Parental Mental Disorders and Offspring Mortality up to Middle Age.

Importance: Parental mental disorders are associated with increased risks of infant mortality and with several developmental, mental, and somatic health outcomes, yet their associations with long-term morality in offspring remain unknown. Objective: To investigate the associations between parental mental disorders and the risk of mortality in offspring up to middle age. Design, Setting, and Participants: This nationwide register-based cohort study used data for individuals born in Sweden from January 1973 to December 2014. Data were analyzed from October 2024 to March 2025. Exposure: Parental mental disorders identified from the Patient Register. Main Outcomes and Measures: The outcomes were offspring mortality, including deaths due to any, natural, and unnatural causes, from birth up to December 31, 2023. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% CIs for offspring mortality according to parental mental disorders. Cousin comparison analysis was performed to assess familial confounding due to genetic and shared environmental factors. Results: Among 3 548 788 offspring, 1 818 232 were male (51.2%; 635 213 exposed to parental mental disorders) and 1 730 556 were female (48.8%; 605 935 exposed to parental mental disorders). The mean (SD) age at index parental diagnosis was 15.8 (13.3) years. During a median (IQR) follow-up of 20.1 (11.5-32.5) years (age range at end of follow-up, 9-51 years), there were 12 725 deaths (7.93 per 10 000 person-years) among offspring exposed to parental mental disorders and 30 087 deaths (3.55 per 10 000 person-years) among unexposed offspring. Offspring exposed to parental mental disorders had increased risks of all-cause mortality (HR, 2.13; 95% CI, 2.08-2.18) and death due to natural (HR, 1.88; 95% CI, 1.83-1.95) and unnatural causes (HR, 2.45; 95% CI, 2.37-2.54). All major types of parental mental disorders were associated with increased risks of offspring mortality, with the HRs ranging from 1.58 (95% CI, 1.40-1.79) for eating disorders to 2.22 (95% CI, 1.89-2.62) for intellectual disability. The associations were strongest if both parents were diagnosed with mental disorders and did not differ significantly according to the affected parents' sex and the child's age at parental diagnosis. The observed associations remained similar in the cousin comparison analyses. Conclusions and Relevance: Offspring of parents with mental disorders had an increased risk of mortality up to the age of 51 years. The associations were observed for all major types of parental mental disorders and were strongest in case of unnatural deaths, especially when both parents were diagnosed with mental disorders. These findings emphasize the importance of providing support for families with parents with mental disorders; further studies are needed to investigate whether such support may reduce the risk of premature death in affected offspring.