Recent studies have indicated that isolated delusional-like experiences (DLE) are common in the general population. Furthermore, there is preliminary evidence to suggest that these experiences are more common in those with a family history of mental disorders. We had the opportunity to explore the association between family history of a wide range of mental disorders and DLE in an Australian general population survey. The Australian National Survey of Mental Health and Wellbeing 2007 examined 8,841 adult community residents. The Composite International Diagnostic Interview was used to generate various DSM-IV lifetime diagnoses and to assess DLE. The participants were asked to report mental disorders in their first-degree relatives. The influence of family history of mental disorders on DLE endorsement was assessed with logistic regression, with adjustments for age, sex, and the presence of comorbid psychiatric diagnoses in the respondents. A family history of anxiety, depression, schizophrenia, bipolar disorder, or alcohol or illicit drug abuse/dependence was each significantly associated with endorsement of DLE, and these associations remained significant when we adjusted for the presence of mental illness in the respondents. When we examined a more restrictive definition of DLE, only a family history of depression and schizophrenia remained significantly associated with DLE. DLE are associated with a family history of a wide range of mental disorders. These findings suggest that familial factors associated with DLE may be shared with a wide range of common mental disorders.
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