How drugs & alcohol affect the teenage brain

Research indicates that brain development is still in progress during adolescence, with significant changes continuing into the early 20s. Immature brain regions place teenagers at elevated risk to the effects of drugs and alcohol.

The developing brain of the teenage years may help explain why adolescents sometimes make decisions that seem to be quite risky and may lead to safety or health concerns. The juvenile brain is still maturing in the teenage years and reasoning and judgment are developing well into the early to mid-20s.

How the brain develops

Brain maturation tends to occur from the back of the brain to the front. So the front region of the brain, known as the prefrontal cortex, which is responsible for high-level reasoning and decision-making, does not become fully mature until around the early to mid-20s.

The prefrontal cortex is the part of the brain that enables a person to think clearly, to make good decisions and to control impulses. It is primarily responsible for how much priority to give incoming messages like ”Do this now” versus ”Wait! What about the consequences?” As Psychologist Laurence Steinberg sees it, a teenager’s brain “has a well-developed accelerator but only a partly developed brake.”

How alcohol and drugs affect the teenage brain

The prefrontal area, responsible for thinking, planning, good judgment, decision-making, and impulse control, undergoes the most change during adolescence. Researchers found that adolescent drinking could cause severe changes in this area, which plays an important role in forming adult personality and behavior. Damage from alcohol at this time can be long-term and irreversible.

The hippocampus, involved in learning and memory, suffers the worst alcohol related brain damage in teens. Long-term, heavy drinking causes teens to have a 10% smaller hippocampi. In addition, short-term or moderate drinking impairs learning and memory far more in youths than adults. Frequent drinkers may never be able to catch up in adulthood since alcohol inhibits systems crucial for storing new information.

Increased risk of addiction

Children who begin drinking at age 13 have a 45% chance of becoming alcohol-dependent. A person who starts drinking at the legal age of 21 has only a 7% chance of becoming addicted.

The brain rewards positive actions with feelings of pleasure so we want to repeat them. Alcohol and drugs hijack the brain by producing those “feel-good” brain chemicals, or neurotransmitters, from a harmful chemical, instead of a real experience.

If teens continue drinking, they will build a tolerance and have to consume a larger quantity of drugs or alcohol to produce the “feel-good” chemicals. Teens can begin to crave the high from the “feel-good” chemicals and become addicted.

Check out this post for 7 tips to keep kids drug and alcohol free.


“Having a scientific perspective on the biological challenges of adolescence will help you interact more objectively with your child, maintain your cool, and offer guidance that can improve his or her life.”

-Dr. David Walsh