Introduction: There are high rates of comorbid substance use amongst individuals with psychosis. The aim of the current study was to examine the prevalence and course of substance use disorders (SUD) amongst a large cohort of young people with first-episode psychosis (FEP).
Methods: Between 1998 and 2000, the Early Psychosis Prevention and Intervention Centre (EPPIC) in Melbourne admitted 786 FEP patients. Data was systematically collected from 668 patients' medical records using the Early Psychosis File Questionnaire.
Results: 61% of the 668 FEP patients met criteria for a SUD (410 with SUD cf. 258 without SUD). The most prevalent SUD at baseline were cannabis-related (67%). 72% of patients with SUD fulfilled criteria for dependence, whilst 35% also met criteria for a secondary SUD. In the majority of cases, SUD preceded the onset of psychosis by several years. At baseline, FEP patients with SUD had significantly higher severity of illness scores and lower levels of functioning. After 18 months of treatment, SUD outcomes were highly correlated with increased rates of loss to follow-up, higher number of relapses during the treatment period, lower rates of remission, higher psychopathology scores at endpoint, increased suicidal attempts during treatment and lower level of functioning. Importantly however, patients who reduced or ceased using during the treatment period had comparable outcomes to those patients without SUD.
Discussion: SUD in FEP patients is an important clinical variable associated with increased morbidity and poor symptomatic and functional outcome. Early intervention strategies that target comorbid substance use are an important component of treatment in FEP.