Clinical epidemiology of comorbid dysthymia and substance disorder

The authors sought to determine the 1-year-period prevalence and demographic characteristics of comorbid substance-related disorder (SRD) and dysthymia, as well as the demographic characteristics of SRD-dysthymia patients as compared with SRD-only patients. Patients being treated at two university medical centers and abstinent less than 2 years were followed prospectively for 6 months to establish the diagnosis of dysthymia. A total of 642 patients were assessed, of whom 39 had SRD-dysthymia and 308 had SRD only. Data collection instruments included a demographic questionnaire and assessment of DSM Axis I psychiatric diagnoses. The 1-year prevalence rate was lower than noted in previous studies where there were less stringent criteria for dysthymia. The rate of dysthymia among these SRD patients closely resembled that observed in a general population study. SRD-dysthymia patients and SRD-only patients did not differ on most demographic characteristics. SRD-dysthymia is not easily detected among recovering SRD patients because of the need for lengthy observation and the absence of special demographic characteristics.