Substance use disorders in bipolar disorders: Clinical correlates and treatment response to mood stabilizers

Background: Substance use disorders (SUD) in bipolar disorders (BD) present relevant impact on psychopathological features and illness course. The present study was aimed at analyzing the clinical correlates of this comorbidity. Methods: In- and outpatients suffering from BD were recruited. Socio-demographic and clinical characteristics were collected. Subjects underwent a psychopathological assessment evaluating affective temperaments and impulsiveness. The appraisal of treatment response to mood stabilizers was conducted with the Alda Scale. Bivariate analyses were used to compare subjects suffering from BD with (SUD-BD) or without comorbid SUD (nSUD-BD) (p<0.05). A logistic regression model was performed to identify specific correlates of SUD in BD. Results: Among the 161 included subjects, 63 (39.1%) were diagnosed with comorbid SUD. SUD-BD subjects showed younger age at onset (p = 0.003) and higher prevalence of BD type I diagnosis (BDI) (p<0.001). Furthermore, lifetime mixed features (p<0.001), psychotic symptoms (p<0.001), suicide attempts (p = 0.002), aggression (p = 0.003), antidepressant-induced manic switch (p = 0.003), and poor treatment response (p<0.001) were more frequent in the SUD-BD subgroup. At the logistic regression, SUD revealed a positive association with BD type I diagnosis (Odds Ratio (OR) 4.77, 95% CI 1.66–13.71, p = 0.004) and mixed features (OR 2.54, 95% CI 1.17–5.53, p = 0.019). Limitations: The cross-sectional study design and the relatively small sample size may limit the generalizability of the findings. The retrospective evaluation of comorbid SUD could have biased the outcome assessment. Conclusions: Subjects with BD and SUD are characterized by higher clinical severity and require careful assessment of treatment response.