Attention and Executive Functions Performance in Postsecondary Students with AD/HD and Dyslexia
Silvestri, Robert Joseph
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There is a dearth of studies investigating attention and cognitive executive functions (EFs) in adults with Attention Deficit/Hyperactivity Disorder (AD/HD), dyslexia, and AD/HD with comorbid dyslexia. Of the available studies, few have compared cognitive performance based on comprehensive theoretical models of attention and EFs and addressed methodological limitations of past research (e.g., sample inclusion and task validity confounds). This dissertation reports the findings from two studies which examined attention performance and performance pertaining to EFs and related cognitive processes of vigilance and processing speed for four groups of postsecondary students, those with AD/HD, dyslexia, AD/HD with comorbid dyslexia, and normal controls. Using a diagnostically referred sample to ensure distinct disability groups and attention and EFs measures with demonstrated construct validity, cognitive task performance was examined in Study 1 based on Posner and Raichle’s (1994) model of attention which is composed of alerting, orienting, and executive attention networks. In Study 2, Pennington and Ozonoff’s (1996) conceptualization of EFs that includes inhibition, set shifting, and working memory components was applied to the students’ performance on attention, EFs (inhibition, set shifting, and working memory), vigilance, and processing speed measures. Results from the two studies showed that the groups with attention deficits (AD/HD and comorbid groups) exhibited vigilance, executive attention, and EFs deficits related to inhibition and set shifting. The groups with reading impairments (dyslexic and comorbid groups) displayed a specific EF deficit in auditory working memory and a processing speed response time deficit. The common etiology hypothesis, which posits that cognitive deficits in comorbid groups are the sum of deficits found in AD/HD and dyslexia alone, best described the performance of the comorbid group. The results are discussed with respect to identification/assessment, compensatory strategies, and educational interventions in postsecondary students with AD/HD and dyslexia. The studies emphasize that comparing cognitive performance based on comprehensive theoretical models of attention and EFs and addressing sample inclusion and task validity confounds can effectively delineate cognitive deficits in adults with AD/HD and dyslexia.