An increasing number of research studies have pointed to motor control as an area of difficulty in children with autism spectrum disorders (ASD) (Jansiewicz et al., 2006; Fuentes, Mostofsky, & Bastian, 2009). Critical questions remain regarding the profile and specificity of motor deficits in ASD.
Objectives:
To better characterize the profile of motor difficulties associated with autism using the Movement Assessment Battery for Children, 2nd Edition (Movement ABC-2, Henderson & Sugden, 2007), which assesses three different sub-categories of motor functioning: balance, manual dexterity, and aiming/catching; and, to examine the specificity of motor findings in autism by comparing performance of children with ASD with that of typically developing (TD) children as well as that of another control group with developmental motor difficulties – children with Attention Deficit/Hyperactivity Disorder (ADHD).
Methods:
Participants included 104 children, ages 8-12 years: 33 with ASD (6 female), 34 with ADHD (8 female), and 37 TD children (8 female). Groups were matched on age, gender, race, and the Perceptual Reasoning Index (PRI) of the Wechsler Intelligence Scale for Children-4th ed. (WISC-IV, Wechsler, 2003). Three-group ANOVAs were used to examine an effect of diagnosis on total and subtest scores on the Movement ABC-2, with follow-up Bonferroni-corrected post-hoc analyses of two-group comparisons.
Results:
Three-group ANOVAs revealed a significant effects of diagnosis for the components of Balance (F = 24.366, p < .001), Manual Dexterity (F = 22.609, p < .001), and Aiming and Catching (F = 8.852, p < .001). Post-hoc tests revealed that: 1) Balance: Both the ASD group (p < .001) and ADHD group (p < .001) showed significantly poorer balance compared to TD children. The ASD group also showed poorer balance compared to ADHD children (p = .037). 2) Manual Dexterity: Both the ASD group (p < .001) and ADHD group (p < .001) showed poorer manual dexterity compared to TD children, with a trend for poorer manual dexterity in the ASD group compared with the ADHD group (p = .061). 3) Aiming and Catching: The ASD group showed significantly poorer aiming and catching than the TD group (p < .001); however, there was no significant difference between the TD and ADHD groups. The ASD group also showed poorer aiming and catching than did the ADHD group (p = .035).
Conclusions:
Children with ASD and children with ADHD show significantly poorer Balance and Manual Dexterity compared with TD children. In contrast, impairment in Aiming and Catching was observed only in children with ASD (and not in ADHD). Results from Manual Dexterity and Balance component scores suggest that ADHD and ASD groups appear to differ motorically more in severity than in kind. Differences in Aiming and Catching suggest that skills involving a greater degree of visuomotor integration are particularly impaired in autism. Alternatively, given that ball games involve social interaction, it is possible that impaired aiming and catching may be a function of lack of social observation and participation.
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