Date of Award

6-11-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Rebecca Silton

Abstract

Working Memory (WM) refers to a cognitive system that stores and manipulates information for a brief period of time and is one of the most consistently identified neurocognitive deficits in individuals with Attention Deficit Hyperactivity Disorder (ADHD). The financial impact of ADHD is substantial, with national costs ranging from $143 billion to $266 billion. Extant experimental and meta-analytic studies have provided substantial evidence of WM deficits in children with ADHD and initial evidence suggests greater WM deficits in children with ADHD inattentive presentations (ADHD-I) relative to children with ADHD hyperactive presentations (ADHD-H) and combined presentations (ADHD-C). Yet findings from the few adult ADHD studies that have examined WM deficits in adults with ADHD, remain unclear due to the high rate of comorbidity among ADHD and anxiety and mood disorders. Co-occurring psychological disorders are likely a significant contributor to cognitive deficits in adults with ADHD, given that comorbid psychological symptoms are associated with worse clinical presentations (i.e. positive history of suicide attempts, higher disposition towards anger, and a higher rate of hospitalization and psychiatric symptoms) in individuals with ADHD. Longitudinal research suggests that increased anxiety and depressive symptoms are associated with increased ADHD symptoms across the lifespan. Thus, the present study aimed to disentangle and clarify the relation among anxiety and depression symptoms and WM performance in adults with ADHD (N = 439) who were referred for neuropsychological evaluation at a Midwestern academic medical center. A regression approach was used to examine ADHD diagnostic group (ADHD-I or ADHD-C), depression symptoms, and anxiety symptoms as predictors of WM performance. Given that education level is associated with better performance on many cognitive tasks, education was included as a covariate in the regression model. Findings revealed that anxiety and education significantly predicted WM performance, whereas depression did not, indicating distinct impacts of depression and anxiety symptoms on WM in adults with ADHD. Anxiety was associated with decreased WM performance and education was associated with increased WM performance. Together, these results illustrate the importance of clinical assessments that evaluate anxiety symptoms in adults with ADHD and underscore the need for comprehensive evaluations in both clinical and research settings. Recognizing the distinct impact of anxiety and the protective role of education on WM can facilitate the development of tailored interventions, potentially enhancing treatment outcomes.

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