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ORCID

http://orcid.org//0000-0002-9143-9937

Date of Award

Summer 8-15-2021

Author's School

Graduate School of Arts and Sciences

Author's Department

Psychology

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

Introduction: Symptoms of attention-deficit/hyperactivity disorder (ADHD) have been associated with alterations in functional connectivity involving networks in the developing brain that support optimal cognitive control. However, a clear profile of altered connectivity has yet to emerge, and it remains unclear whether changes in behavioral patterns such as screen time (ST) contribute to ADHD symptomatology and altered connectivity in networks that support cognitive control. The current study examined connectivity between large-scale networks associated with cognitive control (CC), measures of executive function (EF) which index CC, and ST in children with ADHD. Methods: Our sample included 11,874 children (ages 9-11, 52% male) from the ABCD study. At the time of analyses, behavioral (e.g., ST) and psychiatric (e.g., ADHD) data were available at two time points (baseline and follow-up 1 year later), and EF and neuroimaging data were available at a single time point (baseline). Resting-state fMRI scans were processed using strict motion censoring methods and graph theory metrics were calculated using the brain connectivity toolbox. Multilevel modeling analyzed the extent to which within and between network connectivity, ST, and EF were associated with ADHD. Results: Whole-brain network modularity, which indexes network segregation, was associated with ADHD symptoms and diagnosis, and ST significantly mediated this relationship. Reduced task-positive/task-negative network associations were found between the CON and DMN but not reliably between the FPN and DMN in children with ADHD. ADHD was also associated with reduced within network connectivity in FPN, DMN, and SAL, however, results were inconsistent. This study did not find evidence of disrupted engagement of the salience network (SAL) with the FPN and DMN. Discussion: In this study, ST was consistently associated with ADHD diagnosis and severity. Replicating prior literature, we observed alterations in functional connectivity involving networks that support optimal cognitive control, although specific patterns of connectivity suggest unique developmental patterns cross-sectionally. ST use mediated the relationship between ADHD symptoms and network modularity, suggesting that behavioral patterns, such as ST use may play a role in the optimal segregation of large-scale networks. Future longitudinal work is needed to characterize the developmental trajectories of the network organization of systems involved in cognitive control to determine whether activities such as screen time in childhood disrupt this maturation by replacing activities in childhood that would otherwise develop and enhance cognitive control more effectively.

Language

English (en)

Chair and Committee

Deanna M. Barch

Committee Members

Todd Braver, Joan Luby, Linda Pfiffner, Desiree White,

Available for download on Wednesday, July 26, 2023

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