No, Your Brain Doesn’t Stop Growing at 25

Growing up, there was always an idea of a race to 25. It was commonly believed that that was when it would become harder to learn. Many pressured moments before that fateful date were spent cramming my head with knowledge before that dreaded “deadline”. It was an unending marathon to compile soft skills and hard skills — and all the skills in between — otherwise, they said, the back portion of my life wouldn’t be fulfilling. I wanted to prepare for a meaningful life — a successful one, too.

When I finally reached 25, my prefrontal cortex was complete and I was finally self-aware (Yippee!). In theory, I was done with education and ready to apply my hard-earned knowledge.

But, the learning never stopped, the subjects only shifted. Instead of academic lessons, it became learning how to function in society, how to be an adult after spending time in college. Have you noticed that learning didn’t stop at 25? Many people find that their most significant personal growth happens later in life. The learning doesn’t have to stop as long as we carry on wanting to educate ourselves.

Research shows that the idea of 25 as a magical brain maturity age is a bonafide myth. In truth, brain development and learning can be a lifelong experience with the right practices. Scientifically speaking, we can all keep learning until we drop. We only have to try.

The Origin of the Myth

As many modern myths are wont to do, this lovely one started with a misrepresentation of scientific studies. It all started when studies began using the incredible new power of fMRI brain imaging. In the 1990s, this technology was the hot new tool to use and was increasingly used over the next couple of decades as part of the study method in a wide variety of neuroscience papers. A good selection of those studies focused on brain development, specifically looking at the structures of the brains of teenagers and young adults.

From these studies, researchers in the neuroscience field discovered that “as children grew older, the prefrontal cortex, a brain area responsible for cognitive control, experienced physical changes. In particular, they found that white matter — bundles of nerve fibers that facilitate communication across brain areas — increases, suggesting a greater capacity for learning.” Those same studies, which took in an age group of adolescents, saw continued changes in their entire study group tested: from their youngest participants to their oldest members of the study: 25-year-olds.

Routinely, this age group was the oldest in these sorts of adolescent brain development studies in the field, not because they were a particularly compelling age that showed any known drastic change in the brain, but, as mere coincidence. One researcher, psychologist Larry Steinberg, who contributed to this grouping of research, when asked about the magic number ‘25’ by Slate in 2022, simply explained that he did not know why he and others picked 25 as the end parameter. “It’s a nice-sounding number? It’s divisible by five?” was his reasoning for the study cut-off in his own paper.

However, once these scientific studies were published, media outlets picked up the information and simplified it to better suit a general audience (as is needed with a field as complex as neuroscience). Unfortunately, that same complexity which required simplification led to misinterpretation by the sources that reported on it, akin to someone passing along the wrong message in a game of telephone.

Once out in the world, the myth picked up speed, finding its way into books, blogs, and social media posts. The articles that lacked the nuance the study contained were made into quick fun facts, sensational headlines, and 280 character or less tweets.

And then, a few years down the line, enter TikTok. The platform, as I’ve mentioned previously in the article, “TikTok Keeps Diagnosing People with Neurodiversity. Is it Valid?”, doesn’t select videos to spread across the platform when they’re particularly accurate or dutifully researched. The algorithm is a game of shock and sensationalism. It pushes forth videos that are engaging to users, ones that prompt lots of comments, angry or not. Once a factoid makes its way into pop science spaces, non-experts and experts alike are given a voice — and the engaging videos that fit the short timeframe often win out. This format naturally causes a need to simplify lengthy topics — making the platform a great breeding ground for scrubbing the nuance off of the results of a study.

What the Research Really Says

“Despite its prevalence, there’s no actual data set or specific study that can be invoked or pointed at as the obvious source of the claim that the human brain stops developing at age 25”, wrote BBC Science Focus in April 2024. The article and its writer focus on how variable each individual brain truly is. Yes, it is achievable to have one’s brain stagnate should the owner of it so choose, there are anecdotal cases of individual brains that continue development long past that date. In short, it is difficult to determine a universal “maturation date”, when where “‘developing’ and ‘maturation’ ends is tricky to pin down. The human is essentially an assemblage of many different regions, of varying degrees of complexity, maturing at different rates.” In short, the researchers are still hashing this bit out.

And, even with there being a potential for a findable “full maturation date” of the brain in the future, there is currently no evidence that suggests that the brain stops adapting and growing at any stage of life.

There is some notable evidence of the opposite: neurogenesis, the creation of new neurons, is a common part of the mammalian brain throughout life, even for us adults — though the locale of growth does seem to shift. Lifelong learning is one of the traits we have in common with many others in class Mammalia. Turns out, scientifically, it may be feasible to teach an old dog new tricks. This concept is still under debate within the community, however.

