How Brain Structure Affects Early Substance Use in Teens

A recent study funded by the National Institutes of Health (NIH) has identified structural brain differences in adolescents who begin using substances before the age of 15. These differences, observed through MRI scans, could play a key role in the early initiation of substance use and potentially in the development of substance use disorders. The study used data from the Adolescent Brain Cognitive Development Study (ABCD Study), the largest longitudinal research project on brain development in children and adolescents across the U.S.

The study analyzed MRI scans of nearly 10,000 adolescents and followed them over three years. The researchers compared the brain structure of 3,460 adolescents who initiated alcohol, nicotine, or cannabis use before age 15 with 6,344 peers who had not started using substances. The analysis revealed five global brain structural differences between the two groups, including larger brain volumes and greater subcortical volumes in those who initiated substance use earlier.

In addition to these global differences, 39 regional differences were observed, particularly in the cortex, the outer layer of the brain responsible for cognitive functions such as learning, memory, and decision-making. These structural differences were found to be associated with impulsivity and sensation-seeking behaviors, traits often linked to higher substance use risk.

The findings suggest that some of these brain structural differences may exist even before adolescents begin using substances, pointing to the possibility that these differences are biologically embedded and may influence susceptibility to substance use later in life. The study emphasizes that the interaction between genetic factors, brain structure, and environmental influences—such as exposure to pollution—plays a crucial role in shaping adolescent behavior and risk for addiction.

As highlighted by Alex Miller, Ph.D., the study’s corresponding author, this research contributes to a deeper understanding of how brain structure and substance use are linked. Future studies will be crucial in exploring how these brain differences evolve and how they may influence long-term substance use patterns and the risk of substance use disorder.

More Information: Miller, A. P., et al. (2024). Neuroanatomical Variability and Substance Use Initiation in Late Childhood and Early Adolescence. JAMA Network Open. doi.org/10.1001/jamanetworkopen.2024.52027.