How Substance Abuse Impacts the Adolescent Brain

Boy dealing with loneliness and isolation during the COVID-19 pandemic

Adolescence is a distinctive and crucial period in the process of neurodevelopment. Undergoing such a profound yet challenging development exposes the adolescent to greater risks of errors in judgment.

Hence, it comes as no surprise that teenagers are more prone to substance abuse than any other age group and are much more vulnerable to neurological damage due to psychoactive substances. Recent research has highlighted significant abnormalities in the brain functioning due to alcohol and drug use during adolescence.

Almost 50 percent of high school seniors have reportedly abused a drug of some kind and over 30 percent of young adolescents have tried alcohol by the time they reached the 8th grade. Furthermore, almost 7 percent of high school seniors smoke cigarettes every day.[1]

Adolescent Brain Development

Adolescence is characterized by rapid social, biological and psychological variations. Such multidimensional elements are a profound influence on the brain development.

The human brain is shaped by experience. The brain of a newborn consists of a lot more neural connections, essentially unspecialized and undeveloped. Gradually, certain connections are strengthened (for example the nerves that process the sight of parents’ faces or their voices) and others are pruned, or trimmed, away.

This processing and pruning of nerves initiated from infancy, continues throughout adolescence, and even into initial adulthood.

The most prominent development in adolescence constitutes that of the brain’s frontal lobe and outer mantle. The prefrontal cortex, situated in the frontal lobe, entails important skills such as determining priorities, strategizing, apportioning attention and managing impulses. The outer mantle includes processing intellectual information and understanding rules, laws and dynamics of social interaction.

The occurring behaviors associated with these developments are obvious. Young adolescents are infamous for their compulsive fixation with socialization including the making and breaking of social rules. As teenagers transition into the early stages of adulthood, they typically demonstrate a profound intellectual interest in topics like history, culture and media, depicting their widening ability to comprehend the wider world.

Yet, the development of fully matured complex thinking requires more time. MRI studies have shown the development of the prefrontal cortex and outer mantle of the brain to continue into the early 20s, with a chance of not even being completed until the mid 20s.

Adolescent Girl Sitting With Her Head In Her Hands struggling with Substance Abuse

As the logical thought process is initiated increasingly over time, the connections become stronger, and as the process nears its conclusion, some areas of nerves are enveloped in a fatty layer called a “myelin sheath.” Similar to insulation on a wire, this fatty layer enables the nerve connections to process faster, making rational, reasoned decisions more quickly and more efficiently. [2]

Adolescent Substance Abuse and the Brain Structure

Hippocampal Volume. Hippocampus is an area of the brain that is responsible for memory functioning. Findings from a study comparing non-drinkers and heavy drinkers demonstrated that heavy alcohol use in adolescence negatively impacted memory performance. Alternatively, heavy adolescent marijuana use may result in subtle interferences with synaptic pruning processes, resulting in larger gray matter volumes.

Prefrontal Cortex Volume. During adolescence, the frontal lobe, an area of the brain associated with planning, inhibition and emotion regulation goes through extensive maturing process, increasing in efficiency and specialization. In a study comparing prefrontal cortex volumes of adolescent heavy drinkers to non-drinkers and marijuana and alcohol users, prefrontal volumes were found to be smaller in heavy drinkers.

White Matter Volume. White matter maturation during adolescence through young adulthood is important for transmission of neurons between the brain regions. It seems plausible that marijuana use may cause or be linked to subtle alterations in white matter tracts that are responsible for mood regulation and depressive symptoms. Excessive alcohol use is also suggested to be associated with tissue scarring.

Brain Blood Flow. Cerebral blood flow (CBF) is important since inadequate blood flow can damage brain tissue. Chronic alcoholics have been shown to have reduced blood flow into the brain. These findings may help clarify the metabolic changes behind differences in functional brain activity seen in adolescents with histories of alcohol misuse. [1]

Adolescent Substance Abuse and the Brain Function

Alterations in brain structure can lead to constrained brain functioning associated with adolescent substance use. Research has shown that substance abuse during adolescence can result in decreased performance on cognitive tasks of memory, attention, spatial skills and executive functioning. Such consequences may be associated with the structural changes discussed above.

Spatial Working Memory. Studies found that adolescents who engaged in heavy drinking demonstrated cognitive abnormalities regarding spatial working memory in contrast to light drinkers. Additionally, youth with greater alcohol consumption showed greater abnormalities and restricted brain ability to compensate for alcohol-related deficiencies in neural functioning.

Verbal Encoding. Diminishing verbal encoding abilities have also been observed in binge drinking adolescents during MRI studies involving exercises of recalling learned words. The results suggested slightly poorer initial verbal learning, disadvantaged verbal processing, and decelerated learning for adolescents who engage in binge drinking compared to abstinent adolescents.

Inhibition. Significantly reduced ability to inhibit behaviors has been prominent in binge drinking adolescents and those abusing hard drugs. Even if infrequent, exposure to large doses of alcohol may influence inhibitory processing. [1]

Prevention and Treatment

Three Brothers Standing By A LakeEven though substance abuse can lead to addiction irrespective of age, research illustrates that sooner a person initiates use of drugs, greater the likelihood of dependence. Around 7 percent of youth who initiate drinking around 12 years of age end up with an alcohol use disorder within two years compared to those who waited until age 21 to engage in heavy drinking. The prevalence of alcohol abuse within two years for this population was 3.7 percent.

Hence, it is essential to employ comprehensive, effective and accessible educational tools and awareness programs to dissuade young adolescents from substance abuse. Not only does the necessity of prevention and treatment needs to be reinforced but adjusted to teach youth about its repercussions for their brain development.

It is also vital for parents to frequently and thoughtfully communicate with their teenager about the ramifications of drugs and alcohol. Research suggests that having this conversation with parents reduces the chance of their child abusing psychotropic substances by 42 percent. Yet, only 25 percent of teens reported having these conversations.[3]

Sana Ahmed photoAbout the Author:

A journalist and social media savvy content writer with wide research, print and on-air interview skills, Sana Ahmed has previously worked as staff writer for a renowned rehabilitation institute focusing on mental health and addiction recovery, a content writer for a marketing agency, an editor for a business magazine and been an on-air news broadcaster.

Sana graduated with a Bachelors in Economics and Management from London School of Economics and began a career of research and writing right after. The art of using words to educate, stir emotions, create change and provoke action is at the core of her career, as she strives to develop content and deliver news that matters.



The opinions and views of our guest contributors are shared to provide a broad perspective of addictions. These are not necessarily the views of Addiction Hope, but an effort to offer discussion of various issues by different concerned individuals.

We at Addiction Hope understand that addictions result from a combination of environmental and genetic factors. If you or a loved one are suffering from an addiction, please know that there is hope for you, and seek immediate professional help.

Published on June 11, 2017.
Reviewed By: Jacquelyn Ekern, MS, LPC on May 26, 2017
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About Baxter Ekern

Baxter Ekern is the Vice President of Ekern Enterprises, Inc. He contributed and helped write a major portion of Addiction Hope and is responsible for the operations of the website.