Patterns and Predictors of Changes in Substance Use in Individuals with Schizophrenia and Affective Disorders

OBJECTIVE: This study examined patterns and predictors of changes in substance use over one year in individuals with schizophrenia and affective disorders. We examined patterns of cocaine use over time, baseline predictors of continued cocaine use over one year, and predictors of transitions into and out of drug use and treatment. METHODS: We recruited 240 individuals with schizophrenia and affective disorders who met DSM-IV criteria for current cocaine dependence or cocaine dependence in early full or sustained full remission, and assessed them five times over twelve months. RESULTS: There was no change over time in either the proportion of the sample with at least one day of cocaine use in the past month or in the average number of days of cocaine use among those who reported any use. Baseline variables tapping actual substance use were found to predict a decreased likelihood of cocaine use. Several variables tapping actual substance use - including self- reported use of cocaine, positive urinalysis for marijuana, and positive urinalysis for cocaine - were predictive of transitions into and out of outpatient substance abuse treatment. Readiness to change variables such as self-efficacy and temptation to use drugs showed different predictive patterns for the schizophrenia and affective disorder groups. CONCLUSIONS: These findings illustrate how drug use may show a cyclical pattern for those with serious mental illness, in which more severe use - characterized by greater frequency of use and associated problems - is followed by decreased use over time.