Sep 19, 2024 08:00:00

Research shows that the genes of friends from school days affect future health

There are many studies showing how the environment in childhood has a large impact on later life, such as

research showing that the negative effects of bullying experienced as a child continue even into adulthood. Furthermore, a paper was published in the American Journal of Psychiatry, a peer-reviewed medical journal published by the American Psychiatric Association, stating that not only the genes of parents and one's own, but also the genes of classmates at school are related to the risk of health problems such as mental illness.

Peer Social Genetic Effects and the Etiology of Substance Use Disorders, Major Depression, and Anxiety Disorder in a Swedish National Sample | American Journal of Psychiatry
https://psychiatryonline.org/doi/10.1176/appi.ajp.20230358

Your Old School Friends' Genes Could Be Impacting Your Health, Study Finds : ScienceAlert
https://www.sciencealert.com/your-old-school-friends-genes-could-be-impacting-your-health-study-finds

To investigate the effect of friends' genotypes on health, or the 'social genetic influence of friends,' a research team led by Jessica E. Salvatore, a psychiatrist at Rutgers University in the United States, analyzed data from a Swedish survey containing approximately 650,000 medical records of individuals aged 17 to 30.

The analysis first mapped each individual's risk of substance abuse and psychiatric disorders, then calculated a 'family genetic risk score' that indicated the likelihood that addiction or mood disorders are rooted in genetic characteristics.

The research team also matched the data with information about region and school attended to explore relationships between genetic risk scores and the tendency of school peers and community members to experience similar outcomes.

They found that people who dated people who had a high genetic risk for various health problems were more likely to develop those same problems, even if they didn't have the same risks in their own genes.

'Peer genetic predisposition to mental illness and substance use disorders was associated with an individual's risk of developing the same disorders in early adulthood,' Salvatore said. 'These data illustrate the pervasiveness of social genetic influences.'

This new field of research, called sociogenomics, studies how one person's genotype manifests itself in others, and while there is some evidence that this does affect people in this way, it's not clear why this is the case.

Salvatore and his team focused on issues such as drug use disorders, alcohol use disorders, major depression, and anxiety disorders. The likelihood that these health problems are influenced by past peers varies, but the effect on substance use disorders is particularly pronounced, with risk increasing by up to 59% among groups of friends who attended the same high school.

The effects are not limited to schools, but also include small but significant effects observed among residents of the same neighborhood, most pronounced among those aged 16-19, but also associated with health problems in adulthood.

Interestingly, the influence of friends' genes was present even if the friends did not have a particular health problem: for example, people who went to school with classmates who were genetically at high risk of developing alcohol problems were more likely to suffer from alcohol problems later in life, even if those classmates did not have alcohol problems.

'Our analysis shows that peer genetic predisposition is associated with a subject's risk of the disorder, even after statistically controlling for whether peers are affected,' Salvatore said.

While it's natural for people to be influenced by the behavior of their peers at school, this study's look at genetic links, suggesting that there are deeper biological mechanisms at work.

The research team plans to conduct further investigations to apply these findings to improve the diagnosis and treatment of health problems, including mental illness.