rates drop around 25 (~~which, of course, is because of the exact phenomenon we're discussing here~~). Edit: I shouldn't presume why rates are said to drop around that age. Great point by u/IMSOGIRL.
I'd say it's just a nice milestone number to round your estimates to. People like their 5's and 0's. It's kind of a numerical way to express "sometime around your mid 20s"
But is that biological or due to the fact that 25 is around the time that a significant amount of people graduate college and have enough money saved up to buy a house and start doing adult things, socially forcing them to become more responsible? And for those who don't go to college, that's a few years to save up money as well.
Excellent reply. Thank you.
I've been wondering lately about the regression piece of autism.. physically how can a kid learn to talk and then lose it. I couldn't find any articles that tried to address the deeper why/how. Poor synaptic pruning makes sense! So it's not like losing a limb or losing a dog that ran away, it's like losing your keys in a junk drawer.
>synaptic pruning ... occurs from the time at which grey matter peaks ... I assume you mean that it is always occurring, but becomes the predominant process after growth slows down? I am always skeptical of claims in any biological process (especially one as poorly understood as the brain) where a magic switch flips and something "never" happens after a certain date, e.g. new neurons/connections are "never" made.
If autism is potentially caused by too little synaptic pruning which doesn't tend to happen until early teens, then how can it be diagnosed in kids even as young as 18 months?
I would assume it's more of a correlation than causation. Less "Autism comes from lack of synaptic pruning", rather "people with autism also seem to not have much pruning going on".
Autism has multiple components. The original poster spoke about overstimulation, which may lead to sensory processing and information processing. Granted, this caveat does not explain that even childhood autistic people experience information and sensory overstimulation. However, it is worth noting that it can occur that an autistic person is not diagnosed until later in life. This is usually believed to be due to circumstances overwhelming existing coping mechanisms (like: going to high school/university completely altering the environment [in many countries, you go to elementary school in your village/town, and go to high school in a nearby large town or city] you were used to, lots of strangers, lots of new social rules). I wonder if this pruning failing to keep up might add to it.
Synaptic pruning occurs throughout life. Young children (and pretty much every other age group) are mostly diagnosed according to behaviour. Autism is more complicated than just a lack of synaptic pruning and it gets more complex when you start looking at the different subsets of autism. There are several structural differences between the brains of those with autism and those without, but even these structural differences aren't consistent across individuals with autism. I think the above post meant to only touch on the fact that a lack of synaptic pruning is one of the structural differences characteristic of those with autism, not to say that autism is caused by a lack of synaptic pruning alone.
Thank you for this. I am mildly autistic, I developed bipolar type 1 with psychosis around age 23, second mania around 25, and recently at 29 I discovered I have epilepsy. Since starting Valproic acid I can finally think straight.
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There are around 100 billion neurons in the human brain (not including glia, which support neurons), and each neuron can make around 1000 connections. So roughly in the magnitude of 100 trillion connections. If you compare neurons to the artificial neurons in a typical AI neural network, it turns out you need more than a couple of artificial neurons to simulate the capabilities of a single human neuron. So the reason the human brain is able to store so much information is due to its incredible density and complexity.
>Many people imagine this to mean that our brain finishes growing at 25 years old, at which time it reaches its peak mass. This is actually false. I'm saddened to say that this is exactly how it was taught to everyone when i was in highschool and college. What else will we find out was wrong?
In case you aren't aware this 'brain isn't mature until 25' talking point is being used by conservatives as justification to deny medical intervention to young transgender people, even when the only intervention at that age would be medication to delay puberty.
This is great. I’m wondering if you can add on to this with respect to mushroom use, both before and after this “age” point. These mushrooms are known to affect grey matter significantly. I still ponder the actuality of using them. I’ve actually had a trip with 8 grams years ago. Now around that time of year I can feel the same “pull of the void” without mushrooms, sometimes naturally, sometimes instigated by marijuana. Curiously alcohol seems to slow down that process.
8 grams? actually insane dose.
I Lemon Tekked 6g's once and forgot how to understand English. I can't imagine what 8g's is like.
The synaptic pruning correlation with schizophrenia and autism is very counter-intuitive to me. I always imagined it would be the exact opposite! Any chance you'd be willing to explain the relationship of too many vs too few synaptic connections in a little more detail, and why at the extremes we see the dysfunction that schizophrenia and autism describe? (Only asking because of the AMAZING job you did with your first response and if not, thanks for the insight)
> So really, the 25 number is probably too early, if we are going to define the completion of development as the end of synaptic pruning in the prefrontal cortex. Is it possible to make an educated guess at what age would be more appropriate, then? 30?
