Background Exposure to childhood household dysfunction increases the risk of psychiatric morbidity. Although school performance also has been linked with psychiatric morbidity, limited research has considered school performance as a mediating factor. To address this gap in the literature, the current register study examined whether school performance mediates the association between childhood household dysfunction (experienced between birth and age 14 years) and psychiatric care utilisation in young adulthood.

Methods We used a Swedish cohort of 96 399 individuals born during 1987–1991. Indicators of childhood household dysfunction were familial death, parental substance abuse and psychiatric morbidity, parental somatic disease, parental criminality, parental separation/single-parent household, public assistance recipiency and residential instability. Final school grades from the 9th year of compulsory school were used to create five categories. Estimates of risk of psychiatric care utilisation (measured as inpatient, outpatient and primary care) after the age of 18 years were calculated as HRs with 95% CIs. Mediation was tested with the bootstrap approach.

Results Cumulative exposure to childhood household dysfunction was positively associated with psychiatric care utilisation. Specifically, individuals exposed to three or more indicators with incomplete school grades had the highest risk (HR=3.7 (95% CI 3.3 to 4.1) after adjusting for demographics), compared to individuals exposed to no indicators with highest grades. School performance was found to mediate the relationship.

Conclusions Our findings suggest that future efforts to prevent or mitigate the negative effects of childhood household dysfunction on psychiatric morbidity may benefit from integration of strategies that improve school performance among vulnerable youth.