In a surprising reversal of conventional wisdom, new research suggests that certain brain features may predispose adolescents to try substances early in life, rather than brain differences being caused by substance use itself.
Washington University researchers analyzed brain scans from nearly 10,000 children, uncovering structural differences that existed before any substance exposure. The study, published in JAMA Network Open, compared participants who tried substances before age 15 with those who didn’t.
“What we looked at was whether these neural differences precede any substance involvement essentially. And we do find that,” explains Ryan Bogdan, dean’s distinguished professor of psychological & brain sciences at Washington University and study co-author.
The research team identified variations in cortical structure, particularly in the prefrontal cortex, among approximately 3,500 participants who reported early substance experimentation compared to their peers. These differences remained significant even after controlling for family history and prenatal substance exposure.
Study co-author Arpana Agrawal, the James and Juanita Wittmer Professor in psychiatry at WashU Medicine, cautions against viewing these findings as a diagnostic tool. Instead, she sees them as one piece of a complex puzzle: “I think this is a clue that we need to think about the relationship between substance use and brain development somewhat differently.”
Most early substance encounters reported in the study were minor, typically involving small amounts of common substances like alcohol. The research team, including lead author Alex Miller, now at Indiana University School of Medicine, used sophisticated statistical methods to account for various factors that might influence results.
The findings challenge previous assumptions that early substance use primarily causes brain changes. Miller, who studies how impulsivity relates to these brain structures, notes that “the patterns of associations that we’re seeing are of interest” compared to earlier research.
This study marks an important shift in understanding substance use risk factors, suggesting that certain brain characteristics might influence behavior before any substance exposure occurs. Future research will focus on unraveling the complex relationship between brain structure, development, and substance use patterns.