Momentary Dynamics Implicate Emotional Features in the ADHD Phenotype.

Emotional dysregulation is increasingly recognized as important to the attention-deficit/hyperactivity disorder (ADHD) phenotype alongside inattention and hyperactivity-impulsivity. Studies of ADHD have relied primarily on trait-based conceptualizations that emphasize stability of symptoms across moderate developmental timescales (i.e., months to years). Trait-based conceptualizations provide a critical view but fail to account for short-term dynamic variations in the expression of ADHD symptoms and emotion. This leaves a gap in our understanding of the short-term variation in ADHD symptom expression and the dynamic relationships among ADHD symptoms and emotion. Here, we assessed caregiver report of ADHD symptoms and positive and negative emotion using ecological momentary approaches over 2 weeks in a sample of 36 children with and without ADHD between the ages of 7-12 years old. Between-person (R_KF) and within-person (R_C) reliability were estimated. Multilevel models tested specific covariation hypotheses between ADHD symptoms and emotion. Analyses confirmed that ADHD and emotion ratings were reliable as individual differences (i.e., between-person; R_KF range 0.93-1.0) and moment-to-moment change (i.e., within-person; R_c range 0.66-0.88) measures. Multilevel models found little evidence for lagged effects between domains, but consistently identified concurrent expression of ADHD symptoms and emotions; inattention covaried most strongly with negative emotion and hyperactivity-impulsivity covaried most strongly with positive emotion. Results demonstrate the importance of complementing trait-level conceptualizations with assessment of momentary dynamics. Momentary assessment suggests important covariation of ADHD symptoms and emotion as part of the ADHD phenotype.