Indiana University Bloomington

Indiana Prevention Resource Center (IPRC)

Substance Abuse and Brain Awareness

Since March is Substance Abuse and Brain Awareness month, the feature article will focus on the effects of substances on the adolescent brain. While drugs can negatively affect anyone who uses them, it has become increasingly clear that these substances have a more substantial impact on adolescents.

Many factors play a part in brain development. It was once believed that the brain was fully developed when it had reached its full weight. This typically occurs between the ages of 10 and 12 (SBIRT for Adolescents 3, 2014). However, we now understand that the completion of brain growth does not signify the end of brain development. Brain maturation is actually not complete until around age 25 (Winters, 2013). Brain maturation includes the development of areas such as the limbic system and the prefrontal cortex. The limbic system is responsible for processing emotions or social information and experiencing rewards or punishments. The prefrontal cortex develops later in adolescence and controls deliberative thinking, logical reasoning, planning ahead, weighing costs/benefits, and regulating impulses (Winters, 2013). Additionally, the developing brain changes the gray matter, which includes the cell bodies of neurons, nerve fibers from them, and support cells (National Institute of Mental Health, 2011). Essentially, the adolescent brain has a very high volume of gray matter in adolescence, but it must be reduced or “pruned” as the brain matures in order to become more efficient. These changes, along with many others, must happen in order for the brain to reach full maturity.

These physiological differences mean that alcohol and other drugs affect the adolescent brain differently than the adult brain. Differences are both short term (affecting the way an adolescent experiences the immediate effect of a drug) and long term (increasing the risk of permanent changes to the brain). For example, research has indicated that adolescent brains are likely to be less sensitive to the sedative effects of intoxication, meaning they will be able to drink more before their brain and body will react to the alcohol (Winters, 2013). Sedation is one of the ways that the brain reacts to alcohol. By making the drinker sleepy, the brain attempts to protect him or her from dangerous levels of alcohol intake (Johns Hopkins School of Public Health). This could be a factor in the high incidence of binge drinking, drinking large quantities of alcohol in a short period of time, that are associated with high school and college aged drinkers. Adolescent brains are also more likely to feel a greater comfort in social situations as a result of alcohol use. This may be another reason why adolescent drinking is so common. Additionally, cognitive impairments might be more likely when alcohol use occurs while the brain is still developing. These impairments can include a disruption in memory, retention, or learning and a decrease in brain activity (Winters, 2013).

Alcohol is not the only substance that has an impact on the adolescent brain. Cocaine and amphetamines specifically target dopamine receptors in the brain. If these neurons are damaged, the adolescent may have difficulties with impulse control and may lack the ability to experience reward (Johns Hopkins School of Public Health). Other substance use can affect judgment, planning or completing tasks, and meeting goals. They can also result in overblown or immature emotional responses to certain situations (Johns Hopkins School of Public Health).

Nicotine is another substance that affects adolescents in a more intense way than with adults. Even though nicotine use usually results in cell damage or loss in users of any age, the effect is greater in adolescents. The hippocampus becomes more damaged, resulting in memory problems. Additionally, more episodes of depression can occur with adolescent smokers (Johns Hopkins School of Public Health).

The developing brain is especially vulnerable to the habit-forming effects of alcohol and other substances. People who begin using alcohol or marijuana after age 21 are much less likely to develop problems with abuse or dependence (Winters, 2013). Adolescents who begin drinking before age 15 are four times more likely to develop a dependence to alcohol than those who wait until age 21 (Johns Hopkins School of Public Health).  Because of this and the other harmful effects of substances on the developing brain, it is essential to reduce or eliminate alcohol use in those under the age of 21 and to eliminate substance use for those under the age of 25. While the goal of substance prevention efforts is to completely eliminate the use of these substances (or to only consume alcohol in moderation once an individual is 21 years of age), more focus must be placed on adolescents. If education and other forms of interventions can help reduce or eliminate adolescent substance use, the number of dependent adults will be reduced, and the negative and potentially long-term consequences on the adolescent brain could be eliminated.

Even though substance use of any kind can have harmful effects on the brain at any age, substance use in adolescence is particularly damaging because the brain is not fully developed. We each must do our part to dissuade children, teenagers, and young adults from using alcohol or other drugs because of the potentially serious problems resulting from it. Simply explaining what can happen to a teenager contemplating drug use could help prevent him or her from partaking in risky behaviors. Encouraging adolescents to resist peer pressure is also important. One conversation could change a person’s entire perspective.

*[For more resources on the topics covered in this article, see the IPRC HOME library e-Resources accessible from IPRC homepage or at].

By Heather Dolne 3/4/2015