A study led by the Psychiatry, Mental Health and Addictions group at the Vall d’Hebron Research Institute (VHIR) has identified a set of genetic factors that simultaneously influence the risk of developing an addictive disorder and the level of educational attainment. The results, published in the journal Addiction, indicate that some genetic variants act in opposite directions: a higher genetic predisposition to addiction is associated with a greater likelihood of achieving a lower educational level. The work was carried out in collaboration with the Mental Health Area of the Biomedical Research Networking Centre (CIBERSAM), the Rare Diseases Area of the Biomedical Research Networking Centre (CIBERER), the Sant Joan de Déu Research Institute (IRSJD), the University of Barcelona (UB), the Autonomous University of Barcelona (UAB) and the University of California, San Diego (UCSD).

This relationship had been repeatedly observed in different studies, but until now there was a lack of solid genetic evidence explaining their overlap. “We have known for decades that school difficulties and substance-use problems often appear together and can reinforce each other. Our work provides new genetic data that help clarify this association,” explains Dr. Judit Cabana-Domínguez, principal investigator of the Psychiatry, Mental Health and Addictions group at VHIR and CIBERSAM.

To carry out the research, the team recruited more than 1,400 people diagnosed with substance use disorders, including cocaine, opioids, cannabis and sedatives. Using these data, they applied a genome-wide association study (GWAS) to identify genetic variants that influence both addiction risk and educational attainment.

The results made it possible to detect a set of genetic variants that increase the risk of addiction and are simultaneously associated with a lower educational level. These variants not only play a relevant role in the development of substance use disorders but have also been linked to poorer health and more disadvantaged socioeconomic conditions.

A shared link that does not define the direction of influence

Despite the genetic overlap identified, the study does not resolve the direction of influence between addiction and educational attainment. “Although we found consistent evidence of shared variants, our work cannot determine whether a lower educational level increases the risk of addiction, whether it is addiction that hinders educational progress, or whether both are true,” warns Dr. Marta Ribasés, principal investigator of the Psychiatry, Mental Health and Addictions group at VHIR and CIBERSAM.

According to the researcher, these results open the door to deeper exploration of the biological and environmental mechanisms that connect learning, cognitive development and addictive disorders. “There is still a lot of work ahead, but gaining a better understanding of shared genetic factors may help improve prevention strategies and integrate an educational perspective into public health policies on addictions.”