“…Support for impulsivity as a bridge between ADHD and ODD One element of both ADHD and ODD that may play a key role in their comorbidity and relationship with social impairment is impulsivity, which has been found to play a key role in the etiology of both disorders (Beauchaine, Zisner, & Sauder, 2017) and social impairment (Barkley, 1997). These findings have been seen in cross-sectional studies that used samples ranging from preschool through young adulthood (Martel, Gremillion, Roberts, von Eye, & Nigg, 2010;Martel, Levinson, Langer, & Nigg, 2016;Martel, Levinson, Lee, & Smith, 2017) and in longitudinal work where hyperactive/impulsive ADHD symptoms, together, predict ODD behaviors (Ahmad & Hinshaw, 2017;Bell et al, 2022;Burns & Walsh, 2002). One neurobiological theory underlying such findings is that delays in cortical maturation that characterize ADHD and associated DBD (e.g., ODD) contribute to increased levels of impulsivity particularly in adolescence (Nigg & Casey, 2005;Shaw et al, 2007).…”