Examination of the Influence of Processing Speed on the Neuropsychological Performance of Attention Deficit/Hyperactivity Disorder (ADHD) Adults
Creamer, Scott Allan
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EXAMINATION OF THE INFLUENCE OF PROCESSING SPEED ON THE NEUROPSYCHOLOGICAL PERFORMANCE OF ATTENTION DEFICIT/HYPERACTIVITY DISORDER (ADHD) ADULTSAbstractby Scott Creamer, Ph.D.Washington State UniversityAugust 2013Chair: Maureen Schmitter-EdgecombeTo better understand how neuropsychological performance in adult attention deficit/hyperactivity disorder (ADHD) is related to symptom severity and processing speed, two studies were conducted. In study one, the relationship between the inattentive and hyperactive-impulsive symptom domains and attentional/frontal executive and processing speed measures was examined. Study two examined the influence of the WAIS Processing Speed Index (PSI) and Working Memory Index (WMI) scores on the California Verbal Learning Test (CVLT) and verbal fluency performance (COWA). Participants were 46 adults who were diagnosed with ADHD. Study 1 regression analyses revealed that tests of processing speed and executive functioning were differentially related to the two symptom domains in ADHD. More specifically, aspects of executive functioning (i.e., inhibition and sustained attention) were related to hyperactive-impulsive symptoms, whereas slower processing speed was associated with inattention. For Study 2, neither the PSI nor WMI were associated with the CVLT or COWA, suggesting that poorer verbal learning/memory and verbal fluency in ADHD adults is not largely attributable to working memory and processing speed deficits. Study 1 is consistent with the notion that poor inhibition may underpin attentional/frontal executive task performance in ADHD adults. Results from study 2 suggest that factors other than processing speed, working memory, and inhibition may be contributing to CVLT and COWA difficulties experienced by ADHD adults. Taken together, these findings are in line with suggestions that slower processing speed may represent a separate neuropsychological pathway in ADHD adults.