Patterns of substance abuse in schizophrenia: nature and significance.

Recent literature suggests that the increasingly prevalent problem of substance abuse may have important implications for the symptoms and course of schizophrenia. To further examine the impact of substance abuse on this disorder, the clinical and research charts of 67 schizophrenic patients admitted to the Schizophrenia Program of the University of Michigan between 1987 and 1990 were reviewed and data on symptomatology, history of substance use, age at onset and first hospitalization, and family psychiatric history were gleaned. This information was analyzed with respect to clinical, demographic, and outcome variables with the following findings: (i) female subjects abused substances at a much lower rate (20%) than male subjects (48%); (ii) substance-abusing patients with schizophrenia had lower pre- and post-treatment Hamilton Rating Scale of Depression scores, poorer post-discharge treatment compliance, and were younger at first hospitalization than were non-abusing patients; (iii) the most often abused substance was cannabis (28%) followed closely by alcohol (21%), with cocaine, hallucinogens, and stimulants all abused by significantly fewer patients; (iv) rates of family history of schizophrenia were similar in substance-abusing and non-substance-abusing schizophrenic patients. These data suggest that substance abuse may not be etiologically related to schizophrenia but influences the onset, course, and symptomatology of schizophrenia.