OBJECTIVE: Being an offspring of parents with severe mental illness (SMI) is associated with increased risk of certain somatic illnesses, including epilepsy. We examined mortality and the full spectrum of somatic illnesses among offspring of parents with and without SMI born in Denmark between 1982 and 2012. METHODS: In a nationwide cohort study of all 2,000,669 individuals, including 47,516 individuals with a parental disposition to severe mental illness, we estimated mortality rate ratio (MRR), incidence rate ratio (IRR) and cumulative incidence fraction (CIF) of first hospital contact for a broad spectrum of somatic illnesses using Poisson’ regression adjusted for important confounders. RESULTS: During follow-up (8, 4 million person-years), exposure to severe mental illness in a parent was associated with significantly earlier first somatic contact (IRR 1.17; 95% CI 1.16-1.18) than found in those unexposed. The exposed group had higher risk of a broad spectrum of diagnoses with largest effect sizes for injuries, ill-defined conditions, infections, Central Nervous System (CNS) diseases, digestive system, circulatory system and respiratory diseases, endocrine and metabolic diseases and conditions originating in the perinatal period (all p<0.0001). Highest mortality was found for exposure to maternal bipolar disorder (MRR 2.03; 95% CI 1.50, 2.74) but significantly elevated offspring mortality was also found for parental depression. CONCLUSIONS: Our findings indicate that offspring of a parent with SMI have higher morbidity and mortality which should warrant heightened vigilance and support throughout infancy, childhood, and adolescence for families affected by severe mental illnesses.
