Teens may be able to pass on mental disorders to each other, a new study has found.
According to a new paper in the journal JAMA Psychiatry, ninth-grade students with school friends with a mental disorder were more likely to develop one themselves later on in life.
This association was still present even when parental factors and their addresses were considered.
"The findings of this study suggest that mental disorders might be transmitted within adolescent peer networks," researchers at the University of Helsinki in Finland wrote in the paper.
Read more: Compare Top Health Savings Accounts
Research previously found that mental disorders may extend to family members and even to friends within social networks. The researchers in Finland examined data on more than 710,000 Finnish people from across 860 high schools to determine if having a friend with a mental disorder affected a person's likelihood of developing one.
About 47,000 of the group had been diagnosed with a mental disorder of some kind by ninth grade, with a further 167,000—25 percent of the total—being diagnosed during a follow-up later in life.
The researchers found that there was a 5 percent increase in total risk of being diagnosed with a mental disorder if a person had more than one diagnosed classmate, but no increased risk for a single diagnosed classmate. The association was particularly strong in the first year of follow-up, with a 9 percent increased risk if a person had one diagnosed classmate, and an 18 percent increased risk if they had more than one diagnosed classmate.
The risks were highest for mood disorders, anxiety disorders and eating disorders.
"We found an association between having peers diagnosed with a mental disorder during adolescence and an increased risk of receiving a mental disorder diagnosis later in life," the researchers wrote. "This risk was most pronounced in the first year of follow-up. The association showed a dose-response relationship, with higher risk when multiple diagnosed individuals were in the peer network."
According to Michaela James, a mental health researcher at Swansea University in the U.K., there's an increasing trend of poor health and well-being in young people.
"In particular, mental health issues, including emotional and behavioral difficulties, have increased, with emotional difficulties affecting 13-15 percent of children in 2017-2018 and impacting 29 percent of children in 2021-2022. Moreover, indicators of well-being, autonomy and competence have declined. As well as this, the findings reveal a decline in physical health between 2014 and 2022, as evidenced by reduced abilities in swimming and cycling. Additionally, unhealthy eating habits, such as decreased fruit and vegetable consumption and increased consumption of sugary snacks, have become more prevalent," she told Newsweek.
"I would argue that a rise in mental health diagnosis is not simply because 'your friend was diagnosed' or you are exposed to mental health disorders. I believe this is a wider societal and cultural issue, not one that should be individualized," she added.
In the paper, the researchers suggest several mechanisms for how these mental disorders may be transmitted in peer networks, one of which is the normalization of mental disorders, where increased mental health awareness and receptivity to diagnosis could occur when individuals with diagnoses are present in a social network.
Having peers without diagnoses might discourage seeking help for underlying mental health issues, on the other hand. The higher risk of diagnosis observed in the first year after exposure works with this theory, as the brief latency seen between exposure and diagnosis indicates pre-existing, undiagnosed disorders rather than a harmful contagion.
Another possible mechanism, especially for disorders like depression, is direct interpersonal contagion. For some disorders, like eating disorders, transmission may occur through peer social influence, which teenagers are particularly at risk of.
"We are currently living through many cultural, societal and economic upheavals. Therefore, it is imperative to prioritize the development and implementation of effective and sustainable interventions, funding distribution and policy focus that address physical skills like swimming and cycling, opportunities that promote confidence and autonomy in physical activity, and enhance overall well-being and socialization. It is also essential to recognize that the pandemic and its accompanying restrictions could exacerbate these issues," James suggested. "Individualizing mental health in this way is problematic. There are many factors that are at play here, particularly in our contemporary landscape."
Researchers still aren't clear on what drives this association and hope to further investigate how and why mental disorders may spread in social networks.
"Prevention and intervention measures that consider potential peer influences on early life mental health could substantially reduce the disease burden of mental disorders in society," they wrote. "Further research is required to clarify the mechanisms that explain these observed associations."
Do you have a tip on a science story that Newsweek should be covering? Do you have a question about mental disorders? Let us know via science@newsweek.com.
About the writer
Jess Thomson is a Newsweek Science Reporter based in London UK. Her focus is reporting on science, technology and healthcare. ... Read more
