The co-occurrence of common mental and physical disorders within Australian families: a national population-based...

Because comorbidity between mental and physical disorders is commonly found in patients, it would be expected that this pattern would also be reflected at the family level. During a recent population-based survey of common mental disorders, respondents were asked about the presence of selected mental and physical disorders in their relatives. The aim of this research was to describe the within-family co-occurrence of selected common physical and mental disorders in a population-based sample.

Subjects were drawn from the Australian National Survey of Mental Health and Wellbeing 2007. A modified version of the World Mental Health Survey Initiative of the Composite International Diagnostic Interview (WMH-CIDI 3.0, henceforth CIDI) was used to identify lifetime-ever common psychiatric disorders (anxiety disorders, depression, drug or alcohol disorders). The respondents were asked if any of their relatives had one of a list of psychiatric (anxiety, bipolar disorder, depression, drug or alcohol problem, schizophrenia) or general physical disorders (cancer, heart problems, intellectual disability, memory problems). We examined the relationship between the variables of interest using logistic regression, adjusting for potential confounding factors.

Compared to otherwise-well respondents, those who had a CIDI diagnosis of major depressive disorders, anxiety disorders, or drug or alcohol abuse/dependence were significantly more likely to have first-degree relatives with (a) the same diagnosis as the respondent, (b) other mental disorders not identified in the respondent, and (c) a broad range of general physical conditions.

Individuals with common mental disorders report greater familial co-occurrence for a range of mental and physical disorders. When eliciting family histories, clinicians should remain mindful that both mental and physical disorders can co-occur within families.