The volume of brain region called the orbitofrontal cortex may predict vulnerability to regular use of cannabis and substance use in general, according to new research published in the Journal of Psychopharmacology.

“The orbitofrontal cortex is important for decision-making and a key structure involved in the addiction cycle,” explained study author Natasha E. Wade, a postdoctoral fellow at the University of California, San Diego.

“We wanted to see if pre-existing characteristics in the orbitofrontal cortex (OFC) structure could predict which adolescents may later start using cannabis and other substances. If so, this could be an important biomarker for prevention efforts. We also wanted to replicate prior findings of OFC and later substance use.”

The researchers used magnetic resonance imaging scans to examine the brain structure of 118 adolescents who had been recruited from San Diego area schools. The participants, who did not report using any illicit drugs at the beginning of the study, then underwent annual assessments of substance use for up to 13 years.

Wade and her colleagues found that participants with larger left lateral OFC volumes were more likely to become regular cannabis users.

“Many different factors lead to later substance use and no one cause is determinative. Still, neurobiological factors are an important piece of the puzzle, and we can hopefully use this information in the future to design prevention efforts to curb problematic substance use in teens,” Wade told PsyPost.

The participants who became cannabis users tended to also have higher levels of alcohol, cigarette, and other drug use. This raises the question of whether orbitofrontal cortex volume may be an indicator of a general vulnerability to substance use.

“We only looked at several structural characteristics of one brain region. There are many other brain regions to study with a range of structural and functional techniques,” Wade said.

“The full clinical implications of the findings still need to be determined. In other words, we need to determine how we can use the neurobiological findings to help people in their day-to-day lives.”

A large, longitudinal study of brain development and child health in the United States could shed more light on the topic.

“The Adolescent Brain Cognitive Development (ABCD) study is designed to learn about adolescent brain health and factors that may influence it, including substance use. Researchers are following around 12,000 9-10 year-olds at 21-sites across the country for 10 years. It will be exciting to see how findings from ABCD expand on the present results,” Wade explained.

The study, “Orbitofrontal cortex volume prospectively predicts cannabis and other substance use onset in adolescents”, was authored by Natasha E. Wade, Kara S. Bagot, Claudia I. Cota, Aryandokht Fotros, Lindsay M. Squeglia, Lindsay R. Meredith and Joanna Jacobus.