Neural and kinematic metrics of adults with and without ADHD
Date
2022
Authors
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Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Attention Deficit Hyperactivity Disorder (ADHD) is a chronic neurodevelopmental disorder that can persist across the lifespan and causes neuropsychological dysfunction. ADHD symptom endorsement changes with maturation. Executive dysfunction (EF) theory is one of the stablished theories of addressing the etiology of ADHD. We targeted both cognitive and motor components of EF. Motor impairments are one of the most common coexisting difficulties, yet rarely addressed in diagnosis and treatment. The main goal of this study was to use different fine motor, memory and writing tasks to compare functional outcomes, performance on test and measures of brain activity in the form of HbO and HbR to understand neural underlying of ADHD Brain. ☐ To address our research questions 15 individuals with confirmed ADHD and 17 adults without ADHD (age, 22 ±1.2) completed Purdue Pegboard tasks (PPT) for manual dexterity, Detailed Assessment of Speed of handwriting (DASH 17+) and n-back for working memory task. Repeated measures two-way ANOVA was performed on average HbR and HbO in PFC regions (left dorsolateral PFC, left ventrolateral PFC, right ventrolateral PFC, right dorsolateral PFC). A Bonferroni correction was used to account for multiple comparisons. ☐ Our result from aim 1 indicates that adults with ADHD may demonstrate no significant difference in PPT performance. However, the underlying fNIRS substrates show lower baseline at rest, and higher activation in the PFC and dorsolateral PFC (dlPFC) in ADHD group compared to the control group during the task accomplishment time. This confirms the compromised fine motor ability in adults ADHD. ☐ Our Results from aim 2 showed that adults with ADHD may demonstrate no significant difference in PPT performance. However kinematic metrics gave us more insight about the compromised motor abilities in ADHD. Group comparison on short and long pauses, average absolute velocity, pen down pressure, road length, peak acceleration point, relative initial slant, normalized Y jerk and straightness error during “copy best”, “copy fast” and “freewriting” demonstrated that ADHD group struggle with regulating kinematics of writing along with the task demands. Overall, they write faster, pause less, write less smoothly, and use less pressure to write. Like kinematic results, fNIRS results also confirms group differences. Prefrontal cortex is under activated during the task, which in turn indicates compromised automaticity in writing ☐ Our result from aim 3 indicates that like aim 1 & 2, group differences are not detectable by functional outcomes. However, results from fNIRS show hyperactivation of PFC. ☐ Collective findings show that motor difficulties in ADHD persist into adulthood. We demonstrated the implications and technological advances that can be used in handwriting to capture subtle differences for a better targeted, individualized treatment and interventions. This study highlighted the significant role of PFC and it’s circuitry as possible underlying mechanism of ADHD. Additionally, we emphasize that fNIRS is uniquely suitable to be utilized in ADHD population.
Description
Keywords
ADHD, fNIRS, Handwriting, Motor control