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Behavior & the Teen Brain

Adolescent brain and behavior

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.

Physical Coordination
[Cerebellum]

The cerebellum, located at the back of the brain, controls physical coordination and the processing of sensory input.

Emotion
[Amygdala]

Teens can be extremely passionate. This part of their brain is slightly over-reactive, often leading to burning, expressing emotions.

Motivation
[Nucleus Acumbens]

You may not think of your teen as highly motivated, but imagine what he’d do for that Xbox! Without a fully developed Prefrontal Cortex, controlling impulses can be a real challenge.

Judgement
[Prefrontal Cortex]

This part, which controls reasoning and impulses, isn’t fully developed in teens until about age 25.

You may have noticed some of these effects:
  • Difficulty holding back or controlling emotions
  • A preference for physical activity
  • A preference for high-excitement and low-effort activities (video games, sex, drugs, rock’n’roll)
  • Poor planning and judgement; raely thinking of negative consequences
  • More risky, impulsive behaviors, including experimenting with drugs and alcohol
These parts are shouting but…
…this part is not quite ready to referee.
Physical
Coordination!

Emotion!

Motivation!

Judgement

Slide marker to see MRI images showing brain maturation from ages 5 to 201
5 10 15 20

% of Gray Matter
Red shows less maturity
Blue and Purple show more maturity

1Paul Thompson, UCLA Labratory of Neuroimaging, 2004

Memory

The memory center of the brain (the hippocampus) in teens who have already abused alcohol is 10% smaller than normal, and they have lower memory scores.1

Pleasure

Under the influence, the brain’s reward circuits (the dopamine system) get thrown out of whack. This causes a teen to feel in a funk when not under the infuence — and going back for more only makes things worse.

Coping and life-skills

While teens are undergoing a massive growth spurt, using drugs and alcohol may disrupt their brain development in unhealthy ways, making it harder for them to cope with social situations and the normal pressures of life.

1Nagel, Schweinsburg, Phan & Tabert,
“Imaging psysiologic dusfunction of individual
hippocamal subregions in humans
and genetically modified mice,”2005.

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, rock ‘n’ roll),
  • 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.

Next Step: Drugs & teen moods