Prevalence of substance misuse among individuals with severe mental illness in São Paulo

Objectives The aims of this study were to estimate the prevalence of substance misuse among people with severe mental illness in a large urban centre of a developing country, and to investigate which are the individual characteristics associated with such comorbidity. Method A cross-sectional study was carried out in São Paulo, Brazil,with all mental health services that covered a defined geographical area.Eligible individuals had had any contact with such mental health services, had clinical diagnoses of functional psychoses, and were resident in the areas defined for the study. Use of alcohol, illegal and non-prescribed drugs, and criteria for substance misuse were assessed with a standardised clinical interview, the SCAN. Psychopathology and social adjustment were also assessed with standardised instruments. Results One hundred and ninety-two subjects were included.The prevalence of substance misuse was 10.4 % (95 % CI: 6.5–15.6),with 7.3 % fulfilling criteria for alcohol abuse or dependence, and 4.7 % fulfilling criteria for abuse or dependence of illegal or non-prescribed substances. Subjects with any abuse or dependence had lower scores for negative symptoms. Male subjects and those with a diagnosis of non-affective psychosis other than schizophrenia had higher probability of being cases of misuse of illegal or non-prescribed substances. Conclusions Prevalence of substance misuse was lower than that found in developed countries. The lack of social policies for those suffering from severe mental illnesses,with consequent dependence on family support must play a major role. Cultural factors also seem to contribute to the prevalence of substance misuse.