Your Brain is Changing: Here's What's Happening

During adolescence, your body develops in ways you notice on the outside. Changes that you can’t see are also happening inside — such as to your brain. It probably won’t surprise you that changes in your brain can affect your mood, behavior, and mental health.

Inside the teen brain: Parts under development

Even though your brain reaches its full adult size by puberty, it keeps developing throughout your teen years and doesn’t fully finish until your mid-twenties. The forebrain, the biggest part of your brain containing the limbic system and parts of your cerebrum called the frontal lobes, goes through many changes during adolescence. Together, the limbic system and frontal lobes are responsible for emotions, memories, thinking, and logic.

Effects of brain development: Early adolescence

Changes in the limbic system and the frontal lobes of the cerebrum affect your reactions and decision-making.

In early adolescence, as your limbic system or “emotional brain” kicks into high gear, you may find yourself having strong emotional reactions, overanalyzing, or having difficulty reading other people. You might sometimes feel awkward or self-conscious, worrying about what other people think. This may in part be because your limbic system is basically in overdrive.

During this time, you’ll become better able to verbally express your feelings. You’ll start to form a sense of personal identity, wanting to establish some independence and spend more time with friends. You might find yourself drawn to the “rush” of immediate gratification or of taking risks. That’s because the limbic system is also responsible for feelings such as fear, pleasure, and perceiving rewards. Some choices, such as acting impulsively without thinking through consequences, can be dangerous, while other risks like taking on a new sport or a challenging class can be valuable. 

While your limbic system is in high gear, the frontal lobes of the cerebrum are still in low gear, waiting their turn to fully develop. This area, sometimes called your “rational brain,” is responsible for reasoning, planning, problem-solving, and controlling impulses.  The frontal lobes develop later than the limbic system, which is why it can be hard for your “rational brain” to calm down the “emotional brain” during early adolescence.  It’s like having a car with a powerful gas pedal and weak brakes.

Effects of brain development: Late teens and early adulthood

In early adulthood, the frontal lobes get their moment and begin to mature. They keep developing into your early-to-mid-twenties, with your prefrontal cortex, the very foremost part of the cerebrum, developing last.

As your “rational brain” develops, it communicates more effectively with your “emotional brain.” You’ll probably notice improvement at regulating your own emotions and reading how other people feel and act. You’ll get better at thinking ideas through, weighing risks and consequences, delaying gratification, making compromises, and prioritizing and planning for the long term.

For example, you might say no to staying up all night knowing you’ll feel lousy the next day, or have more patience to hear your parent(s) out and compromise when necessary. You may decide to study instead of scroll or procrastinate, or create a to-do list for achieving a future goal like raising your math grade or trying to make varsity. Essentially, your brakes become stronger and you learn to drive with more control.

What you can do to help your developing brain

Adolescence is a time of significant brain plasticity. While your environment and experiences always shape the brain, these influences are especially impactful during the adolescent period of brain development. Making choices like managing stress through problem solving, setting priorities, and not using substances can help protect your developing brain. Because mental health challenges can often first show up during adolescence, it’s especially important to build mental wellness habits, practice coping skills, learn to communicate intentionally, and lean on supportive connections with trusted adults and friends during this period.