Remember your mom telling you to choose your friends wisely?
It turns out she was right, but in ways we’re only beginning to understand.
A new study led by a Rutgers Health professor has found that the genetic makeup of your high school friends could have a long-term impact on your mental health and risk of substance abuse.
The study, published in the American Journal of Psychiatry, was led by Jessica E. Salvatore, an associate professor of psychiatry at the Rutgers Robert Wood Johnson Medical School.
The research suggests that the genes of the people you spend time with during adolescence can influence your own risk of developing disorders like depression, anxiety, and drug or alcohol addiction in adulthood.
This study is part of a growing field called socio-genomics, which looks at how one person’s genes can affect another person’s traits. To explore this, Salvatore and her colleagues used data from more than 1.5 million people born in Sweden between 1980 and 1998.
They mapped out where these individuals lived and went to school during their teenage years and then analyzed medical records to see who later developed mental health or substance abuse issues.
The researchers focused on something called “social genetic effects,” which is the idea that your friends’ genetic predispositions can influence your own health outcomes.
For example, if your friends have a genetic tendency toward alcohol or drug abuse, it could increase your own risk of developing similar issues, even if you don’t share those same genetic risks.
To test this, the team looked at family genetic risk scores, which are personalized measures of genetic risk based on family history.
They found that even when they controlled for factors like a person’s own genetic predispositions and family background, there was still a strong connection between the genetic tendencies of peers and the likelihood of developing substance abuse or mental health disorders later in life.
Interestingly, these effects were stronger among friends from school than among friends who just lived in the same neighborhood.
The most significant influence was seen in high school classmates, especially those in the same vocational or college-preparatory programs between the ages of 16 and 19.
The study found that these social genetic effects were more pronounced for drug and alcohol use disorders than for depression and anxiety.
Salvatore emphasized that more research is needed to understand exactly why these connections exist. One possible explanation is that a friend’s genetic predispositions might influence their behavior, which then affects you.
However, the study found that even after accounting for whether friends actually developed these disorders, the influence of their genetic predispositions remained.
The findings suggest that if we want to tackle mental health and substance abuse issues effectively, we need to consider social networks and group-based interventions, not just individual risk factors.
Salvatore pointed out that these peer influences can last for a decade or more after high school, highlighting the long reach of our social connections.
This research, which also involved experts from Sweden’s Lund University and Virginia Commonwealth University, shows just how much our social environment—and the genes of those in it—can shape our future health.
If you care about mental health, please read studies about 6 foods you can eat to improve mental health, and B vitamins could help prevent depression and anxiety.
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