Mental Health Spillovers in Primary Schools

Abstract
In this paper we use extensive Danish register data to study peer effects from students with mental health problems. In our analysis, mental health problems are defined from health information in registers on medical prescriptions, contact with general practitioners and psychologist and psychiatrists. We follow classes from 1^st to 6^th grade between 2007 and 2013 and study mental health trajectories of incumbent students when receiving a new student with mental health problems. We use a time to event design, controlling for individual and grade fixed effects and using never treated school-grades as a control. Following the new difference-in-differences literature, we produce estimates that are robust to heterogeneity across cohorts and grades. As additional robustness check, we compare against classes that receive a new student without a mental health problem, and produce results adjusting for changes in diagnoses trends. We find that outcomes for incumbent students are affected by receiving a new student with mental health problems, an effect that is larger when first exposure occurs by grade 6. These effects are long-lasting irrespective of the gender of the mover and of the gender of the incumbent student. The effects are stronger when the mover has a diagnosis of ADHD or autism, suggesting that class distortion could be a potential mechanism.