The Role of Executive Functions in Attention Deficit Hyperactivity Disorder: Testing Predictions from Two Models

Abstract

The role of executive functions in attention deficit hyperactivity disorder (ADHD) varies considerably depending on the models of ADHD. We examined the interrelationship of two major executive functions (i.e., inhibition and working memory) with behavioral, emotional, and school problems in a group of children who had a comprehensive neuropsychological evaluation. Our sample included both children with one of ADHD subtypes and a non-clinical control group. Multiple measures of executive functions were subjected to an exploratory factor analysis, resulting in three interdependent but distinguishable underlying factors: executive concept formation, working memory, and cognitive perseveration (disinhibition). A series of predictions from two recent models of ADHD (Barkley, 1997a, 1997b; Rapport, Chung, Shore, & Isaccs, 2001) were tested through hierarchical regressions. Results indicated that, although working memory and disinhibition were significantly related to teacher-reported attention problems, working memory was a mediator, but not a moderator, of the effect of disinhibition on attention problems. Working memory was related to a variety of behavioral, emotional, and school problems that are common to children with ADHD. These results were interpreted as affirming a series of predictions from the working memory model of ADHD (Rapport et al., 2001).