Motor Performance in Young Children with An Autism Spectrum Disorder

Background: In comparison to language and social skill, individuals with an ASD have been described as having better basic motor skills. The timing and sequence of motor developmental markers have, however, been described as both delayed and qualitatively different in individuals with ASDs than that of typically developing children.  Further deficits with motor planning have also been identified. 

Objectives: The purpose of this study was to describe the motor performance skills of a large sample of children with an ASD and compare with other developmental measures.

Methods: Retrospective collection was used to gather data on 400 individuals between 3 and 6 years of age diagnosed with an ASD during a comprehensive diagnostic team evaluation at a diagnostic center specializing in autism. Each participant received a comprehensive developmental medical, psychological, speech and language, and occupational therapy evaluation.  The resultant developmental adaptive, social, communication, and motor variables yielded from this evaluation process were analyzed.  Consistent measures for all variables across subjects or cross-validation of measures was employed.  The primary motor variables were Gross Motor (GMQ) and Fine-Motor Quotients (FMQ) from the Peabody Developmental Motor Scales First (Folio & Fewell, 1983) or Second Edition (Folio & Fewell, 2000).  Additional qualitative indicators of muscle tone, strength, balance, stability, and handedness were also collected for descriptive analysis and measurement of consistency between developmental medicine and occupational therapy.

Results: The majority of the subjects demonstrated adequate strength, though presented with muscular hypotonia and delayed onset of handedness.  Although, motor skills (both gross and fine) were statistically and consistently higher than other developmental variables (language, social, adaptive), significant delays of 2 standard deviations were noted for 86.3% of the sample in gross motor skill and 88.8% for fine motor skill.  Group differences were noted by diagnosis with lower gross motor quotients noted in the autism group when compared to PDD-NOS and Asperger groups.  The Asperger group demonstrated higher fine motor quotient scores than both Autism and PDD-NOS groups.  Regarding age differences, significant FMQ differences between the 3-year-old and 4- year-old subject groups and the 3 year old and 5 year old groups, with higher 3 year old quotient scores noted than both 4 and 5 year old groups.  No age differences were noted for gross motor quotient scores.

Conclusions: Findings are consistent with previous reports of motor performance.  Motor performance deficits are demonstrated in this large sample of preschool-aged children with an autism spectrum disorder.  These motor impairments likely contribute to functional limitations in play and adaptive performance.  Further research providing a better understanding of motor aspects unique to the diagnosis may have implications for understanding neurological underpinnings, early diagnosis, and guide treatment programs.