The relationship between impulsive behaviors and adult attention-deficit/hyperactivity disorder symptoms in bipolar disorder

Objective This study aimed to examine the relationship between impulsivity and adult Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms in euthymic patients with Bipolar Disorder (BD) Type I. Methods One hundred and eleven outpatients diagnosed with BD Type I according to DSM-5 criteria, scoring ≤7 on the Hamilton Depression Rating Scale (HAM-D) and ≤5 on the Young Mania Rating Scale (YMRS), and in remission for at least two months were included. Impulsivity was assessed with the Barratt Impulsiveness Scale-11 (BIS-11) and ADHD symptoms with the Adult ADHD Self-Report Scale (ASRS). Associations were evaluated with Spearman correlation analysis with Benjamini–Hochberg false discovery rate (FDR) correction, and hierarchical multivariable linear regression. Sensitivity analyses addressed item-content overlap, influential observations, and medication effects. Results A strong positive correlation was found between BIS-11 total and ASRS total scores (ρ=0.722; q<0.001); the ASRS Inattention and Hyperactivity-Impulsivity subscales were themselves moderately intercorrelated (ρ=0.600; p<0.001). Only 18.9% of patients scored ≥72 on the BIS-11 (clinically significant range) and 28.8% screened positive on ASRS Part A. In the final regression model, ASRS total score was the strongest independent predictor of BIS-11 total score (B = 0.734; β=0.676; p<0.001), together with Young Mania Rating Scale score (β=0.170; p=0.018; R 2 =0.573), an association that strengthened after excluding influential observations and after dichotomization (both p<0.01); variance inflation factors (1.04–2.61) indicated no multicollinearity. Both ASRS subscales remained independent predictors in subscale analysis (Hyperactivity-Impulsivity β=0.436; Inattention β=0.317; both p<0.001). The association persisted after removing shared item content (ρ=0.605; p<0.001), excluding influential observations, and adjusting for treatment regimen. Conclusion In euthymic BD Type I patients, self-reported impulsivity showed a strong, independent association with self-reported adult ADHD symptom burden, particularly the hyperactivity-impulsivity dimension, robust across sensitivity analyses. Because ADHD symptoms were assessed only by self-report screening, without a structured diagnostic interview, and because the design is cross-sectional, these findings reflect a symptom-level, not diagnostic, association and do not establish causality. They nonetheless support considering ADHD symptoms in the routine clinical evaluation of euthymic BD Type I patients.