Older adult patients with both psychiatric and substance abuse disorders: prevalence and health service use.

The prevalence and service use among older adults with concurrent psychiatric and substance abuse disorders (the "dually diagnosed") was examined in a cross-sectional survey of a representative national sample of Department of Veterans Affairs mental health program patients (N = 91,752). Rates of dual diagnosis declined significantly (P = 0.001) as the age of the respondents increased (26.7% of patients < 65 years; 6.9% of patients > or = 65 years). Dually diagnosed older adult patients had longer inpatient stays for substance abuse and more outpatient substance abuse visits than did non-dually diagnosed elderly patients, and more outpatient general psychiatric visits than all the contrast groups. Dual diagnosis appears less common among older compared to younger patients, although their heavy use of certain (particularly, outpatient psychiatric) services suggests that should more dually diagnosed patients survive to old age their consumption of some forms of mental health care is likely to be high.