Substance use and psychosocial functioning in schizophrenia among new enrollees in the NIMH CATIE study

Objective: This study examined the relationship between substance use and psychosocial functioning in schizophrenia. Methods: Participants were enrolled in the Clinical Antipsychotic Trials of Intervention Effectiveness. This study used baseline assessments and examined psychosocial functioning assessed by the Quality of Life Scale. Participants were classified as being abstinent, using substances, or having a substance use disorder. Results: Of the 1,460 participants, 23 percent used substances and 37 percent had a substance use disorder. Of the 544 with a substance use disorder, 87 percent used alcohol, 44 percent used marijuana, and 36 percent used cocaine. Compared with participants who used substances, those with a substance use disorder had higher rates of polysubstance use. Compared with those who were abstinent, those who used substances had higher overall psychosocial functioning, and those with a substance use disorder had similar overall functioning but lower scores on the common objects and activities subscales. Among participants with a substance use disorder, those who used cocaine had lower overall functioning. Conclusions: Compared with abstinence, substance use and substance use disorder, unless they involved cocaine use, were generally associated with higher or equivalent overall psychosocial functioning. Patterns of substance use were similar to those in the community, suggesting that treatment of substance use disorders in schizophrenia should focus on reconnecting substance users to nonusing peer groups.