School performance and hospital admission due to unipolar depression: a three-generational study of social causation and social selection

Purpose Both “social causation” and “social selection” offer plausible explanations for an association between education and mental health. We aimed to explore these processes in unipolar depression, with a specific focus on school performance and family tradition of education. Method Grandchildren ( N = 28,089, 49% female, aged 13–47 years in 2002) of a cohort born in Uppsala, Sweden, in 1915–1929 were studied in national registers. We obtained data on final grade point average (GPA) in compulsory school, hospitalizations for unipolar depression, grandparental/parental education and other parental social characteristics. Hospitalization in adolescence and adulthood were studied separately, as were hospitalization for depression with or without a lifetime externalizing disorder. Results Low compulsory school GPA (1–2 SD or >2 SD below average vs. average GPA) was associated with increased rate of adolescent hospitalization for unipolar depression, both with externalizing comorbidity [hazard ratio (HR) point estimates of 66–80] and without (HR point estimates of 4–6). By contrast, low GPA was only associated with first-time hospitalization in adulthood for the subgroup with externalizing comorbidity (HR point estimates of 4–6). These associations were largely independent of family education and social characteristics. Overall, low parental/grandparental education was not related to increased rates of hospitalization. Conclusion The association between school performance and hospitalization for depression depended on adolescent hospitalization or externalizing comorbidity, suggesting that disorders with an early onset are decisive. Contrary to the social patterning of many health outcomes, low grandparental/parental education did not appear to increase the rate of hospitalization for unipolar depression in the offspring.