Dual Diagnosis in an Aging Population: Prevalence of Psychiatric Disorders, Comorbid Substance Abuse, and Mental Health Service Utilization in the Department of Veterans Affairs

Objective: In the context of an aging baby boom cohort with higher rates of substance use disorders than previous cohorts, the abuse of substances and dual diagnosis represent growing areas of concern among older adults. The aims of this study were to determine the current treated prevalence of major psychiatric illnesses, substance use disorders, and dual diagnosis across multiple age groups in a national sample of mental health patients and to examine associated service utilization. Methods: Using administrative data from specialty mental health clinics in the Department of Veterans Affairs (N = 911,725), treated prevalence of major psychiatric illnesses, substance use disorders, and dual diagnosis across multiple age groups were determined over a 1-year interval (FY 2009). Associated mental health service utilization was examined. Results: Treated prevalence of almost all major psychiatric and substance use disorders decreased with age, while dementias increased with age. Across all major psychiatric illnesses, documented comorbid substance abuse decreased with age. Those with dual diagnoses had higher utilization of outpatient services compared to those without substance use disorders. With older age, patients had fewer outpatient visits and reduced likelihood of psychiatric hospitalization, but incurred more inpatient days per episode. Conclusions: Treated prevalence of substance use disorders and dual diagnosis decreases with age, falling to approximately 10% in those older than 65. Questions remain regarding the possibility of underdiagnosis of substance use disorders in the elderly.