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Addiction Science Made Easy: Factors Affecting Cocaine Dependent Tobacco Smokers

Despite extensive work, there are still no FDA-approved interventions for the treatment of cocaine use disorder (CUD). Because of this, examining modifiable factors that affect CUD outcomes, and thus could be useful therapeutic targets, is clinically important. 

Sleep duration has been found to mediate the relationship between cocaine use and reduced dopamine receptors, which is predictive of relapse. Additionally, sleep disturbance has been found to predict greater cocaine use in both laboratory and outpatient studies. 

This suggests that sleep disturbance may be a useful factor to measure and target therapeutically in those who have CUD. Previous research on sleep disturbance and cocaine use relied on polysomnographic sleep assessment, which is fairly resource-intensive. From the standpoint of clinical utility, a self-report measure would be a valuable alternative. 

This ancillary study, based on CTN-0046(Smoking Cessation and Stimulant Treatment), tested the predictive validity of the Pittsburgh Sleep Quality Index (PSQI), a self-report assessment of past-month sleep quality, to determine its effectiveness in predicting outcomes in patients with CUD.

The PSQI was collected at baseline. Outcomes of interest were cocaine and drug abstinence at end-of-treatment (weeks 9-10). Potential mediators, measured in weeks 1-8, were cocaine craving and anxiety and depression symptoms. 

“Mediation analysis” was used to evaluate mediation effects separately and jointly. Mediation analysis attempts to explain “how” or “why” an effect occurs, so, in the case of this study, researchers were looking at whether sleep disturbance was a predictor of end-of-treatment abstinence and what influence the “mediators” anxiety, depression, and/or cocaine craving had on that relationship.

The majority of participants (58.3%) reported sleep disturbance at baseline. Independent of the mediators, sleep disturbance was not found to be a significant predictor of end-of-treatment abstinence. However, when the role of cocaine craving, anxiety, and depression were analyzed as potential mediators of that connection, a significantassociation between sleep quality and cocaine abstinence outcomes was revealed. 

Conclusions:This exploratory analysis suggests that there may be an indirect relationship between self-reported sleep quality and substance use outcomes in cocaine-dependent patients, mediated by craving, anxiety, and depression. This suggests that patients with CUD reporting sleep disturbance may need additional intervention to achieve cocaine and drug abstinence, relative to those without sleep disturbance. Further research to evaluate the potential of sleep disturbance as an actual therapeutic target for CUD treatment may be of interest.

Citation: Winhusen TM, Theobald J, Lewis DF. Substance use outcomes in cocaine-dependent tobacco smokers: A mediation analysis exploring the role of sleep disturbance, craving, anxiety, and depression. Journal of Substance Abuse Treatment 2019;96:53-57. [doi: 10.1016/j.jsat.2018.10.011]

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