Substance use in severe mental illness: self-medication and vulnerability factors

The aim of this article is to examine the onset and clinical correlates of substance use in patients with psychotic disorders. One hundred and eight inpatients and outpatients with DSM-IV psychotic disorders were evaluated with the SCI-SUBS, an instrument designed to explore the spectrum of substance use and its clinical correlates. Comparisons were made between subjects with (n=47) and without (n=61) a DSM-IV diagnosis of substance use disorder (SUD). In patients with an early onset of psychosis (<17 years), the onset of SUD was subsequent. Patients with SUD had higher substance sensitivity, higher sensation-seeking traits and were more likely to self-medicate than patients without SUD. The reasons for self-medication endorsed by patients with SUD included relieving depression, achieving or maintaining euphoria, improving self-confidence and social abilities. Our results, based on a cross-sectional study, suggest that early onset of psychosis, substance sensitivity and sensation-seeking traits represent vulnerability factors for SUD. The relationships between SUD and psychosis should be examined systematically and clarified in longitudinal studies.