Prevalence of Motor Difficulties in Autism Spectrum Disorder: Analysis of a Population‐Based Cohort

Abstract

Motor impairment is not currently included in the diagnostic criteria or evaluation of autism. This reflects the lack of large‐scale studies demonstrating its prominence to advocate for change. We examined the prevalence of motor difficulties at the time of diagnosis in a large sample of children with autism utilizing standardized assessment, and the relationship between motor difficulties, core autism symptomology, and other prominent clinical features. Vineland Adaptive Behavior Scales were administered to children from the Western Australian Register for Autism Spectrum Disorders aged ≤6 years (N = 2,084; 81.2% males, 18.8% females). Prevalence of motor difficulties was quantified based on scores from the motor domain of the Vineland and then compared to other domains of functioning within the Vineland (communication, daily living, and socialization), the DSM criteria, intellectual level, age, and gender. Scores on the Vineland indicated that 35.4% of the sample met criteria for motor difficulties (standard score <70), a rate almost as common as intellectual impairment (37.7%). Motor difficulties were reported by diagnosing clinicians in only 1.34% of cases. Motor difficulties were common in those cases meeting diagnostic criteria for impairments in nonverbal behavior and the presence of restricted and repetitive behaviors. The prevalence of motor difficulties also increased with increasing age of diagnosis (P < 0.001). Findings from the present study highlight the need for further consideration of motor difficulties as a distinct specifier within the diagnostic criteria for ASD. Autism Res 2020, 13: 298–306. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary In this population‐based cohort that included 2,084 children with autism aged ≤6 years, over one‐third met the criteria for motor difficulties, a rate almost as common as intellectual disability. This study demonstrates that motor difficulties are a prominent feature of the autism phenotype requiring further consideration in both the diagnostic criteria and evaluation of autism.

A Developmental Profile of Children With Autism Spectrum Disorder in China Using the Griffiths Mental Development Scales

“…The distribution of the subscale quotients of the GMDS across different age groups suggested that locomotor skills tend to decrease in line with age at diagnosis. This pattern is consistent with findings from previous studies that motor difficulties become more pronounced with age (Landa and Garrett-Mayer, 2006;Lloyd et al, 2013;Licari et al, 2020). The transition from infancy to preschool child requires the acquisition of increasingly complex movement skills through increases in muscle strength, coordination, and stability (Licari et al, 2020).…”

“…This pattern is consistent with findings from previous studies that motor difficulties become more pronounced with age (Landa and Garrett-Mayer, 2006;Lloyd et al, 2013;Licari et al, 2020). The transition from infancy to preschool child requires the acquisition of increasingly complex movement skills through increases in muscle strength, coordination, and stability (Licari et al, 2020). If a child has challenges in acquiring simple movement skills, it will be more difficult to acquire complex movement skills during subsequent development stages.…”

“…A further consideration is that the relative developmental levels of children with ASD may be related to the age at which they are diagnosed. For instance, Licari et al (2020) analyzed the motor abilities of 2,084 autistic children younger than 6 years old, and found that approximately 30% of the children met the criteria for motor difficulties, and that the prevalence of motor difficulties increased with the age of diagnosis.…”

A Novel Chd8 Mutant Mouse Displays Altered Ultrasonic Vocalizations and Enhanced Motor Coordination

“…The lack of a strong repetitive behavior phenotype or social impairment illustrates the challenge of modeling ASD in mice using the available behavioral paradigms. Although at least one study on mouse models of ASD has considered increased rotarod performance to resemble a repetitive behavior [Rothwell et al, 2014], humans with ASD tend to show motor impairments, rather than improvements in motor function [Licari et al, 2020]. It is therefore surprising that our model showed improvements in motor function and these findings directly contradict what has been reported in several other mouse models of ASD .…”

Increased Dopamine Type 2 Gene Expression in the Dorsal Striatum in Individuals With Autism Spectrum Disorder Suggests Alterations in Indirect Pathway Signaling and Circuitry

“…Restricted repetitive behaviors, prevalent in ASD and other neurodevelopmental conditions, include stereotypy, rituals, and compulsions and have been reported to develop, in part, due to decreased indirect pathway activity in a mouse model (Tanimura et al, 2011). Recently, a large study of 2,084 children with ASD ≤6 years old measuring motor domain criteria from Vineland tests reported that 35% had significant motor difficulties with another 44% classified as moderately low skilled and included motor stereotypies (hand flapping, spinning, body rocking), and non-verbal behaviors such as use of body postures and gestures (Licari et al, 2020). While many components in the brain contribute to a variety of these motor functions, MSNs in the dorsal striatum are considered to play a prominent role.…”