When Does Your Brain Stop Developing?

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Practical Psychology

Is your brain fully developed? 

The answer actually depends on your age. Over the past few decades, neuroscientists have used the idea of brain development and maturity to determine what makes a “child” an “adult.” Knowing this, you may be surprised to learn when the brain is fully developed. We are continuing to learn more about brain development every day, learning most recently that the brain is always changing.

When Does Your Brain Stop Developing? 

Brains are fully developed by the age of 25 and brain development begins as soon as a fetus is conceived. Factors like psychoactive drugs and even diet influence this development. Before and after the age of 25, the brain may change and re-organize through the process of neuroplasticity.

How the Brain First Develops

Before we answer the question about how the brain stops developing, let's look at how it starts. The brain begins to develop while a fetus is in utero. What starts as a simple neural tube grows into the forebrain, midbrain, and endbrain. These sections become five sections and then start to take the shape of an "adult" brain.

What Affects Brain Development During Pregnancy?

Currently pregnant and worried about your child's brain development? Do not worry. Take the same supplements and avoid the same substances that you would if you were concerned about your own brain development! Consuming omega-3s and folate will encourage development. Smoking and alcohol use may cause harm.

Brain Development After Birth

We know that each part of the adult brain seems to take on different tasks. Wernicke's area, for example, is crucial in language development. Vision is processed in the visual cortex at the back of the brain. This only happens after data about what we see moves through other regions with their own responsibilities. Are these specific areas formed when a baby comes out of the womb? Likely no, and it's not easy for scientists to understand what is innate and not.

Some studies suggest that infants may be born with the ability to identify and categorize faces. These studies still cannot say with certainty what skills are innate in all humans at birth. They can say that it develops at a very young age.

How Fast Does the Brain Develop During Infancy and Childhood?

A baby's brain is 1/4 of the size of an adult's brain, but grows to full size by the age of 5! The first few months of a baby's life are crucial to growth. By the time a baby reaches their first birthday, their brain will have doubled in size.

Pretty cool, huh?

Now, you may be thinking to yourself, "There's no way a five-year-old has the same size brain as an adult!" What's important to know is that the size of the brain does not matter as much as the connections within the brain. Babies are born with the same amount of neurons in their brains as an adult. New experiences form connections between these neurons, helping the baby develop certain skills and specialized areas of the brain. The more complex these connections, the more a baby, child, and then adult learns.

At What Age Does Brain Development Stop?

New connections are being made constantly throughout a young person's life and well into their 20s. Neuroscientists believe that the brain isn't fully developed until a person reaches 25. The late development of the prefrontal cortex may explain how young adults behave.

The prefrontal cortex is a large section at the front of the brain. Connections made in the prefrontal cortex influence logic and rationality. When adults with fully-formed brains make a decision, the prefrontal cortex is lit up.

Teens, with their not-fully-developed brains, make decisions differently. When making decisions, teens are more likely to rely on their amygdala. This part of the brain is crucial in processing strong emotions. Rather than using logic to make decisions, teens are more likely to rely on their emotions. And that's why teens often make silly decisions that they make.

Why then, can you rent a car at 25, but drink alcohol, enter the military, and vote before your brain is fully developed? That's a question for an entirely different blog post!

What Affects Brain Development?

The factors affecting brain development may surprise you:

  • Sensory experiences
  • Motor experiences
  • Psychoactive drugs and alcohol
  • Gonadal hormones
  • Parent-child and peer relationships
  • Stress
  • Gut flora
  • Diet 
  • Injuries 

Can Alcohol Affect Brain Development?

Yes. Alcohol can negatively affect brain development in utero and throughout a person's life. A night of binge drinking can damage and completely wipe out cells in the hippocampus. Not only does this affect the individual cell, but all the potential connections to that cell.

Can Antidepressants Affect Brain Development?

“Psychoactive drugs” is an umbrella term that includes controlled substances like caffeine, nicotine, marijuana, antidepressants, and pain medications. Not all of these substances affect brain development in the same way. Consuming marijuana as an adolescent, for example, is likely to delay the development of the prefrontal cortex where rational decisions are made. But studies on SSRIs (antidepressants) don’t come to one conclusion or the other. If you are considering going on antidepressants, reach out to a medical professional to discuss your options. 

Brain Development After Injury

There are miraculous cases of people who have suffered brain injuries at a young age but regain the ability to walk, talk, or do other things that they couldn’t do post-injury. How does that work? 

There are many theories that explain how these “miracles” can happen. Some suggest that brain cells are not destroyed during a brain injury, but simply revert back to an “embryonic state.” It’s like if you were injured and all of a sudden became a child again. Yes, you would face many setbacks, but through growth and development, you could get back to where you were before the injury. 

Other theories suggest that neuroplasticity takes over during an injury. Through neuroplasticity, the brain re-organizes itself to adapt to the post-injury brain. 


We learn things way beyond the age of 25. Sure, learning a language may be harder for a 25-year-old than a 2-year-old, but it's still possible. Our brains store memories, come to different conclusions and may see the world differently over the decades. How do we do this with a fully developed brain?

Neuroscientists answer this question by introducing the concept of neuroplasticity. Neuroplasticity, or brain plasticity, is the idea that our neurons continue to change and re-organize throughout our lives. Every time we learn something new or form new relationships, we have the potential to rewire our brains and change the way we see the world. Not all plasticity is good, so stress and injury can reorganize the brains in harmful ways, too. 

Neuroplasticity is crucial to supporting the idea of growth (vs. fixed) mindset. With determination, patience, and a little bit of re-organization here and there, it is possible to expand your thinking and learn new skills. So take care of your brain! Even if you are over the age of 25, you can influence the change and organization of your brain in many ways. The brain may stop developing and growing, but it never stops changing. Keep learning, stay healthy, and embrace neuroplasticity!

Reference this article:

Practical Psychology. (2022, April). When Does Your Brain Stop Developing?. Retrieved from https://practicalpie.com/when-does-your-brain-stop-developing/.

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