Full Spectrum of Psychiatric Outcomes Among Offspring With Parental History of Mental Disorder

Context: While concordant parent/offspring risks for specific mental disorders are well established, knowledge of the broader range of psychiatric outcomes among offspring with parental history of mental disorder is lacking. Objective: To examine the full range of mental health outcomes among offspring of parents with serious and other mental disorders compared with those whose parents had no such history. Design: Population-based cohort study. Offspring were followed up from their 14th birthday for the development of mental disorders based on both outpatient and inpatient hospital data. Setting: Danish population. Participants: All offspring born in Denmark between 1980 and 1994 (N=865 078) with follow-up to December 2008. Main Outcome Measures: Incidence rates, incidence rate ratios, and cumulative incidences for offspring psychiatric outcomes. Results: Parental serious mental disorder (SMD) (nonaffective or affective psychosis) was found to be positively associated with virtually all offspring psychiatric outcomes, including those not hitherto regarded as clinically related. Offspring of parents without SMD but with a history of "other mental disorder" were also found to be at increased risk of developing a range of mental disorders. The strongest associations were found where both parents had a history of mental disorder (eg, offspring of 2 parents with SMD were 13 times more likely to develop schizophrenia). Elevated risks were not confined to concordant parent/offspring disorders (eg, offspring of 2 parents with SMD were 8 times more likely to develop substance misuse disorders). Conclusions: The impact of parental history of mental disorder was not confined to elevated offspring risk of concordant disorders but rather offspring are at increased risk of a wide range of mental disorders, particularly those with 2 affected parents. Our results imply an important role for etiological factors giving rise to broad, as well as specific, familial vulnerabilities. These findings also have potential implications for diagnostic classification.