Mood symptoms as mediators of the impulsivity–ADHD link in adolescents

Background The study investigated whether manic/hypomanic symptoms mediate the link between impulsivity dimensions and ADHD severity. Methods Initially, 175 adolescents aged 12–18 years were recruited; following three exclusions due to incomplete records, the final sample comprised 62 adolescents with ADHD and 110 controls. Participants and parents completed the Barratt Impulsivity Scale–Short Form (BIS), Conners-Wells Adolescent Self-Report Scale–Short Form (CASS-S), Mood Disorder Questionnaire–Parent Form (MDQ), and DSM-IV-Based Disruptive Behavior Disorders Rating Scale–Parent Form. Mediation analyses were estimated via generalized linear modeling (identity link) with bias-corrected bootstrap confidence intervals (5000 resamples) to evaluate parent-reported mood symptoms (MDQ) as a mediator between self-reported BIS dimensions and CASS-S ADHD Index scores. Results The ADHD group scored significantly higher across all impulsivity, mood, and ADHD dimensions than controls ( p ≤ .05). Additionally, MDQ scores significantly mediated the relationships between nonplanning, motor, attentional, and total impulsivity scores and ADHD severity across all models ( p ≤ .01). Direct paths remained robust, indicating partial mediation. Conclusions Manic/hypomanic symptoms partially mediate the relationship between trait impulsivity and ADHD severity dimensionally. Clinically, screening for subthreshold affective symptoms is clinically vital to limit diagnostic overshadowing and differentiate core neurodevelopmental deficits from emerging bipolar spectrum features.