INVESTIGATING SENSORY AND MOTOR DIFFERENCES IN VARYING FORCE OUTPUT IN YOUNG ADULTS WITH AND WITHOUT ADHD

Open Access
Author:
Tucker, Jacqueline Rose
Area of Honors:
Biomedical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Kristina A Neely, Thesis Supervisor
  • Jian Yang, Honors Advisor
  • Meghan Elise Vidt, Faculty Reader
Keywords:
  • grip force
  • motor control
  • sensory
  • tactile
  • attention deficit hyperactivity disorder (ADHD)
Abstract:
The overarching goal of this work is to determine whether fingertip forces are related to tactile somatosensation in adults with and without Attention Deficit/Hyperactivity Disorder (ADHD). This work is important because it could improve our understanding of the neurobiology of ADHD. There is limited literature describing somatosensation and motor control in adults with ADHD. The current study evaluates somatosensation and force output in the thumb and index finger of the right hand.This work is motivated by two previous investigations that used a similar visually guided force task (Neely et al., 2016; Neely et al., 2017). Specifically, it was reported that adults with ADHD produce more force than adults without ADHD. The current work extends previous work by investigating force output at seven force amplitudes in a similar visually guided force task, and somatosensory measures. We have three hypotheses. 1) First, we expect to confirm our previous results and to find greater variability in force output at lower amplitudes. 2) Second, we hypothesize that tactile sensitivity will be correlated with error in the low amplitude, but not high amplitude, force conditions. 3) Third, we test the hypothesis that the mean force output will be correlated with somatosensory function. Thirty-eight participants (19 ADHD), were recruited from a larger ongoing study. In the current investigation, we tested tactile sensation in the index finger, thumb, and palm regions of the right hand. To examine motor control, we tested grip strength, coordination, and visually guided grip force. Consistent with our first hypothesis, mean force, standard deviation of force, and coefficient of variability (CoV) scaled to target amplitude. Low force amplitudes were characterized by greater variability than high force amplitudes. Force variability, and other force output variables were not correlated with quantitative sensory measurements, except for rate of force decrease. Self-reported scores of sensory experiences were positively correlated with ADHD symptomology. Somatosensory measures were not correlated with self-reported sensory measures. The results of this work suggest that these clinical somatosensory measurements are not sensitive enough to detect differences in participants with and without ADHD. Rate of force decrease in a precision grip motor task could be related to poor somatosensation.