Date of Award

August 2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Psychology

First Advisor

Bonita P Klein-Tasman

Committee Members

W. Hobart Davies, Michelle M Loman, David C Osmon, Kristin D Smith

Abstract

Despite variability in the neurofibromatosis type 1 (NF1) cognitive phenotype, attention and executive functioning (EF) difficulties are often described, and high rates of attention-deficit/hyperactivity disorder (ADHD) have long been associated with NF1. Despite the known clinical relation between NF1 and ADHD, there is a paucity of research exploring potential factors that contribute to ADHD vulnerabilities in children and adolescents with NF1. Furthermore, recent research suggests that impairment in EF, a construct highly associated with ADHD, occurs in children with NF1 independent of ADHD diagnosis suggesting that the presence of EF impairment in children with NF1 may not be uniquely associated with ADHD. Given the complexity of EF and the relative lack of literature about factors that might contribute to EF performance in children with NF1, further research is warranted. The current study aims to characterize EF in children with NF1, compare EF from performance-based and functional measures, and explore potential neuropsychological, sociodemographic, and psychosocial factors that contribute to EF in children with NF1. Overall, results confirmed that children with NF1 demonstrate difficulty on performance and functional EF measures, and difficulties were more evident based on functional parent report of behavior. Over one-third of children with NF1 met diagnostic criteria for ADHD; however, children with NF1 as a group demonstrated similar EF profiles on performance measures, independent of ADHD diagnosis. On functional parent reported measures of EF, children with NF1 and ADHD demonstrated significantly higher levels of executive dysfunction compared to children with NF1 without ADHD. Relations between performance-based working memory and general cognitive functioning were found for children with NF1, as a group. Parent report of internalizing problems were related to parent report of functional emotional control, shifting/cognitive flexibility, and overall behavioral regulation. As hypothesized, parent reported sleep difficulties were related to functional EF. In addition, slower reaction times on a working memory task were related to parent report of snoring, and parent report of restlessness during sleep was related to functional EF. Group differences between children with NF1 who met cut-off criteria for a sleep-related breathing disorder and those that did not were apparent when examining parent report of functional inhibition, working memory, and self-monitoring difficulties. Overall, results highlight the utility of a multi-method assessment of EF and provide evidence for contributing factors of overall cognition, attention, internalizing problems, and sleep on various aspects of EF in children and adolescents with NF1.

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