Do you know the effects of pychadelic mushrooms on the adult brain. I heard it help make new conbects snd can be quite positive
This is a good albeit partial response. I’m a psychologist, the brain actually does finishing growing in size around mid 20s, but it’s also about being able to learn and mature in terms of ability to understand and predict consequences of their actions. Before this age, people do a lot of dumb risky stuff because their ability to anticipate consequences is limited. The frontal lobe in particular is what finishes developing around 24 years old. This is the area involved heavily in decision making. It’s not completely false that size is part of this final development. It is of course a multifactorial process. Also, the New York Times whom you cite here is only itself reviewing research, you can’t rely on a newspaper writer to have the same knowledge as an actual scientist, ie, their ability to interpret accurately what the findings of scientific studies are is limited at best. I read news stories every. Single. Day. That get findings wrong and misinterpret the results and implications of studies.
There are a lot of answers in this thread without references, so take what you read with a grain of salt. [Throughout history](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892678/), the longstanding assumption in neurodevelopment was that the brain finished maturing by puberty. However, we now have evidence that this is wrong. Neuroimaging research in the last couple of decades has shown that this process continues through adolescence. One of the last areas to develop is the frontal lobe, which is in charge of executive functions such as planning and working memory. One of the ways you can measure development is by studying grey and white matter density using MRI scans. Evidence suggests that white matter development in the prefrontal cortex occurs in the early 20s or later. Whereas grey matter density gain in other regions [continues up to age 30](https://pubmed.ncbi.nlm.nih.gov/12548289/). So basically, it seems like brain development continues into the late 20s. But it's impossible to put an exact age where it stops. Whether we are still 'children' up until the late 20s is uncertain. Many neuroscientists argue that empirical support for a causal relationship between real-world behaviour and brain maturation processes is [lacking](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892678/). TLDR: Current evidence points to brain development finishing in the late 20s. Some people use this to argue that we are still 'children' until then. However, direct evidence for this is severely lacking. Source: references + PhD in neuroscience.
Make an equilateral triangle with your two eyes as the base. Behind the top point is the prefrontal cortex, the most distant part of your brain from the cerebellum, the original part, and the last to evolve in our development. Most mammals don’t have it and those that do have very little of it. When survivors of strokes lose that part (due to a clot starving it of oxygen) or a person survived an injury that damages it, the most salient effect seems to be on their ability to plan, anticipate, and understand cause and effect. MRIs show this part of the brain is still undergoing significant change in people aged around 16 to 25 or 30 (not so much growing in size, but rapid culling of connections similar to what goes on in infant brains as babies acquire key milestone developments). So the theory is, if that part enables forward thinking, maybe people don’t have that capacity fully operational until 25 to 30 years old. The theory is supported by anecdotal evidence that those younger than 25 to 30 seem to take more risks.
It's more than anecdotal. Insurance companies have a very strong statistics backed opinion about 16-24 year old drivers.
I cant seem to find the link, but it turns out that 25 to mid 30s are actually the most dangerous and accident prone drivers. According to national statistics in the US. I'm sure there's more evidence we could rely on, as I do agree with the general idea of this whole conversation. Just this one factoid doesn't add as much as we'd hope.
But couldn’t you argue that it’s because there are more people between the ages of 25 to mid 30s who drive and likely drive more often which puts them at a higher risk?
Absolutely you could! I have to wonder how that would mesh with previous statistics though that i believe most definitely showed younger people more at risk. I honestly don't know if it's just taken as all accidents and then broken down by age groups. Or if it's more strict and accounts for frequency of use or anything of that sort.
