Dr. Frances E. Jensen, M.D., author of The Teenage Brain, explains that the human brain won’t fully mature until almost 30 years of age. Today, we will explore why this is important to understand about ourselves, and also why we shouldn’t become fixated on this timeline.

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The age-old saying; ‘You can’t teach an old dog new tricks’ is a phrase we will hear referenced throughout our lives as a cheeky response to why adults have a tendency not to change their habits. Certainly, we become a product of our environment and the rat race of life, but is that the total cause and effect?

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Scientists have studied the brain's growth patterns for years and have proven through MRI scans that the shape and size will continue to evolve throughout our 20s. Some Drs. maintain that this developmental process leads well into our 30s or 40s, but for a safe assessment and the basis of this article, we will stick with the notion of full brain development by the approx. age of 30 years old.

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Taking a step back, the brain reaches its adult volume before we hit our teen years. The changes in neurons (which the brain is comprised of) will then develop over the next couple of decades. Years of molding and shaping will transpire throughout this duration, as neighboring neurons become separated or moved by newly formed links between other disparate portions of the brain. Over time, these formations slow in development but at different rates depending on the specific brain area (a sign of maturing in stages).

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The occipital lobe, for example, will be fully formed by about the age of 20. This area is located towards the rear of the brain and is responsible for visual perception (color, form, motion). The prefrontal cortex, on the other hand, is the portion of the brain witnessed as the last to fully develop. This area intelligently regulates our actions, thoughts, and emotions. It tends to align with our concept of ‘maturity level’, and helps explain why we may witness a greater sense of self-control, or ‘growing up’, with age. One caveat to the prefrontal cortex while still developing: teenagers might rely on a portion of the brain called the amygdala to make decisions. The amygdala is associated with emotions, aggression, impulses, and instinctual behaviors. Without a fully formed prefrontal cortex, reasoning and problem-solving might lean more toward an emotional decision versus a logical one.

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Regardless of where we are in our brain development, there is no substitute for experience. The more information we become exposed to, the more neurons fire and connect in new patterns. Naturally, once the brain is fully formed, we can base decisions on a heightened sense of reason, but this does not serve as an excuse or detriment to our abilities prior. Understanding how we develop over such a duration of time is why it’s important to realize the things we do in our 20s still play a large role in the growth of our brain.

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All the standard health concerns still apply: ample sleep, eating right, staying away from drugs, etc. One large change to consider, however, is the sudden introduction of a now-legal substance at the age of 21: alcohol.

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In the US, by the age of 21, you have been legally named an adult for three years. During this time, you've been capable of having entered the military, college, and/or most professional occupations. You’re now granted the right to purchase, possess, and consume alcohol, yet you’re still years away from a fully matured brain awaiting completion of logical and rational thinking. This is not to discount our legal system or the drinking age by any means, but rather a call for a heightened sense of accountability to look after ourselves and others.

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We live in a country that grants us rights and independence to make good decisions. We’re capable of doing so at all ages and stages of life, but there will be temptations and challenges along the way. We must be aware of our potential vulnerabilities and the possible impacts of making poor decisions.  

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The rate of brain development is not within our control; this will happen on its own. What we can control, however, is how we support this developmental period and help to stimulate brain growth. Over-taxing our bodies and under-utilizing our minds, combined with poor practices (such as excessive use of substances), will impede our growth potential. Prudent actions within these formative years are essential for optimizing our future.

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The future is not so distant, and as we enter the later years past our 40s, 50s, and 60s, our brain is still eager and firing on all cylinders. Studies show that into our 90’s we’re still generating substantial neurological activity (with plenty of brain capacity for learning and taking on new responsibilities). Our bodies may slow, but our minds will propel us forward. A fully formed brain is just the start to exploring all that we seek. With increasing age, we can apply new information to the existing data we have already acquired. This shows us that our mind is built for knowledge gain and that we never stop learning or finding new ways to learn.

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Considering our brain won’t fully mature until approx. 30 years of age, this provides us quite the runway to decide who we want to be as adults. Once into our adulthood, we should also recognize we’re now poised for even greater challenges and success. The reality is that we never stop preparing for our future, and in these preparation efforts, we continuously learn about ourselves and our surroundings. Challenge your development process and lead by example. After all, your actions will impact the development of those who watch you. Are you ready to discover the power of your mindset?

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