Explaining heterogeneity: Latent profiles of adult attention-deficit/hyperactivity disorder

Adults with ADHD exhibit varied patterns of neurocognitive impairment, psychological comorbidities, and functional challenges. The current characterization of ADHD into three subgroups (inattentive, hyperactive/impulsive, and inattentive-hyperactive/impulsive) does not explain the heterogeneity of challenges experienced by this population. In this study, 259 adult patients [M_age = 25.94; SD = 7.83; 78% Caucasian; 54% male] referred for an ADHD evaluation were investigated, and latent profile analysis was conducted. Behavioral, psychological, and neuropsychological functioning were considered to identify subgroups before and after the removal of those failing performance validity tests (PVTs). Initial analyses revealed four distinct classes: Neuropsychiatrically Distressed (Class 1), Relative Cognitive Inefficiencies only (Class 2), Relative Cognitive Inefficiencies with Preserved Vigilance (Class 3), and Neuropsychiatrically Resilient (Class 4). The likelihood of a patient receiving an ADHD diagnosis ranged from 80% (Class 2) to 61.6% (Class 3). Sufficient task engagement ranged from 98.0% (Class 4) to 59.3% (Class 1). After removing those who failed multiple PVTs, latent classes remained relatively stable. Identification of distinct subgroups of adult patients referred for an ADHD evaluation highlights the cognitive, emotional, and behavioral heterogeneity observed in adult ADHD. Recognition of this heterogeneity will facilitate case conceptualization and improve treatment recommendations.