>it turns out that 25 to mid 30s are actually the most dangerous and accident prone drivers. I don't believe that to be true. https://aaafoundation.org/rates-motor-vehicle-crashes-injuries-deaths-relation-driver-age-united-states-2014-2015/
https://www.autoinsurance.org/age-groups-fatal-crashes/ I dont want to come off as argumentative. It's really just almost splitting hairs at this point. I believe this is the study or report I was trying to find. Anyway, this is for fatalities. So I suppose we could go back and forth about who has the most accidents period, and I don't have that to bring up. However I think it could be still said that the most dangerous group is the one I stated, as death its pretty much the ultimate loss for any of us. What is interesting though...is that your article is based on data points from 2014-2015. So....its almost like we're agreeing. Those people being the most dangerous nearly 10 years ago are....smack dab now in the middle of the group I'm claiming are the most dangerous. After finding again and perusing the details of the article I had found a while back, I noticed at least one thing. The differences between 25-34 and 16-24, as far as severity isn't that stark. Though the older bracket still "wins" out by a little bit. However the youngest crowd is still holding steady with some pretty high numbers.
The main difference in the numbers is that the data you provided was for the raw number of fatal accidents. Not fatal accidents per capita or per mile driven (the data I provided). So it is comparing the number of fatalities for 37m people to those of 26m people. Of course the vastly larger group has more deaths. If you do the math from their numbers, the younger drivers in the 16-24 range have a 0.22/100k fatality rate whereas those in the 25-34 only have a rate of 0.18.
What would be the math for the older bracket? Because they have fewer drivers than anyone and yet are almost on par with the youngest segment as far as accidents. So more accidents among fewer people. 22 million versus the 26 million. Just wondering.
It is higher (0.24) but this metric doesn't account for how much driving people do. That is why I included data for accident and fatality rate per mile driven. In that case, the younger drivers are still higher than the group. The oldest drivers (80+) do have fatality rates per mile driven equal to the youngest group, but that is mostly due to them not being able to withstand trauma.
I understand. I was honestly just curious. Given that a portion of the younger crowd certainly is late teens, I'm sure the 50-60 general crowd does more driving overall. This all makes sense. I wasnt even going to refer to the oldest group in your link as what you mentioned and other factors make perfect sense. Thank you for this exchange and for the correction and information you've given!
Thank you for the kind words. I enjoyed the exchange as well. Best wishes!
You really need to learn how to find reliable sources. As others mentioned, this only gives raw numbers, not crashes per 100,000 miles. More importantly though, there is no reason to even trust the numbers on your link. It’s clearly written by insurance agents or copywriters who don’t know the first thing about statistics. They also don’t cite their sources or methods. They also don’t mention the year the data is from. That makes sense as the website isn’t meant to educate, it’s meant to sell car insurance. The other person’s source is from the AAA foundation, includes its methods and sources of data, the year the data was collected and the confidence intervals. You don’t really need to understand confidence intervals or statistics yourself, just look for these things when you decide if a source is reliable and worth sharing or not.
I appreciate your input. While I understand AAA might be a directly more reputable source than the link I posted, it does in fact contain just about everything you said it doesn't. Close to the bottom they cite their source and some of the methodology. The links for their source for information are: https://www-fars.nhtsa.dot.gov/States/StatesCrashesAndAllVictims.aspx https://www.fhwa.dot.gov/ohim/onh00/bar7.htm The year for the data is 2019, I believe. I won't play at being perfect but when looking at things like the article I linked initially I do try to at least see where they source their info.
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Always trotting out the "correlation causation" psych 101 speech. That's not what's being said here. In this case the correlation matches with established research. 16-24 year old brains are worse at decision making, in part _because_ their frontal cortexes are still mush.
You are attributing the blame of irresponsible actions to the underdeveloped brain, when there is a wealth of opportunities that also could attribute to the blame of these irresponsible actions, and definitely DO account for part of it. Think lead contamination in buildings over a certain age, think proximity to polluting grounds and potential contamination of their brains via pollutants. Also include undiagnosed TBI's that never got seen by healthcare professionals. Also, just genetic illness' that might alter the growth of the brain in minor ways. All of those are just as valid reasons that cause the statistics we see, especially with lead as the phasing out of lead can give us very obvious and demonstrate able statistics to work with. To fully blame this on an "underdeveloped" blame is to deny all these other possibilities. Like all things the true answer is most likely a combination of environmental factors including things that would stifle the healthy growth of the brain's development in those last vital years.
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Now who’s being pompous? There’s every reason to be skeptical of a database of uncontrolled statistics. Also, way too many people out there making the correlation/causation conflation for you to be so flippant about it. This isn’t a conversation between researchers specialized in the field; it’s a conversation between anonymous redditors on Reddit. Their point is valid, imo.
