Circulating cytokine levels are associated with symptoms of depression and anxiety among people with alcohol and drug use disorders

Background: Psychological distress is common among people with a substance abuse disorder in treatment. Identifying correlates of psychological distress may serve as points of intervention to improve substance abuse treatment outcomes. Immune function measured as cytokine levels have been associated with psychological distress, but this association remains unexplored among people with a substance abuse disorder in treatment. This study aimed to examine whether cytokine levels in patients treated for a substance use disorder were related to depression, anxiety, and overall psychological distress, and to observe these associations separately among people with a past year alcohol use disorder and those with a past year drug use disorder. Methods: We collected cross-sectional data from 80 inpatients at five alcohol and substance abuse treatment centers in Norway. We determined alcohol and drug diagnoses, and assessed symptoms of depression, anxiety, and overall psychological distress. We tested blood samples for IL-1, IL-6, TNF-alpha, INF-gamma, and IL-10. We used multivariate linear regressions to examine the associations between cytokine levels and psychological distress measures. Results: All cytokines were significantly and positively associated with depression score. INF-gamma was significantly and negatively associated with anxiety, and IL-6 was significantly and positively associated psychological distress. Among people with only an alcohol use disorder, IL-6 was positively associated with depression and psychological distress scores, and IL-10 was negatively associated with anxiety score. Among people with only a drug use disorder, TNF-alpha was positively associated with depression score. Conclusion: The relationship between immune function and psychological distress is robust in the context of substance abuse, and further research is warranted.