Objective: To identify factors associated with substance misuse in first-episode patients with schizophrenia or schizoaffective disorder.
Method: Twenty-seven patients with a past or current history of substance misuse were compared with 91 patients with no history of misuse on demographic and psychopathological measures before being treated for their first episode of psychosis, and on cognitive measures after 6 months of treatment.
Results: There were no statistically significant differences between groups for sex, schizophrenia subtype, marital status, education, family history of schizophrenia, course of illness, age of onset, baseline symptoms, time to treatment response, medication side effects, attention span, memory and executive functioning. However, dual diagnosis patients were found to have a higher parental social class, better premorbid cognitive functioning, higher IQ and better language skills.
Conclusion: First-episode patients with a history of substance misuse have higher intellectual functioning, which may be associated with higher premorbid socioeconomic status and cognitive functioning.