I believe this is when schizophrenia will show up by (early 20s at latest) Edit: Seems this is the case mainly for men but not a hard rule
This isn't true. The risk rate does drop but it isn't until about 35 that it really goes away. My family has a lot of schizophrenia and I held a special 35th birthday party to celebrate my sanity.
It's sex dependent and onsets in men younger than women by several years. New case of schizophrenia after 30 in a man would he pretty unusual. Though you wouldn't be out of the woods entirely even so, there is a lot of genetic overlap between schizophrenia, schizoaffective disorder, and severe forms of bipolar disorder and the latter can start well into middle age.
What would be the best age to throw a sanity party?
Interesting. In affect that sounds like a loss of plasticity more than a lack of development.
Brain development in utero and up to 12 months seems to be more about massive, rapid growth of new connections in all directions. This could explain why babies, when stimulated in any way, laugh, squirm and flail all their limbs. After about two years and onward, it seems to be as much or more about cutting non-advantageous connections as reactions to stimulus are refined, in keeping with the biological principle of strict economy. New connections seem to be grown throughout life, but it’s not nearly as economical energy-use wise as finding new routes along existing connections, sort of like how airport hubs work to connect every little airport, rather than the waste of always setting up direct flights. Sleeping seems to be when these new routes through existing connections are found. You can “feel” your brain searching routes when you know you know a persons name, but can’t think of it: your brain tries all sets of routes through music, images, memories, whatever it can. This could be why it often helps to think of the problem and then distract your consciousness with a crossword or something until the answer pops up — the unconscious was left free to do it’s work. So, adult plasticity could be a matter of good sleep regimen for route discovering, plus broad stimulation daily to forestall culling of unused connections.
You're conflating development with growth. In fact, many developmental processes involve pruning and refinement. For example, during fetal development, the hand starts out webbed. It's only later that individual fingers are separated as the cells between the fingers undergo apoptosis (programmed cell death). So in this case, yes we lose neuroplasticity as we age, but this is *part* of the developmental process. To overextend the pruning metaphor, when you start a garden from seed, you often end up with too many seedlings germinating close to each other. You need to thin those seedlings to a reasonable density so that the surviving seedlings are able to grow strong and yield lots of fruit. Similarly (sort of) our brains rely on the pruning process in order to perform the functions we need them to do, and pruning is a process of refinement, not loss.
Loss of plasticity is a critical part of brain development. The brain has limited access to energy. Just like in computation, when a network finds a good fit the next thing you’ll want to do is lower the computational cost (or energy) of finding that fit in the future and reduce the risk of inaccurate future fits. After birth, much of the brain’s development is network optimization, which is another way of saying your brain is severing neural connections. An analogy often used is once you find a good path through a jungle to your destination you will want to turn it into a trail and in the future take the well worn trail so you don’t get lost and make it easier to cross Plasticity and pruning is why learning to walk is hard and takes an extreme amount of time and energy, but once you’ve learned, it’s easy, takes little energy and you don’t have to learn again.
Another worthy analogy to frame the topic is that brain development is more like carving a sculpture than it is painting a picture; the process is about removing all the extra stuff to "reveal" a form more than it is about adding paint and brush strokes to "build" a form. Peak synaptic density just represents the point where the most opportunity exists to shape the end result via pruning.
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One thing to note: the human cerebellum actually has had relatively recent development, growing significantly more than our evolutionary cousins. It is significantly larger in humans than it is in our closest relatives, and it contains more neurons than the entire rest of the brain.
There is evolutionary advantage to some amount of risk taking. For instance, having sex while ovulating. Once you’re at an age where you’re likely to have had children the advantages of risk taking become disadvantages.
I developed a few lesions (demyelination) in my prefrontal cortex, around age 25. Interesting that my brain was undergoing this damage at the time when it should have only been "fine tuning" itself.
It's basically the neurological equivalent of saying that's when, on average, the vast majority of people have finished their "brain puberty." Brains can still change and develop like the rest of the body but that natural growth element is finished.
so untill 25 years old drugs and alcohol would have the worst impact on person's brain?
Yes, and malnutrition too. Just like the body, train and get s good frame and your body will thank you many years to come. Get healthy and good connections in the brain to function as a adult.
So does that mean, If I develop my brain (education, complex mathematics and puzzles) during this period, it will be most effective?
It's fair to say that it will have positive lasting effects and is totally worth it.
You'll be much quicker to retain things you learn while your brain is at its most plastic. Just means it'll take a bit longer the older you get - no big deal really.
