DOI: 10.1007/s10802-005-0935-y Which Executive Functioning Deficits Are Associated With

This study investigated (1) whether attention deficit/hyperactivity disorder (AD/HD) is associated with executive functioning (EF) deficits while controlling for oppositional defiant disorder/conduct disorder (ODD/CD), (2) whether ODD/CD is associated with EF deficits while controlling for AD/HD, and (3) whether a combination of AD/HD and ODD/CD is associated with EF deficits (and the possibility that there is no association between EF deficits and AD/HD or ODD/CD in isolation). Subjects were 99 children ages 6–12 years. Three putative domains of EF were investigated using well-validated tests: verbal fluency, working memory, and planning. Independent of ODD/CD, AD/HD was associated with deficits in planning and working memory, but not in verbal fluency. Only teacher rated AD/HD, but not parent rated AD/HD, significantly contributed to the prediction of EF task performance. No EF deficits were associated with ODD/CD. The presence of comorbid AD/HD accounts for the EF deficits in children with comorbid AD/HD+ODD/CD. These results suggest that EF deficits are unique to AD/HD and support the model proposed by R. A. Barkley (1997). KEY WORDS: attention deficit/hyperactivity disorder; oppositional defiant disorder; conduct disorder; executive functioning; verbal fluency; working memory; planning. Attention deficit/hyperactivity disorder (AD/HD), characterized by symptoms of distractibility, hyperacti-vity, and impulsivity, is one of the most prevalent and well-studied childhood psychopathological conditions. In one of the major contemporary theoretical explanations, this disorder is postulated to arise from a deficit in executive functioning (EF) (Barkley, 1997; Pennington & Ozonoff, 1996). EF encompasses meta-cognitive processes that en-able efficient planning, execution, verification, and regu-lation of goal-directed behavior. There is no single agreed upon definition of EF. The frontal cortex and its subcorti-cal connections have been suggested to serve as the major neurological underpinnings for EF (Eslinger, 1996; Lezak