Peer Mental Disorders Linked to Higher Risk

Introduction

Researchers in Finland conducted a large-scale study to investigate whether having classmates diagnosed with a mental disorder in the 9th grade of comprehensive school is associated with an increased risk of later developing a mental disorder. The study analyzed data from over 700,000 individuals and found a dose-response relationship, meaning that having more than one classmate with a mental disorder diagnosis was linked to a higher risk of receiving a mental disorder diagnosis during the follow-up period, particularly within the first year.

Research Purpose and Motivation

The main goal of this study was to understand the potential social transmission of mental disorders within adolescent peer networks. The researchers wanted to investigate the association between having classmates with mental disorder diagnoses and the later risk of being diagnosed with a mental disorder.

Methodology and Study Design

The study population included individuals with various types of mental disorders, such as substance misuse, schizophrenia spectrum, mood, anxiety, eating, and behavioral and emotional disorders. The researchers used advanced statistical models called mixed-effects Cox proportional hazards regression to estimate the risk, while accounting for demographic, socioeconomic, and intergenerational factors.

Results and Their Significance

The study found that having more than one classmate with a mental disorder diagnosis was associated with a 5% higher risk of later receiving a mental disorder diagnosis. This elevated risk was particularly pronounced during the first year of the follow-up period. Further analysis revealed positive associations for specific disorders, including mood, anxiety, and

, as well as the broader category of

internalizing disorders

Mental health conditions that are characterized by inner-directed negative emotions and behaviors, such as depression, anxiety, and social withdrawal.

 

, even when there was only one diagnosed classmate. The researchers also conducted sensitivity analyses, which generally supported the main findings, including when limiting the exposure to more recent diagnoses and considering school class size.

Main Conclusions and Implications

The findings of this nationwide cohort study suggest that the presence of classmates with mental disorder diagnoses may be a risk factor for the development of mental health problems in adolescents and young adults. This highlights the importance of considering peer influences on mental health during key developmental periods, such as adolescence. The results could inform the development of more effective mental health interventions and policies that take into account the potential social transmission of mental disorders within peer networks.