Objective: This study examined the relationship between severity of illicit substance use at the time of study entry in a sample of patients diagnosed with schizophrenia and 18-month longitudinal outcomes, including psychopathology, depression, neurocognition, and quality of life. Methods: Subjects in the Clinical Antipsychotic Trials of Intervention Effectiveness (N = 1432) were divided into three groups according to baseline data: (1) those with moderate/severe drug use, (2) those with mild drug use, and (3) non-users of illicit substances. The groups were compared on other baseline characteristics. Mixed model analysis was used to compare outcomes between the groups using all available outcome data over 18. months, controlling for potential confounding baseline characteristics. Least square means were compared between pairs of groups in the mixed models. Results: Significantly poorer outcomes were observed in the domains of psychosis, symptoms of depression, and quality of life for moderate/severe drug users in comparison with both mild users and abstainers. No significant differences were found on neurocognitive functioning or days of employment. Conclusions: This study suggests that drug use-related impairment co-morbid with schizophrenia may not be a function of use per se but rather, of the severity of use. It highlights the importance of comprehensive assessment and treatment of illicit substance abuse in schizophrenia. Long-term treatment approaches that integrate harm reduction strategies may offer promise in maximizing positive outcomes for such dually diagnosed patients.
Bibliographical noteFunding Information:
Dr. Rosenheck reports having received research funding from AstraZeneca Pharmaceuticals LP, Bristol-Myers Squibb, and Eli Lilly and Co.; and consulting fees from Bristol-Myers Squibb, Eli Lilly and Co., and Janssen Pharmaceutica Products. Dr. Swartz reports having received research funding from Eli Lilly and Co., and consulting and educational fees from AstraZeneca Pharmaceuticals LP, Bristol-Myers Squibb, Eli Lilly and Co., and Pfizer Inc. Dr. Keefe reports having received research funding from AstraZeneca, Eli Lilly and Co., and Janssen Pharmaceutica; consulting fees or advisory board payments from Forest Labs, Eli Lilly and Co., Janssen Pharmaceutica, Pfizer Inc., and Bristol-Myers Squibb; and lecture fees from Eli Lilly and Co. and Janssen Pharmaceutica. Dr. McEvoy reports having received research funding from AstraZeneca, Forest Research Institute, Eli Lilly and Co., Janssen Pharmaceutica, and Pfizer Inc.; consulting or advisory board fees from Pfizer Inc. and Bristol-Myers Squibb; and lecture fees from Janssen Pharmaceutica and Bristol-Myers Squibb. Dr. Stroup reports having received research funding from Eli Lilly and Co.; and consulting fees from Janssen Pharmaceutica Products, GlaxoSmithKline, and Bristol-Myers Squibb. Drs. Kerfoot and Petrakis declare that they have no conflicts of interest.
This research was supported by the Advanced Fellowship Program in Mental Illness Research and Treatment of the U.S. Department of Veterans Affairs Office of Academic Affiliations .
This article was based on results from the Clinical Antipsychotic Trials of Intervention Effectiveness project, supported with Federal funds from the National Institute of Mental Health under contract NO1 MH90001. AstraZeneca Pharmaceuticals LP, Bristol-Myers Squibb Company, Forest Pharmaceuticals, Inc., Janssen Pharmaceutica Products, L.P., Eli Lilly and Company, Otsuka Pharmaceutical Co., Ltd., Pfizer Inc., and Zenith Goldline Pharmaceuticals, Inc., provided medications for the studies.
- Dual diagnosis
- Substance abuse