Substance Abuse and Onset of Psychotic Illness

Objective: This study examined the relationship of substance abuse history to psychotic diagnosis and clinical presentation in a sample of 188 subjects with newly diagnosed psychotic illness. Methods: Subjects were assessed using a structured diagnostic interview and clinical rating scales. The diagnosis and demographic and clinical characteristics of subjects with a substance abuse history were compared with those of subjects without a substance abuse history. Data for males and females were considered separately in most analyses. Result: Substance abuse history was unrelated to initial diagnosis, age at onset of psychotic symptoms, ratings of best and worst levels of functioning, or severity of positive symptoms. Substance abuse was significantly associated with higher anxiety and depression scores on the Brief Psychiatric Rating Scale. Males without substance abuse had more negative symptoms and were less likely to have attempted suicide than males with substance abuse. Conclusions: Substance abuse appears to have limited influence on the clinical presentation of non-substance-induced psychotic disorders.