The relationship between symptom clusters and substance abuse in schizophrenia

Lori Logothetis (2007)

Alcohol and substance use disorders are common among individuals with schizophrenia spectrum disorders. A variety of theories including self-medication, biological, and social hypotheses have been proposed to explain this high comorbidity. The current sample consisted of 75 patients between 18 and 65 years old, who met criteria for both schizophrenia or schizoaffective disorder, and substance abuse or dependence as defined by DSM-IV. It was hypothesized that individuals with different classes of schizophrenic symptoms would demonstrate different patterns of substance use preference, that medication side effect profiles would also predict substance use preferences, and that males and females would differ with respect to their drugs of choice. With respect to the first hypothesis, the results did not support conventional clinical wisdom that patients with schizophrenia selectively self-medicate their symptoms by choosing specific drugs to alleviate specific types of symptoms. With respect to the second hypothesis, side effect profiles significantly predicted substance choice for only three of 16 comparisons: (a) participants exhibiting anhedonia were more likely to use alcohol than those who did not exhibit anhedonia, (b) lethargic patients were less likely to use cannabis than nonlethargic patients, and conversely, (c) patients experiencing insomnia were more likely to use cannabis than those who were not experiencing insomnia. With respect to the third hypothesis, there were no statistically significant gender differences in substance preferences. Recommendations for future research include (a) performing longitudinal studies to address the relationships between drug use, symptoms, and medication side effects as they may change over time, (b) using toxicology results rather than self-reports of substance use, (c) a more detailed categorization of schizophrenic symptoms, and (d) other types of substances (both legal and illicit) in relation to schizophrenic symptoms and medication side effects. Recommendations for Symptom Clusters and Substance Abuse clinical practice include (a) reconsidering the conventional wisdom that patients attempt to self medicate symptoms of schizophrenia with specific substances, and (b) considering the observed relationships between anhedonia and alcohol use, lethargy and cannabis use, and insomnia and cannabis use in treatment situations.