Motivations that maintain substance use among individuals with psychotic disorders.

This study quantitatively examined reasons for substance use among individuals with psychotic disorders and explored the relationship of these reasons to substance use problems and dependence. Sixty-nine people with psychotic disorders were interviewed using a battery of questionnaires called the Substance Use Scale for Psychosis (SUSP). Symptoms and medication side effects were also measured. A factor analysis revealed similar motives for substance use (mostly alcohol and cannabis use) as in the general population: "enhancement," "social motives," "coping with unpleasant affect," and "conformity and acceptance." A fifth factor, "relief of positive symptoms and side effects," demonstrated limited reliability. "Coping" and "enhancement" motives were found to lead to substance use problems and dependence. Mediator analysis indicated that worse symptoms lead to stronger motives for substance use, which in turn lead to stronger psychological dependence on that substance. These findings have the potential to inform effective treatment for substance use in psychosis.