Delay Aversion in Children with ADHD: Impact of Type of Task

Etiological models of attention-deficit/hyperactivity disorder (ADHD) centered on neuropsychological processes suggest that working memory (WM) and delay aversion (DA) underlie ADHD symptoms. Evaluations of the association between DA and ADHD have been mixed, partly due to a lack of consistent usage of DA tasks. As such, the ability of these tasks to predict ADHD-related behavioral and functional impairments remains unclear. A thorough test of the internal and external validity of the most common types of DA tasks and their association with other neuropsychological processes can assist in disentangling mechanisms that may impact ADHD symptoms.

This dissertation represents three studies that investigated the cognitive, motivational, and perceptual underpinnings of ADHD. First, study I evaluated WM performance of boys with and without ADHD utilizing a latent variable approach. Findings revealed a significant overlap in WM performance for children with and without ADHD and significant associations with symptoms of ADHD (i.e., inattention and hyperactivity), regardless of diagnosis. Second, study II evaluated the association among DA, WM, and time perception within the context of stimulant medication use for children with ADHD. Findings indicated that stimulant medication improved DA and WM performance, but not time perception, with no significant correlation between DA and WM performance. Lastly, study III evaluated the association among two types of DA tasks, symptoms of ADHD, parent-rated questionnaire measures of DA and reward sensitivity after controlling WM performance. Children with and without ADHD completed the delay discounting task (DDT) and simple choice paradigm (SCP) as well as measures of WM. Findings revealed that the DDT, but not the SCP, was associated with behavioral functioning beyond what is accounted for by WM, despite a lack of diagnostic group differences.

In sum, these studies suggest that DA and WM have separate impacts on the behavioral functioning of individuals with and without ADHD. Further, these studies suggest that DA and WM are dimensional in nature, with significant heterogeneity in performance for ADHD and TD youth samples. Lastly, the DDT may be the most appropriate DA measure for school-age children that is independent of WM.

Major Professor: Dr. Raul Gonzalez