Parental mental disorders and ages of onset of severe mental disorders in offspring: A nationwide family-link study.

Objective: The current study used a retrospective study design to investigate the association between age of onset of severe mental disorders in offspring and the likelihood of diagnoses of parental mental disorder.
Method: We enrolled 212,333 people with severe mental disorder, including schizophrenia, bipolar disorder (BD), or major depressive disorder (MDD) and 2,123,329 controls matched for age, sex, and demographics from the National Health Insurance Database of Taiwan. Poisson regression models were used to examine the likelihood of diagnoses of five mental disorders in their parents compared to the parents of the controls (reported as odds ratio (OR) with 95% confidence interval), including schizophrenia, BD, MDD, alcohol use disorder (AUD), and substance use disorder (SUD). The study cohort was classified into child-onset, adolescent-onset, and adult-onset groups according to the onset of severe mental disorders in the offspring.
Result: The parents of people with child-, adolescent-, and adult-onset schizophrenia (OR range: 1.73-9.08, all p < 0.05) or BD (OR range: 1.97-8.17, all p < 0.05) were more likely to be diagnosed with schizophrenia, BD, MDD, AUD, and substance use disorder (SUD) than controls except for AUD in the child-onset group. However, the parents of people with child-, adolescent-, and adult-onset depressive disorder were more likely to be diagnosed with schizophrenia, BD, MDD, AUD, and SUD (OR range: 1.82-4.76, all p < 0.05) than controls. Sub-analyses stratified by sex showed different patterns of associations between parental mental disorders and offspring mental disorders.
Conclusion: No matter when the severe mental disorder of the offsprings occurred at different onset stages, their parents had a higher likelihood of being diagnosed with schizophrenia, BD, MDD, AUD, and SUD.
Competing Interests: Declaration of competing interest No conflict of interest.
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