Autism spectrum disorder (ASD) is an increasingly common condition affecting an estimated 1 out of 94 children (based on diagnosis at 8 years of age).
The increasing prevalence of this disorder is likely due to improved diagnostic criteria, societal awareness, and a broadening of the definition of autism to encompass Asperger’s syndrome (AS) and pervasive developmental disorder (PDD).1,2Autism is estimated to affect males over females by ratios of 6 to 1 to upward of 15 to 1.
ASD is thought to be inherited, and children with a sibling who has autism have a much greater likelihood of developing this syndrome.1 Communication deficits, difficulties with socialization, circumscribed interests or thoughts, and repetitive movements or behaviors are hallmarks of the disorder.1,3
Autism is not simply a cognitive disorder, but may also manifest visual, perceptual, auditory, and motor deficits. Although its etiology is unknown, one theory is that autism is a consequence of abnormal connectivity in the brain.3
The development of motor skills in children with ASD can be problematic, which contributes to further social isolation and learning difficulties during development. Physical therapists are often consulted to address gross motor deficits in children with ASD.
Although there has been skepticism in the past, impaired motor control is a characteristic of ASD. Currently, many children are not diagnosed with ASD until at least 3 years of age. However, studies have shown that even in infancy, symptoms of autism may be apparent, including motor impairments.
Bhat et al. stress that motor abilities are elemental to social development in children with autism, and that physical limitations affect social skills and should be addressed early in conjunction with other deficits associated with ASD development.2 Cacola et al. relate how motor problems can affect social, emotional, and academic development, which all utilize similar regions of the brain.4
As a consequence of the unpredictability of motor skills in children with autism, assessment can be complex. Baranek remarks on sensory problems that are apparent early on in children with ASD by 9-12 months of age.5
The areas of the brain involved in sensory processing include the limbic, cerebellar, and cortical regions. Abnormalities may result in under-responsiveness or over-responsiveness to sensory stimuli.
Very early on, the development of social and language skills may appear delayed, while motor skill acquisition may seem normal. As children become older, motor deficits such as low tone or dyspraxia become more apparent.
Mari et al. report that the most noticeable motor behavior in children with autism is stereotyped movements.6 However, various motor difficulties that may be less obvious but are likely related to autism involve the extrapyramidal tracts, implicating the cerebellum. This may cause problems such as abnormal gait, poor imitation of movements with dyspraxia, and perceptual-attentional deficits.
Additionally, reach-and-grasp movements are affected due to the large representation of the upper extremities on the motor and sensory cortex, particularly in persons with severe autism who may demonstrate slowed movements and decreased ability to adapt hand opening during reach as a consequence of motor planning deficits.
Early intervention to treat infants at risk for ASD, including ameliorating motor impairments that impact overall development, is imperative. It is evident that motor deficits are present in children with ASD, though there is less certainty regarding efforts at remediation to address deficits in gross motor skills.
Motor learning incorporates social interactions to address impairments in areas such as coordination, praxis, postural control, and imitation. Lindgren and Doobay found benefits, albeit modest, with interventions such as sensory stimulation, auditory integration, visual therapy, sensorimotor handling, and physical exercise, though many of the studies had small sample sizes and methodological problems.7
Yang et al. stressed the importance of gait analysis in children with ASD and the importance of treatment to improve gait and inter-limb coordination through increasing strength and control of the ankle plantarflexors.8
Duronjic and Valkova implemented an 8-week treatment program and utilized the Movement Assessment Battery for Children (MABC) to test for improved motor skills in children with ASD, noting improved motor skills with treatment programs that are tailored to the individual’s needs.9 Bhat et al. found that individually tailored methods of treating infants in the context of social interaction in tandem with perceptual-motor abilities utilizing motor control may be beneficial.2
Most children with ASD become ambulatory and may be mobile in much of their environment, leading to the notion that these children eventually attain adequate gross motor development and do not require treatment.
However, gross motor deficits are increasingly recognized as a problem in children with ASD to a varying degree. Impaired motor skills can impact overall development, not just functional mobility. Signs of motor abnormalities are beginning to be observed early in infant and toddler development.
While studies have uncovered a multiplicity of motor impairments with varying levels of severity in children with ASD, there are commonalities. Maintaining balance, motor planning, and visual-motor skills are problematic areas in many of these children.