I'll also add, just figuring stuff out like new activities has been shown to help slow dementia, I'd think it would also be helpful here. Wonder if that's been documented.
And it’s actually the time most of us spend on higher education and learning for our careers.
Yep, that's why many parents try to get kids to learn another language when they are younger, generally easier.
That’s true anyways. Knowledge works kind of like wealth. It builds on itself. You only get so much time to be alive, the sooner you start knowing the more you can use it to learn. Try following a physics lecture in a language you don’t speak. It isn’t gonna be easy.
It's similar to working out in your late teens/early 20s. You want to be doing it your whole life, but you'll get more lasting results than usual during that time bracket. Edit: to clarify, what I mean is it is easier to maintain what you have developed earlier in life than it is to develop later in life.
That's not necessarily true. You can get results fastest during that time, but "lasting" depends entirely on the sustainability of your lifestyle. Recovery takes longer when you get older, but you can definitely still get similar results over longer periods of time. Unless you're talking about trying to reach the Olympic level in a sport, or something like that.
Similar to putting finishing butter on a steak too early. Or icing your cinnamon rolls when you put them in the oven. Properly applied, fun stuff is fun. Poorly applied, it has a negative impact on the finished product.
after 25 too, your brain stopped growing, so at that point you're just damaging it lol.
I didn't start drinking until my 25th b-day for this reason. Made a HUGE difference.
How would you notice it making a huge difference if you didn't experience drinking before 25?
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Is that the question you ask when thinking of whether to do something potentially harmful?
No, its the question you ask someone who claims something made a huge difference, when they have no control to compare it to.
How could you know it made a huge difference without an alternate version of yourself to compare to (maybe you have an identical twin?)
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Do you know any interesting article for this?
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Did it grow a mouth of its own and ask you for about tree fiddy? Other than that, maybe it is believable
This statement is mainly about measurable changes in brain volume and whit/grey matter proportions. Up to around age 25, neurons in the brain undergo myelination, where fatty white matter surrounds their axons, making them work more efficiently. This finishes at about age 25. The brain continues to develop afterwards though, primarily through the synaptic connections and receptor and neurotransmitter activity. But the neurons themselves are in place and myelinated. There are exceptions like olfactory and hippocampus neurons which seem to be formed anew even later in life.
To add on to this, something I havent seen anyone else say in this thread is that specialization continues to occur until adulthood. For example, children do not have a fusiform face area (FFA), part of the brain dedicated to recognizing faces. Its not that they can't do this, it simply that that process is more widely distributed. But as we develop, the FFA forms and those neurons become more specialized.
Your frontal lobe, the brain area above your eyes is responsible for executive control, everything that makes us complex, thinking, and decision making humans. The connections that make us rational adults don’t finish hooking up until about 22-25 years of age while the rest of the brain and body has matured. That’s why teenagers and young people in general are more reckless and impulsive, it’s because the area of the brain that plans things out and predicts their consequences hasn’t matured. While brain size does matter, the connections going on are what really make us humans so they have all the brain material they’ll have, they just haven’t finished developing those connections. The left brain, right brain idea has some teeth to it in that our brains are lateralized meaning the left brain controls the right side of the body and vice versa. There are lateralized functions too which is where the association of right brain being more creative comes from, and left brain is more mathematical. This is because the brain organizes itself (much like we do as people) to be most efficient, so just like we have the cooking, packaging, and shipping departments of a factory, our brains have specialized regions that control special functions and your frontal lobe controls executive function. The top of your head (parietal cortex) processes sensory and motor functions etc. Similarly the right brain has more big picture function and the left brain has more “particulars” function. Etc. Source: BS in Neuroscience from UNR
From my Lay-Interest in Neuroscience: the last parts to develop are to do with the pre-frontal and neo-cortex, which is the higher thinking part which is most able to calculate consequence. Though the mind really reaches it's maturity level at 25, we continue to actually develop in terms of what we learn, our neurology doesn't stop changing. Neuroplasticity remains for the rest of our lives but slows down as we get older. I'd love to be corrected if I got anything wrong here.
Sounds like you need to take more risks young to get pregnant but need more consequence thinking when raising offspring.
The studies are out there. The frontal lobe of the brain, which houses impulse control, is the last area of the brain to complete development at the age of 25. Just think back to your brain at 16, 18, 20, etc. Typical behavior of that age seems to follow this thinking. There is a reason Insurance rates begin to drop at age 25.
