Teenage Brain

Adolescent Brain Development

Scientists now know that the brain is getting reorganized in a big way during the teenage years. This is a time of huge opportunities — and risks.

Everyone knows the importance of guiding and nurturing toddlers, whose brains are developing at warp speed. But what about the development of the teen brain? We’re now learning that adolescents go through a similar wave of major development. From ages 13 to about age 25, a pruning and strengthening process is happening in their brains. During that time, the brain cells and neural connections that get used the least get pruned away and die off; those that get used the most get stronger.

This new knowledge about adolescent brain development explains why it’s so important for parents to encourage teens to have healthy activities: The more time your teen spends learning music, the stronger those brain connections get. The same is true of the connections she uses for playing video games, mastering a sport, or watching TV.

Ironically, this period — when the brain is rapidly changing and most vulnerable to outside influences — is when teens are most likely to experiment with drugs and alcohol. Why? One reason may be because the brain region that’s responsible for making complex judgments (the Prefrontal Cortex) isn’t fully mature, and therefore is prone to being overpowered by the emotional or motivational regions that are more mature. Scientists believe this aspect of teenage brain development explains why young people sometimes use poor judgment and don’t have good impulse control.

Because of the huge changes happening in the teenage brain, it’s possible that a decision your teen makes now may affect him for life. (Brain scans, for instance, have linked alcohol abuse with decreased memory functioning.) Just sharing that fact with your teen may help him to stop and think before he takes any chances, and even inspire him to make more healthy choices.

The Adolescent Brain and Behavior

Judgment Last to Develop

The area of the brain that controls “executive functions” – including weighing long-term consequences and controlling impulses – is among the last to fully mature. Brain development from childhood to adulthood looks like:

From early adolescence through their mid-20s, a teen’s brain develops somewhat unevenly, from back to front. This may help explain their endearingly quirky behavior but also makes them prone to risk-taking.

The parts of the adolescent brain which develop first are those which control physical coordination, emotion and motivation. However, the part of the brain which controls reasoning and impulses – known as the Prefrontal Cortex – is near the front of the brain and, therefore, develops last. This part of the brain does not fully mature until the age of 25.

It’s as if, while the other parts of the teen brain are shouting, the Prefrontal Cortex is not quite ready to play referee. This can have noticeable effects on adolescent behavior. You may have noticed some of these effects in your teen:

  • difficulty holding back or controlling emotions
  • a preference for physical activity
  • a preference for high excitement and low effort activities (video games, sex, drugs,)
  • poor planning and judgement (rarely thinking of negative consequences)
  • more risky, impulsive behaviors, including experimenting with drugs and alcohol

The development of the adolescent brain and behavior are closely linked. In a wink, hormones can shift your teen’s emotions into overdrive, leading to unpredictable – and sometimes risky – actions. Unfortunately, developing brains may be more prone to damage. This means that experimentation with drugs and alcohol can have lasting, harmful effects on your teen’s health.

  • Research shows that alcohol abuse during the teenage years negatively impacts the memory center of the brain (the hippocampus).
  • The use of drugs and alcohol may also disrupt the development of the adolescent brain in unhealthy ways, making it harder for teens to cope with social situations and the normal pressures of life.
  • Moreover, the brain’s reward circuits (the dopamine system) get thrown out of whack when under the influence. This causes a teen to feel “in a funk” when not using drugs or alcohol – and going back for more only makes things worse.

It is important to urge your teen to take healthy risks. Not only will participation in constructive activities – such as athletics or the arts – help him or her form positive lifestyle habits, it will help your teen’s forebrain develop as well.

Effects of Drugs on the Brain & Teen Moods

Finding ways to satisfy needs and desires is part of life. It’s one of the many skills that is being fine-tuned during the teen years. When a teen takes drugs, it can interfere with his natural ability to feel good. Here’s how drugs affect the brain:

The brain is made up of billions of nerve cells. Nerves control everything from when his heart beats to what he feels, thinks and does. They do this by sending electrical signals throughout his body. The signals get passed from nerve, to nerve by chemical messengers called “neurotransmitters.”

For example, some of the signals that neurotransmitters send cause a feeling of satisfaction or pleasure. These natural rewards are the body’s way of making sure we look for more of what makes us feel good. (For instance, when we eat something tasty, neurotransmitters tell us we feel good. Seeking more of this pleasure helps to ensure we don’t starve.) The main neurotransmitter of the “feel-good” message is called dopamine.

All drugs of abuse overload the body with dopamine — in other words, they cause the reward system to send too many “feel-good” signals. In response, the body’s brain systems try to right the balance by letting fewer of the “feel-good” signals through. As time goes on, the body needs more of the drug to feel the same high as before. This effect is known as “tolerance.”

The effects of drugs on the brain don’t just end when the high wears off. When a person stops taking a drug, his dopamine levels are low for some time. He may feel down, or flat, and unable to feel the normal pleasures in life, even when meeting a basic life need. His brain will eventually restore the dopamine balance by itself, but it takes time — anywhere from hours, to days, or even months, depending on the drug, the length and amount of abuse, and the person.

Because they have an over-active impulse to seek pleasure and less ability to consider the consequences, teens are especially vulnerable when it comes to the temptations of drugs and alcohol. And because the internal reward systems are still being developed, a teen’s ability to bounce back to normal after abusing drugs may be compromised due to how drugs affect the brain.


Image – National Institute of Mental Health; Paul Thompson, Ph.D., UCLA Laboratory of Neuro Imaging

National Institute on Drug Abuse (NIDA), Drugs and the Brain

Nagel, Schweinsburg, Phan & Tabert, “Imaging Psysiologic Dysfunction of Individual Hippocampal Subregions in Humans and Genetically Modified Mice,” 2005


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