By Amber Roman
Aug 11, 2024, 12:00 PM EDT
A groundbreaking study by a research team led by Jessica E. Salvatore, associate professor of psychiatry at Rutgers Robert Wood Johnson Medical School, has shown that the genetic traits of friends during adolescence can significantly affect mental health and the risk of developing addictions in early adulthood.
This finding, published in the American Journal of Psychiatry, sheds new light on the influence of social genetics on people’s lives.
The research focuses on sociogenomics, an emerging field that studies how one person’s genotype can influence another person’s observable traits. This study used an anonymous database of more than 1.5 million people born in Sweden between 1980 and 1998, whose parents were also born in Sweden. Salvatore’s team mapped the individuals by their location and school during adolescence, and then tracked their medical, pharmaceutical and legal records into adulthood to identify mental health disorders and substance abuse problems.
Researchers tested whether peer genetic predispositions in adolescence predict an individual’s likelihood of developing problems such as substance abuse, depression, and anxiety in adulthood. What they found was revealing: Even when controlling for factors such as individual genetic predispositions and socioeconomic factors, there was a clear association between peer genetics and risk for psychiatric or substance use disorders. These effects were more pronounced among school peers than among geographically defined peers.
Within the school setting, the strongest effects were seen among upper secondary school students, particularly those pursuing vocational courses or preparing for university between the ages of 16 and 19. The social genetic influence was greater for drug and alcohol use, compared with depression and anxiety.
The study also offers clues about the need to rethink mental health interventions. Salvatore suggests that strategies need to go beyond focusing on the individual and address problems from a social network perspective. “It is not enough to think about individual risk,” he said. This suggests that to effectively address socially costly disorders, it is critical to consider social and genetic dynamics within groups.
Furthermore, the research underscores the importance of interrupting risk processes that extend far beyond adolescence. According to Salvatore, genetic influences from friends can have a long-term impact, and this knowledge should inform mental health policies and programs.
However, questions remain. Salvatore acknowledges that further research is needed to fully understand why friends’ genetic predispositions are so strongly associated with mental health disorders in their peers’ lives. One possible explanation is that these predispositions directly influence friends’ observable behavior, which in turn affects those around them. However, the data suggest that peers’ genetic influence may operate independently of whether or not they develop the disorder.
This study, which involves the collaboration of experts from Lund University in Sweden and the Virginia Institute for Psychiatric and Behavioral Genetics, provides new insight into how our social relationships and the genetics intertwined with them shape our mental health. While more research is needed, the findings highlight the importance of considering both social and genetic environments in the prevention and treatment of psychiatric and addiction disorders.
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