Perceived reasons for and consequences of substance abuse among patients with psychosis.

BACKGROUND: Substance use is a common comorbidity with psychotic illnesses. Although several theories exist to explain this link, individual reasons for use may differ. The aim of this study was to evaluate patient perceptions of the reasons for and consequences of their substance use in patients with psychosis and compare them with those of an age-, sex-, and tobacco use-matched control sample without psychosis.
METHOD: Consecutively admitted patients were divided into 2 groups, those who had substance dependence without psychosis (n = 32), admitted in our addiction unit, and those who had psychotic illness with substance dependence, admitted in our inpatient psychosis unit and referred to as the dual-diagnosis group (n = 62). Patients were administered the Schedules for Clinical Assessment in Neuropsychiatry for ICD-10 Diagnostic Criteria for Research to confirm schizophrenia, bipolar affective disorder, and substance dependence diagnoses and were asked open-ended questions to evaluate the perceived reasons for and consequences of their substance use. The study was conducted from July to September 2006.
RESULTS: There were significant differences between the 2 groups in reasons for maintenance and relapse of both cannabis use and alcohol use, the 2 most common substances. While the substance dependence without psychosis group attributed both maintenance and relapse to external factors such as nature of work, social milieu, or peer pressure, the dual-diagnosis group attributed them to internal factors such as enhancement of positive mood and alleviation of withdrawal effects.
CONCLUSIONS: Individuals with psychosis have greater vulnerability to internal factors, which may maintain substance use. Targeting perceived internal factors may play a useful role in management and possibly identification and prevention of psychosis in vulnerable individuals in the future.