Physical exercise and risk of common mental disorders among higher education students: A national prospective study

BACKGROUND: Physical exercise is associated with better mental health and lower psychological distress, yet few studies have examined its relationship with diagnostically defined common mental disorders (CMD) in young adults. This study investigated prospective associations between multiple dimensions of physical exercise and subsequent CMD among students in higher education. METHODS: Data were drawn from the Students' Health and Wellbeing Study (SHOT2022), a national survey of Norwegian higher education students (n = 53,362; age 18-35 years). Physical exercise frequency, intensity, duration, and total weekly hours were assessed at baseline. CMD, defined as major depressive episode (MDE) or generalized anxiety disorder (GAD) during the past 30 days or 12 months, was assessed one year later using the self-administered Composite International Diagnostic Interview (CIDI 5.0) (n = 10,460). Associations between exercise indicators and CMD were examined using inverse probability weighted Poisson regression models, yielding risk ratios (RR) and 95% confidence intervals (CI), stratified by sex and examined across two age groups (18-24 and 25-35 years), and sequentially adjusted for sociodemographic variables and baseline psychological distress (HSCL-25). RESULTS: Lower levels of physical exercise were consistently associated with higher relative risk of subsequent CMD. Compared with daily exercisers, those who seldom or never exercised had higher adjusted RR of CMD (women: RR = 1.15, 95% CI 1.04-1.28; men: RR = 1.33, 95% CI 1.06-1.65). Below-recommendation activity levels were likewise linked to elevated risk. Weekly exercise hours were inversely related to CMD up to ten hours per week, with evidence of a curvilinear association among women. Age-stratified analyses suggested somewhat stronger and more clearly graded associations among students aged 18-24 years; however, formal interaction analyses did not support meaningful effect modification by age group. CONCLUSIONS: These findings support a prospective association between regular physical exercise and a lower likelihood of depression and anxiety among students in higher education. The findings further suggest that consistent engagement in exercise, rather than high intensity or extreme volumes, may be particularly important, underscoring the value of promoting attainable and sustainable activity patterns in this population.