Patterns of Current and Lifetime Substance Use in Schizophrenia

A structured interview and standardized rating scales were used to assess a sample of 194 outpatients with schizophrenia in a regional Australian mental health service for substance use, abuse, and dependence. Case manager assessments and urine drug screens were also used to determine substance use. Additional measurements included demographic information, history of criminal charges, symptom self-reports, personal hopefulness, and social support. The sample was predominantly male and showed relative instability in accommodations, and almost half had a history of criminal offenses, most frequently drug or alcohol related. The 6-month and lifetime prevalence of substance abuse or dependence was 26.8 and 59.8 percent, respectively, with alcohol, cannabis, and amphetamines being the most commonly abused substances. Current users of alcohol comprised 77.3 percent and current users of other nonprescribed substances (excluding tobacco and caffeine) comprised 29.9 percent of the sample. Rates of tobacco and caffeine consumption were high. There was a moderate degree of concordance between case manager determinations of a substance-use problem and research diagnoses. Subjects with current or lifetime diagnoses of substance abuse/dependence were predominantly young, single males with higher rates of criminal charges; however, there was no evidence of increased rates of suicide attempts, hospital admissions, or daily doses of antipsychotic drugs in these groups compared with subjects with no past or current diagnosis of substance abuse or dependence. Subjects with a current diagnosis of substance use were younger at first treatment and currently more symptomatic than those with no past or current substance use diagnosis. The picture emerging from this study replicates the high rate of substance abuse in persons with schizophrenia reported in North American studies but differs from the latter in finding a slightly different pattern of substances abused (i.e., absence of cocaine), reflecting relative differences in the availability of certain drugs.