Sick leave due to mental disorders, morbidity and mortality: a prospective study of discordant twin pairs.

PURPOSE: To investigate if sick leave due to mental disorders increases the risk of morbidity measured by inpatient and specialized outpatient care, and mortality among women and men, independent of familial factors. METHODS: An open cohort study of 4979 twin pairs discordant for sick leave due to mental disorders was conducted in 2005-2013. Twins were followed up in the cause of death and national patient registries until the end of study, emigration, death, and inpatient and specialized outpatient care. Conditional Cox proportional hazard regression, adjusting for the familial factors shared by the twins, was used to calculate hazard ratios (HR) with 95% confidence intervals (CI). In case of non-proportional hazards, time-varying covariates were used. RESULTS: Sick leave due to mental disorders increased the risk for inpatient care among men (HR: 1.90, CI 1.66-2.17) and women (HR: 1.39, CI 1.27-1.51). For men, the risk of outpatient care was higher the first 2 years (HR: 2.08, CI 1.87-2.31), after which it was attenuated (HR: 1.32, CI 1.02-1.70). For women, the HR was 1.57 (CI 1.47-1.68) for the whole study time. There was an increased risk of death among men (HR: 2.91, CI 1.70-4.99), but not among women (HR: 0.84, CI 0.53-1.35). CONCLUSIONS: Sick leave due to mental disorders was a risk factor for mortality for men only, and increased the risk of inpatient and specialized outpatient care among both women and men, but the risks were higher for men when stratifying for sex.

The relationship between parental depressive symptoms and offspring psychopathology: evidence from a children-of-twins study and an adoption study.

BACKGROUND: Parental depressive symptoms are associated with emotional and behavioural problems in offspring. However, genetically informative studies are needed to distinguish potential causal effects from genetic confounds, and longitudinal studies are required to distinguish parent-to-child effects from child-to-parent effects. METHOD: We conducted cross-sectional analyses on a sample of Swedish twins and their adolescent offspring (n = 876 twin families), and longitudinal analyses on a US sample of children adopted at birth, their adoptive parents, and their birth mothers (n = 361 adoptive families). Depressive symptoms were measured in parents, and externalizing and internalizing problems measured in offspring. Structural equation models were fitted to the data. RESULTS: Results of model fitting suggest that associations between parental depressive symptoms and offspring internalizing and externalizing problems remain after accounting for genes shared between parent and child. Genetic transmission was not evident in the twin study but was evident in the adoption study. In the longitudinal adoption study child-to-parent effects were evident. CONCLUSIONS: We interpret the results as demonstrating that associations between parental depressive symptoms and offspring emotional and behavioural problems are not solely attributable to shared genes, and that bidirectional effects may be present in intergenerational associations.