A recent study conducted in Finland involving over 700,000 individuals has raised the possibility that mental illnesses such as depression, anxiety, and eating disorders could be socially transmitted within adolescent peer groups. Published in JAMA Psychiatry in May 2024, the study found that individuals who had peers diagnosed with a mental disorder during adolescence had an increased risk of receiving a mental disorder diagnosis later in life. The risk was particularly high when multiple diagnosed individuals were in the peer network, with the greatest risk observed for mood, anxiety, and eating disorders.
The researchers hypothesized several mechanisms through which mental disorders might be transmitted socially. These mechanisms include the normalization of mental disorders, peer social influence, and emotional contagion, where individuals unconsciously mimic the emotions and behaviors of those they spend time with. Lead author Jussi Alho and colleagues analyzed data from Finnish citizens born between 1985 and 1997, conducting follow-ups with participants after completing ninth grade to track mental disorder diagnoses until 2019.
The study found that having classmates diagnosed with mood, anxiety, behavioral, or eating disorders was associated with a higher risk of later diagnosis, with the risk being highest during the first year of follow-up. For example, having classmates with a mood disorder diagnosis was linked to a 32% higher risk of being diagnosed with a mood disorder in the first year. These findings align with previous research on clustering of mood and anxiety symptoms in social networks and suggest a potential social transmission of mental disorders among adolescents and adults.
Overall, the study sheds light on the complex interplay between social relationships and mental health outcomes, emphasizing the importance of understanding how mental illnesses can be influenced by peer groups. Further research in this area could help inform interventions and support strategies to address mental health issues within communities.