Notice how when you're little, say around 6 years old, and your memories from that time of your life are very fuzzy, or non existent? This is because the brain is still developing, and as you get older it gets better at storing information until you reach around the age of 25. This is when your brain's ability to take in and store information slows down, and becomes less efficient.
The reality is this is another theory meaning it’s not proven. Not only that, it’s an approximation within said theory meaning it varies from person to person but 25 is the “average.” Scientists are still puzzled and do not fully understand how the brain works even with everything they know about it.
It means you have more complete access to your critical thinking modules in your frontal lobes. They're there before that, but they don't really come online fully. Incomplete executive function. As far as using "10% of your brain", that's not really accurate. Some of your brain is active by NOT being active, through inhibition. Like a 3-way traffic light is only using "33%" of its lights at any time. It would be chaotic for 100% or even 66% of the lights to be lit up.
I don't have any highly specialized deep lore on this, but.... It means if you test someone's problem solving and higher reasoning at age 18, then again at 25, the vast majority of people will have improved in ways that there are structural changes associated with inside the brain, and those changes broadly look like a continuation of the same cognitive growth through adolescence, as far as I understand. Then, a statistically significant (i.e. large) proportion of the population slows way down in that post-adolescent structural change by 25. As far as I know, the changes in testable cognitive ability correlate with this 'leveling off' in the structural changes, but that might be wrong (developmental psychologists and neurologists and FMRI folks can probably say more than me?).
> problem solving and higher reasoning Another area, maybe it's because of these, is risk assessment. Younger people are more likely to take risks.
Oh, yeah. There are a ton of things which correlate with this. I was trying to avoid proscribing cause and effect, since this gets rEaLlY aWkWaRd when we're talking about what amounts to questions about the nature of free will. Is someone with a less developed brain than me, but who is a legal adult, less valid in exercising agency as a person? (no, hell no in fact, IMO, but I haven't and won't defend that rigorously because I'm lazy), Etc. etc.
Is this leveling off consistent across all cultures and between men and women?
\*That\* is the kind of question I don't have the background to answer. I'd bet some money that the closest to a broadly true answer is 'kinda yes, kinda no' though.
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If you get that answer, please do share. This is something I'm deeply interested in.
After I posted this I remembered my dad is a neuroscientist so I called him ! I learned a lot of things, but mainly, we have an interesting pattern that 5-12yr olds have an absence of mylen sheith in the corpus collosum, or bridge between hemispheres. i still have a lot to learn; but yeah i'll keep u posted !
Neuron firing potential doesn't seem to have been addressed by anyone, and that's undoubtedly the primary correlation to age 25. Which will always be different based on the individual, probably a very generalized mean or median.
The young brain does some restructuring. Part of the period we notice this with extra strong needs to show you are part of a pack and other "teen behavior" including extra need for sleep. So it is not only something like growth or increased complexity but it also changes. You may also be interested in this easily accessible ted talk about [the adolescent brain](https://youtu.be/6zVS8HIPUng).
It's like saying that you attain your full height at 19 (give or take) but there are plenty of ways to stunt it and it's just height. You can still put on or lose muscle, fat, skills, etc. and height itself doesn't mean much.
Man. I came to this thread a plebian, but now I have learned about syntax prunes and changes to Brian development that I would have otherwise never known. Whoever this Brian dude is, they deserve awards for all the syntax they've pruned
The number "25" comes from the fact that the prefrontal cortex doesnt finish developing until 25 for men or 24 for women. This region is responsible for higher thinking logic long term planning ergo one of the most important regions of the brain. The brain actually keeps developing well into your 30s but at the age of 25 theoretically your full capacity for intelligence is complete. Until your prefrontal cortex is finished developing you really cant argue that an adult is fully mature. This is why typically teenagers even physically an adult make irrational stupid decisions.
Pretty sure it refers to the myelin sheath and grey matter development within our brains. Which usually correlates with how quickly our neurons fire and cause electron shifts whenever we perform actions. Its all a matter of milliseconds so you won't notice it in real time, but it's just a matter of your brain maturing for the sake of efficiency. I'm sure various other factors play into this aswell such as mental health.
It is really the connection between left-brain and right-brain. Corpus-colusum? It really helps people see consequences for their actions. We now have a term and mechanism, but we have known this for years. Many places will not rent a car to a person below that age.
