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Mental health disorders can spread through young people's social networks
Last reviewed: 02.07.2025
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Researchers from the University of Helsinki, the Finnish Institute for Health and Welfare, the University of Jyväskylä and the University of Manchester used data from population-based registers to examine the transmission of mental disorders within social networks formed by school classes.
The study, published in JAMA Psychiatry, is the largest and most comprehensive to date examining the spread of mental disorders on social media. It involved more than 700,000 ninth-grade students from 860 Finnish schools, who were followed from the end of ninth grade for an average of 11 years.
Researchers have shown that the number of classmates diagnosed with mental disorders is associated with a higher risk of receiving a mental disorder diagnosis later in life.
"The observed association was strongest in the first year of observation. This was not explained by factors related to parents, school and neighbourhood. The association was strongest for mood disorders, anxiety disorders and eating disorders," says Associate Professor Kristian Hakulinen from the University of Helsinki.
Study made possible by extensive Finnish registries Previous studies have found similar results, Hakulinen said: American researchers, for example, have seen signs of potential transmission of depressive symptoms on social media.
However, in previous studies, social networks were usually chosen by the subjects themselves, which could lead to data distortions. Hakulinen points out that school classrooms are suitable social networks for research, since people usually cannot choose their classmates.
"Defining social networks and monitoring adolescents was made possible by the extensive Finnish registers. The data obtained significantly deepens our understanding of how mental health problems develop and how they affect others in our social networks," he says.
Hakulinen, however, notes that the association observed in the study is not necessarily causal. Moreover, the study did not look at how exactly mental disorders might be transmitted between people.
"It is possible that the threshold for seeking help for mental health issues is lowered when you have one or more people in your social network who have already sought help. In fact, such normalization of diagnosis and treatment may be considered a beneficial spread of mental disorders," says Hakulinen.
More prevention? Mental disorders are a significant global problem that negatively impacts individuals, society and the economy. According to Hakulinen, symptoms of anxiety and depression have increased especially among young people in recent years.
Previous studies have shown that in about half of all cases, the onset of mental disorders in adulthood occurs before people turn 18. Hakulinen emphasizes the importance of prevention and early intervention.
"When carrying out preventive measures, it is worth considering that mental disorders can spread from one teenager to another," says Hakulinen.
The study included a total of 713,809 Finnish citizens born between 1985 and 1997. The adolescents were followed from the end of school until they were first diagnosed with a mental disorder, left the country, or died. The follow-up ended no later than the end of 2019, resulting in an average follow-up period of 11.4 years.