BACKGROUND Most family studies of psychiatric disorders examine one syndrome at a time, and identify probands in clinical rather than epidemiological settings.
METHOD In the National Comorbidity Survey, 5877 respondents were asked about the history of five psychiatric disorders in their parents: major depression (MD), generalised anxiety disorder (GAD), antisocial personality disorder (ASP), alcohol abuse/dependence (AAD) and drug abuse/dependence (DAD).
RESULTS Significant familial aggregation was seen for all disorders. Controlling for other disorders produced only modest reductions in the odds ratios for MD, GAD and AAD and larger reductions for ASP and DAD. The familial transmission of these disorders can be explained by underlying vulnerabilities to internalising and to externalising disorders transmitted across generations with moderate fidelity.
CONCLUSIONS Familial aggregation of common psychiatric and substance use disorders is substantial in epidemiologic samples. The examined environmental adversities account for little of the observed parent-offspring transmission of these conditions.