BONN, GERMANY – JANUARY 17: In this photo a man, depressed, sits alone on a … [+]
A new study of more than 700,000 people living in Finland found that mental illnesses such as depression, anxiety and eating disorders could potentially be socially transmitted within teenage peer groups.
“We found an association between peers diagnosed with a mental disorder during adolescence and an increased risk of being diagnosed with a mental disorder later in life,” the researchers wrote. JAMA Psychiatry study published May 22, 2024. “There was a higher risk when many diagnosed individuals were in the peer network. Of the mental disorders examined, the risk was greatest for mood, anxiety and eating disorders.”
The team hypothesized that various mechanisms could be involved if mental disorders were socially transmitted through peer groups. “One plausible mechanism is the normalization of mental disorders through increased awareness and receptivity to diagnosis and treatment when there are diagnosed individuals in the same peer network,” the authors explained.
For eating disorders, they noted that transmission may occur due to “peer social influence processes to which adolescents are particularly sensitive.”
“It is (also) conceivable that long-term exposure to a depressed individual could lead to the gradual development of depressive symptoms through well-established neural mechanisms of emotional transmission,” the authors add. Social psychologist Elaine Hatfield coined the term “emotional contagion” to describe how people observe and then unconsciously imitate the emotions and behaviors of the people they spend most of their time with.
Lead author Jussi Alho from the University of Helsinki and colleagues analyzed data on 713,809 Finnish citizens born between 1985 and 1997 collected from national registers. The team followed up with the study participants immediately after completing the ninth grade at age 16 in 860 schools across Finland. During each follow-up, they checked whether they had been diagnosed with mental disorders or not and continued to do so until December 31, 2019.
Of the 713,809 study participants, 47,433 had been diagnosed with a mental disorder by ninth grade. Another 25% or 167,227 people received a diagnosis of a mental disorder during the follow-up period.
Through their data analysis, the researchers found that having more than one classmate with a mood, anxiety, behavior or eating disorder was associated with a 5% higher risk of later diagnosis. “During the first year of follow-up, the risk of diagnosis was 9% higher with one diagnosed classmate and 18% higher with more than one diagnosed classmate,” the authors noted. “Diagnosis-specific analyzes showed that risk was significantly elevated for mood, anxiety, and internalizing disorders at each follow-up time window, with the greatest risks observed during the first year.”
“For example, having classmates diagnosed with a mood disorder was associated with a 32% higher risk of being diagnosed with a mood disorder during the first year of follow-up,” they added. “Our findings are consistent with previous studies reporting clustering of mood and/or anxiety symptoms in adolescent and adult social networks, as well as evidence suggesting similar social transmission of eating disorders,” they added.
