Finnish study links teen mental health diagnoses to peer groups

A nationwide Finnish study has found that adolescents were more likely to be diagnosed with a mental health condition when their peers had the same diagnosis or a family history of it. The findings matter because they add evidence that schools and peer groups may shape teen mental health risk, while leaving open how much comes from friendship, shared environments or other factors.

The study, published in JAMA Psychiatry, analyzed records for more than 600,000 people in Finland born from 1985 through 2000. The researchers used national health and school enrollment data to compare young people’s later mental health diagnoses with diagnoses among people in their peer networks.

According to the researchers, adolescents had a higher chance of receiving a diagnosis for a condition such as anxiety or depression if peers had already been diagnosed with the same condition. They also found a link when peers had family members with diagnosed mental health conditions.

The association was stronger for young people who attended the same school than for those who lived in the same area, the researchers reported. The school-based link was especially clear in later adolescence.

What “peer transmission” means

The study authors said the results support the idea that mental health risk can be socially transmitted among adolescents. Researchers writing in The Conversation cautioned that the term does not mean mental illness spreads like an infection.

In this context, transmission refers to the way emotions, behaviors, norms and help-seeking patterns can move through social groups over time, according to the researchers. A peer group with more openness about mental health, for example, could make young people more willing to seek care, though the Finnish study did not test that explanation.

The findings arrive as youth mental health problems have increased in several countries. The Conversation authors cited Australian data showing anxiety among young people rose from 13% to 28% over 15 years, while suicide attempts doubled.

Limits of the findings

The study’s scale is a major strength, but its methods also limit what it can show. Because the researchers used register data, they could define peers by school year, grade cohort or location, but could not know whether those young people were friends or even knew one another.

The researchers also inferred genetic risk from family diagnoses rather than DNA. That measure may miss people with mental health conditions who were not diagnosed, and it cannot capture every family or social factor that could affect risk.

The study accounted for some background factors, including sex, age and parents’ income and education, according to The Conversation authors. It did not include other influences linked to adolescent mental health, such as gender identity, ethnicity, school characteristics, smoking, alcohol use or exercise.

Shared environments may also explain part of the connection. Students in the same school or community can experience similar school cultures, teaching approaches, neighborhood conditions and access to green space, the researchers noted.

Implications for schools

The findings do not prove that friends cause one another’s mental health conditions. The Conversation authors said more research is needed to separate peer selection, in which young people choose similar friends, from peer influence, in which friends shape one another over time.

Even with those limits, the study points to schools as a key setting for prevention. The Conversation authors cited school-based programs that use peer support, including Australia’s Mind your Mate program, which has shown promise in lowering depression risk among teenagers.

The broader conclusion, according to the researchers, is that adolescent mental health cannot be understood only at the individual level. Schools, families, peer groups and communities all form part of the setting in which mental health risks develop.

This story draws on original reporting from Phys.org.