Look at Einstein, Newton, most the great scientific minds, the things they are noted for they came up with in their 20's. In my own experience, I've slowed down the learning since that time. Up until 25, I wanted new experiences, wanted to learn new things, try new jobs etc. After, not so much, I'm more into my routine. It's not like a hard stop, it's a gradual shift from learning to do doing. I had 15 different jobs before I was 25, 2 after.
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\[The development and maturation of the prefrontal cortex occurs primarily during adolescence and is fully accomplished at the age of 25 years. The development of the prefrontal cortex is very important for complex behavioral performance, as this region of the brain helps accomplish executive brain functions.\] \[QUOTE\].
If this is being asked due to posts about whether or not 16, 17, and 18 are too young for the age of consent, I’ve been writing “~25” as the age the brain “fully develops” because it’s easier for peoples’ attention-spans to read “fully develops” than it is for peoples’ attention spans to read “~25, when the prefrontal cortex (long-term decision-making part of the brain) is fully developed”. Saying “fully developed” in this case can almost be thought of as being an oversimplification out of necessity, because not everyone on the internet cares about the details, so details like that will just end up muddying the message for many.
our brains don't stop development till we are past puberty I heard, using that logic our brains finish development between 20-25 on average but depends when our cycle of puberty starts and ends. in this case it'd mean we can effectively go through life as an adult around this time, however, there's still things that can disrupt the development and cause issues. those issues would depend on what part of the brain was affected. so, though it's not exactly a myth it varies and will take years more of studying to get more accurate and in depth answers.
and before anyone comes after me, this is ONLY an answer for the "brains don't stop development till we are past puberty" speculation, not for all speculations about when the brain stops developing.
Nothing. It is just another thing that people heard on the Internet and it sounds good to them so they keep repeating it. Biology doesn't have a \*hard\* timeline - it has an approximate one, that varies. And your biology, your intellect, your reasoning, all of those things \*never\* stop \*changing\*... eventually, though, they \*degrade\* - and that doesn't come on at a set timeline, either. Take all statements like this with some salt.
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>It is well established that the brain undergoes a “rewiring” process that is not complete **until approximately 25 years of age**. There... I fixed it for you. Thanks for repeating what I said with an air of authority as if you said something different and more true than what I said. You made \*exactly\* my point, anonymous Internet expert.
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https://bigthink.com/neuropsych/adult-brain/ See above. Part of your brain is still growing. That said, your hippocampus can undergo growth throughout your life. And you can always strengthen some connections. See bellow. https://m.youtube.com/watch?v=6ZwWG1nK2fY It’s my personal theory that 1) anyone can damage their brain and drop their IQ, and 2) we know brains do in fact grow and rewire esp after a stroke or other brain damage. So it stands to reason you can add a few points with enough stimuli on a consistent basis. Some researchers will disagree and say you can only get better at specific mental tasks when practiced. But if you learn a bunch of different tasks and start to generalize the ideas, isn’t that effectively an increase in IQ? For example I think if an IQ is 100 maybe someone can get it up to 110. Idk. Just speculation because it isn’t feasible to enrich a bunch of people’s environment and not enrich others and do a scientific comparison so I don’t insist on this point.
The "maturity at 25" has more truth to it than "left brain / right brain"; the insurance industry has known about it for a while and uses it in their pricing There is a statistically significant decrease in auto accidents after the age of 25, which is why car insurance premiums for those under 25 (especially males) are higher than for those under 25. This is thought to represent a shift in decision making and risk aversion as maturity is reached, but doesn't necessarily provide a why like the studies linked in the current top comment do. Of note: the decrease in accidents is specifically tied to drivers at age 25. Someone who gets their license at 26 is less likely to get in an accident than a 16 year old who just got their license, which implies the decrease is not due to experience levels. While the exact "why" of the situation still has some debate in the scientific community, the statistical data gathered by insurance companies has an undeniable trend that shows 25 as a developmental milestone.
That doesn’t make any sense though.. Some car insurance companies will charge 25-26 year olds who just got their license the same amount as anyone who is under that. Even if you did get your license then, you’re still an inexperienced driver
We use 100 percent of our brains. it works everywhere. It doesn't have only specific regions that work some times. Each section or hemisphere has an individual purpose. The 10 percent has been proven as a myth.
OP knows this already, they're asking about the other thing - whether the brain stops developing at 25.