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What Alcohol and Drugs Do to a Teen’s Developing Brain

Teenagers undergo many important, yet not always visible, changes during adolescence. As a parent, you’ve probably noticed that your teen sometimes seems emotional, impulsive, or irrational. This is in part because the developing brains of adolescents work differently than the brains of adults. The human brain is still maturing during the teenage years, and this process continues even into early adulthood.1


The teenage years also correspond with a time of experimentation in many youths. Teens may be tempted to try drugs or alcohol, often as a result of peer pressure or the desire to assert their independence. Alcohol and drug abuse can have a negative impact on brain development and can also lead to addiction. Talking to your child about the risks of drug and alcohol use is crucial, even if you don’t think your child is drinking or using drugs.

Brain Development

Adolescence can be one of the most trying and challenging phases of life for both parents and teens. The transition from adolescence to adulthood is accompanied by physical changes as well as social, emotional, and behavioral challenges.

This time can be confusing for parents. Perhaps your child displays an increased desire for independence, yet at the same time doesn’t take responsibility for their actions. Many of the changes you observe in your teen are attributable to the numerous neurological and cognitive changes and developments taking place in their brain. In fact, the rational part of the human brain isn’t fully developed until around the age of 25.2

During the teen years, the connections between the emotional and decision-making parts of the brain are still forming, and they don’t always develop simultaneously. This partly explains why your teen may sometimes have emotional outbursts, act irrationally, or make poor decisions.2

While the actual size of the brain doesn’t change much after early childhood, your teen’s brain goes through a number of significant developments throughout adolescence.3 Specifically, regions of white matter associated with intellectual functioning begin to increase in volume.3 Research has found that the typical improvement in skills, such as reading comprehension and language processing, that occur during the teen years are largely due to changes in white matter.3

The frontal lobes of the brain also mature in adolescence and young adulthood.3 In contrast with the amygdala—which develops in early childhood and is responsible for emotions and instinctual reactions like fear and aggression—maturity in the frontal lobes is associated with improved cognitive skills, problem solving, and control over impulsive decisions.3

Read More: Your Brain on Drugs

Rewards & Decision-Making

The prefrontal cortex is largely responsible for our decision-making processes. It serves an important role in moderating social behavior, informing our emotional responses, and developing some of our reward-seeking behaviors. To put it simply, adults think mainly with the prefrontal cortex, while teens still rely on the amygdala (the emotional part of the brain) for a relatively large amount of information processing.2 This can mean that teens are more likely to consider emotional factors such as social context and peer influences when responding to situations that involve a perceived reward.3

The reward pathway, especially the neurotransmitter dopamine, is important in discussing teen drug and alcohol use. Dopamine is associated with the feelings of reward and pleasure we receive from activities such as hugging a loved one or eating a hearty meal.

Many drugs of abuse are associated with an increase of dopamine activity in the brain, which in turn leads to the euphoric “high” associated with these substances.4 Relative to their adult counterparts, teenagers are more prone to emotional rather than rational decision-making. This can make the pleasurable feelings associated with drugs and alcohol highly reinforcing and may lead them to continue using despite the risk of negative consequences.


Substance Use Effects

Alcohol and drug abuse may interfere with adolescent brain development, which could translate to long-term cognitive changes in young substance users.

Studies have shown abnormalities in brain structure and function among youth who are heavy alcohol users.5 Researchers found that adolescents who were heavy drinkers displayed deficits in memory, attention span, and information processing, even after periods of monitored abstinence.5 Teens who used marijuana regularly displayed similar results, including decreased performance on tests that measured cognition, memory, and other important brain functions.5

For teens, this could mean academic ramifications that persist into adulthood and their professional careers.5 Heavy drinking during adolescence has been hypothesized to have a negative effect on the hippocampus, the area of the brain responsible for processing long-term memory and handling emotional responses. People who drank heavily or were highly dependent on alcohol as teenagers were shown to have smaller hippocampal volumes in MRI studies.5

Treating Addiction & Mental Illness

Teen Substance Use

Preventing teen substance use is one of the best ways to avert negative neurological consequences and, potentially, addiction later in life. The earlier someone starts using drugs or alcohol, the more likely it is that they will develop an addiction.6 In fact, 9 out of 10 people who abuse substances started using before the age of 18.6 Teens who start abusing drugs or alcohol before the age of 15 are nearly 7 times more likely to develop an addiction than people who start using after the age of 21.6

Statistics on teen substance use and abuse are provided yearly through the Monitoring the Future (MTF) study, which is funded by the National Institute on Drug Abuse (NIDA). This study examines trends and behaviors regarding illegal and legal drug use among American students in grades 8, 10, and 12.

According to the most recent results (2016), the use of most illicit drugs and the illicit use of prescription drugs is declining among survey respondents in all age groups.7

Stimulants, Alcohol, & Marijuana

Despite this overall decline, the use of bath salts—a synthetic stimulant—did show a significant increase among students in the 8th grade from 2015 to 2016, but this rate was unchanged in the other grades.7 During the same period, students in 8th grade also displayed an increased use of cold and cough medicines to get high, but the rate of use was unchanged in the other grades.

The effect of these newer drugs on adolescent brain development has yet to be extensively researched. They are, however, associated with other dangers such as overdose, psychological conditions, and risk of injury due to accident.

The MTF study reports that students seem to have relatively accepting attitudes toward marijuana use, but overall marijuana use has actually declined slightly among 8th and 10th graders from 2015 to 2016. Cannabis use remained constant in 12th graders for this same time period.7

Alcohol use among adolescents also declined. The study reports that 6 out of every 10 students (61%) have had more than a few sips of alcohol by the end of high school, and about a quarter (23%) have done so by 8th grade.7 Almost half (46%) of 12th graders and 9% of 8th graders in 2016 reported having been drunk at least once in their life.7

Overdose Risks

Despite the apparent decline in overall teen drug use, teen overdose death rates have been on the rise. The most recent statistics showed that the drug overdose death rate among teens increased 19% from 2014 to 2015.8 Most of these overdoses were unintentional, meaning that the adolescent was not intending to self-harm or commit suicide. The overdose death rates were highest for opioids (specifically heroin) among teens aged 15 to 19.8

It is crucial to talk to your child about the risks of drug abuse, even if you don’t suspect that your teen is drinking or using drugs. Teens who experiment with alcohol or drugs or combine substances may not be aware of the risks associated with substance abuse. They can succumb to peer pressure or the desire to experiment, especially if they don’t learn about the negative consequences and effects substance use can have on their present and future lives.

Parents Can Make a Difference


During adolescence, parents and teens are faced with a number of challenges that can seem overwhelming at times. Many of these challenges are associated with the changes taking place in your teen’s brain. Keep in mind that although your teen might sometimes seem mature, they are still subject to the ups and downs associated with the developing adolescent brain.

Even though they may not want to admit it, they still need your support and guidance, especially when it comes to making appropriate and healthy lifestyle choices. Yet it’s not always easy to talk to your child, especially if they seem to want to push you away or appear to disregard your advice.

It’s normal to be concerned about whether your child is abusing tobacco, alcohol, or other substances, such as illicit drugs or prescription medications. Talking to your child and staying involved are 2 of the most effective methods of preventing substance abuse and ensuring your teen’s overall health and wellbeing. Research confirms the crucial role parents play in preventing their children from engaging in substance abuse.9

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