Drug and alcohol use among patients with schizophrenia and related psychoses: levels and consequences.

Patients with schizophrenia and related psychoses frequently use, abuse and become dependent on psychoactive substances. Local surveys indicate differences in both types and patterns of substances used. A cross-sectional survey was conducted to document abuse in 207 successive outpatients presenting to a psychiatric continuing care facility in a large Canadian city. Nicotine, alcohol and cannabis were the most frequently abused substances in the cohort. Excluding nicotine, 44.9% met criteria for lifetime and 14.0% for current abuse/dependence. Cocaine, heroin, hallucinogen, amphetamine, and inhalant use were rarely reported. Patients with current substance abuse/dependence and a psychotic disorder (dual diagnosis, DD) had significantly higher Positive and Negative Symptom Scale (PANSS) positive scores than lifetime-DD or those with a single diagnosis (SD). Significantly more current-DD (69.0%) patients were depressed (HAM-D score > or =12) compared to SD (45.6%). Furthermore, current-DD (27.6%) patients were more likely than SD (4.5%) to be medication non-compliant. Patients with current-DD were more likely to smoke cigarettes (88.9%) compared to those with SD (49.6%) and they had significantly longer histories of cigarette smoking (19.1 for DD vs. 11.5 years for SD). The smoking behavior of the DD population is discussed in terms of enhanced risk for alcohol abuse, as well as effects on antipsychotic blood levels and metabolism.