But, the world of pop science, to fit into the short form video format, drastically simplified a rather complex and confusing system — one that isn’t fully researched yet even by the experts. The complexity of neuroscience requires much context and an understanding of the nuance that pairs with it. This oversimplification has real-world consequences we must be aware of.

The Impact of the Myth

Not only is the myth demonstrably false, but it can also be actively emotionally and mentally damaging to those who believe it. The idea that the brain is complete at a certain age limits the potential of the self, causing anxiety leading up to it and a sense of helplessness afterward. It displays those under 25 as less or underdeveloped. On the other hand, it displays those over 25 as complete, fixed, and stuck as they are — flaws and all.

Consider the effects of such a belief. Think of the folks who, despite intellectual promise, cease their education after 25 because they missed their window, the people who believe they cannot meaningfully improve their mental health because they experienced trauma too late, the workers who decide against major career changes that would multiply their happiness tenfold because they have no confidence in their cognitive abilities. These are the people who subscribe to the myth, who miss out on growth because of their lack of belief in it.

If the myth goes too far and permeates society, there is a risk it, too, could affect policy, altering age restrictions and age-based responsibilities, allowing for barring privileges like voting to young people who are more than well-equipped to make political decisions for their future. The belief could also contribute to ageism, seeing 18–24-year-olds as not fully complete in development, uniformly not wise enough to make decisions for themself. This, simply, isn’t true.

The Incredible Science of Brain Development

We still don’t fully understand the brain yet but, the past century of research has gotten us impressively far in that journey. The cellular and chemical aspects of the brain are well-researched at this point, with a decent collection of knowledge about how brain cells develop and speak with each other, what chemicals do what in our brain, and how many different substances and diseases can impact brain functioning. There are still many questions left over we have yet to discover the answers to. Lifelong brain development patterns are one of those sections of neuroscience yet to be fully uncovered. We don’t have the true answer yet and the myth of ‘25’ is a classic case of jumping the gun.

As with most scientific revelations, new discoveries and answers often lead to additional questions and, occasionally, de-simplification of aspects of something once thought solved and simple. There’s always a chance of a revelation that may alter even the “knowns” we’re aware of in neuroscience. It’s truly an inspiring thing to see the scientific engine at work in this way.

With all that said, here’s how we currently understand lifelong brain development: The brain is an organ in a nearly constant state of adaptation. It is a population of neurons whose pathways strengthen with use and weaken with disuse. The plasticity of this system does not decrease with age. Some research even points to plasticity generally increasing as we age, albeit in different brain regions than in younger individuals, and it can also obe more dysregulated. But, synaptogenesis (the formation of pathways between neurons) and synaptic pruning (eliminating pathways between neurons) could be a lifelong ordeal we can endure if we so choose.

There seems to be a fair bit of false equivalency between brain size and the dynamic nature of the brain and its ability to grow. Those milestones we know of in adolescent brain development speak to the former, not necessarily the latter. But, though size doesn’t see as great of a difference after the mid-twenties of someone’s life, the ability of the brain to change its structure doesn’t even begin to plateau by 30. As of right now, the oldest person tested on such studies was 30 so, we genuinely aren’t yet sure about there being a universal point of plateau.

The prefrontal cortex is no exception to this rule. Though, yes, it does mature at a slower rate than many other parts of the brain, it isn’t done at 25. It hits maturity and an adult size at that age that mostly stays the same throughout life, certainly, but the pathways within continue to modify and strengthen and weaken like a mesmerizing light show- as long as we continue producing that light.

In truth, the rate of neuroplasticity is at least partially determined by how much effort we put into it, not the age group we’re in. Though it isn’t yet certain, and I could totally be doing my own version of ‘jumping the gun’ here, the slowing of cognitive ability could be a side-effect of our culture and how we treat those who are aged, and how many people cease attempting to learn after they leave the world of formal education, instead of the number of years we’ve circled the sun.

--

The brain does not stop development at 25 — intellectual growth and development is a lifelong process — one that we can continue to access past the spring of our lives if we’re willing to put in the effort. The myth that there’s a certain magical age where we’re done with all that ‘learning and growing junk’ is simply, demonstrably false. Living a life that promotes continual brain development is possible. As humanity discovers more and comes closer and closer to approximating truth, we can work to adapt to it, change our perspective, and keep our minds acting as a dynamic ecosystem of thought.

But, readers, along with encouragement to continue learning, let this article be your reminder to not take scientific fun facts from influencers and others as undeniable, inscrutable facts. We all make mistakes, improperly simplifying, misunderstanding, and occasionally, misrepresenting the truth we believe with poor word choices. To err is human, but learning from erring is divine.

Thankfully, we can learn from that mistake, no matter how old we are. The pursuit of knowledge has no age limit.

--

Cross-Posted from Medium. Follow My Account for new articles about science every other Friday!