Development coordination disorder in children: From motor and cognitive perspectives.

Abstract

This dissertation centers on the interaction of mobility and neuropsychological factors in children with Developmental Coordination Disorder (DCD). The Fourth Edition of the Diagnostic and Statistical Manual of Mental Disorders defines DCD as a marked impairment in the development of motor coordination that interferes with academic achievement and/or activities of daily living in the absence of discernable medical or psychiatric causes. In addition to brief neuropsychological and physical assessments, participants completed a series of stepping accuracy tasks using a walking analog to the Trail Making Test. Task One used sequential numbers to indicate the intended targets. Task Two used sequential numbers as the intended targets, along with distracter targets. Task Three used a series of alternating numbers and letters to indicate the next intended target and also had distracters. Performance on the stepping accuracy tasks was estimated using mean walking time across nine trials on each task. Based on results from a standardized developmental motor assessment and parent ratings, children were identified as DCD (n = 12, mean age 10 years, 1 month), Borderline (BOR, n = 16, mean age 10 years, 4 months) and Matched Comparison (MC, n = 14, mean age 10 years, 7 months). Groups were comparable in terms of age, gender, grade, and handedness. Children in the DCD group performed in the normal range on most neuropsychological measures, and no significant differences were found on verbal and executive functioning measures. However, the DCD group was significantly lower than the MC group on psychomotor and working memory assessments. There were no group differences in terms of walking speed or learning of the stepping accuracy task. In contrast, as the task demands increased in cognitive complexity (i.e., number-letter sequences), the DCD group's performance fell significantly below that of the MC group. Overall, lowered DCD group performance in comparison to other groups was evident on measures of psychomotor ability and working memory and on stepping accuracy tasks with a challenging cognitive component. Psychomotor performance and working memory problems may underlie the difficulties exhibited by DCD children when completing a mobility task that involves a significant cognitive load.