Additive impulsivity and emotion dysregulation in adolescents with comorbid bipolar and substance use disorder: a...

Comorbid bipolar disorder (BD) and substance use disorder (SUD) in adolescence is associated with poor clinical outcomes, yet the independent and interactive contributions of impulsivity and emotion dysregulation remain poorly understood.

This cross-sectional study employed a 2 × 2 factorial design to examine impulsivity, measured with the Barratt Impulsiveness Scale-11, and emotion regulation difficulties, measured with the Difficulties in Emotion Regulation Scale, across four groups of adolescents (N = 128; aged 12-18 years): BD+SUD (n = 32), BD-only (n = 32), SUD-only (n = 32), and healthy controls (n = 32). All clinical participants were assessed during euthymia. Factorial analyses of covariance controlled for age, sex, residence, family structure, and income.

Significant BD × SUD interactions were found for emotion regulation, F(1,120) = 35.89, p < .001, ηp² = .230, and impulsivity, F(1,120) = 9.51, p = .002, ηp² = .073. The BD+SUD group showed the highest scores on both measures, exceeding the SUD-only group by 38.90 points on emotion dysregulation and 26.72 points on impulsivity. In the substance-using subsample (n = 64), impulsivity was the strongest predictor of substance use severity (B = 0.61, p < .001; R² = .48). The BD+SUD group also displayed earlier illness onset, mixed-feature predominance, greater polydrug use, and exclusive high-lethality suicide attempts. Low income was the strongest exploratory predictor of clinical group membership.

These findings support an additive comorbidity model in which BD and SUD jointly amplify impulsivity and emotion dysregulation, and they highlight the need for integrated, impulsivity-focused interventions in adolescents with dual diagnoses.