Background: Difficulties in visual behaviour are frequently reported in children with autism spectrum disorder (ASD), as well as motor impairments, which several authors described as pervasive in this population. Moreover, early visual-motor abilities predict social communication skills during childhood. However, although the importance of sensory-motor coordination is recognized in neurodevelopment, its evaluation is not always considered, particularly in low-functioning ASD individuals. Conversely, visuomotor assessment could play a crucial role in planning specific interventions, in particular in ASD children with intellectual disability who show worse difficulties in adaptation to the social environment.

Objectives: To assess visual-motor coordination in children and adolescents with autism spectrum disorder and intellectual disability.

Methods: Thirty low-functioning ASD subjects (age range: 5-13 years; 23 males) were recruited. Global functioning was investigated using the Vineland-II - Adaptive Behaviour Scale and Childhood Autism Rating Scale – Second Edition (CARS-2). Sensory Profile - Second Edition (SP-2) and Repetitive Behaviour Scale - Revised (RBSR) questionnaires were administered to caregivers to investigate the sensory-motor profile. Moreover, neuro-visual assessment, including ocular motility (i.e. visual pursuit and saccadic movements), visual acuity resolution, stereopsis, visual field and contrast sensitivity, and the Developmental Coordination Disorder Questionnaire (DCD-Q) used as a checklist were performed by neuro-psychomotor therapists with specific expertise. The Spearman Correlation Test was used to analyze the relationship between different outcome measures. A p-value <0.05 was considered as significant.

Results: In our sample, 53.33% of children showed difficulties in visual pursuit, 40% showed dysfunctions in saccadic movements, and 23.33% deficit in contrast sensitivity. Moreover, a partial correlation analysis, corrected for the severity of autistic symptoms, showed that a more compromised neuro-visual profile seemed to correlate to a higher visual reactivity at SP-2 (rho= -0.382; p=0.048). CARS-2 scores were negatively correlated to total and subtotal DCD-Q scores (rho= -0.773; p<0.001), to Vineland Motor Subscale (rho= -0.641; p<0.001) and Vineland Daily-life Abilities Subscale (rho= -0.408; p=0.025) (see Figure 1). There were no correlations between CARS-2 scores and the other Vineland subscales. Finally, partial correlation analysis, corrected for age, highlighted that poorer motor performances at the general motor coordination subscale of DCD-Q were negatively related to higher intensity of stereotyped behaviours (rho= -0.385; p=0.028) and to higher intensity (rho= -0.553; p=0.002) and frequency (rho= -0.505; p=0.005) of self-injures behaviours assessed with the RBSR questionnaire. Similarly, poorer performances at the fine motricity subscale of DCD-Q were negatively correlated to higher intensity (rho= -0.430; p=0.020) and frequency of stereotyped behaviours (rho= -0.386; p=0.038) and to higher intensity (rho= -0.412; p=0.027) and frequency of self-injuries behaviours (rho= -0.386; p=0.039).

Conclusions: Our findings highlight the frequent presence of visual and motor impairments in children and adolescents with ASD and intellectual disability. Since visual-motor difficulties in low-functioning ASD children may be considered a clinical sign of difficulty integrating perception with action to control movement, with cascading effects on overall functioning, these results emphasize the link between motor and "core" symptoms in ASD and underline the importance of explicitly considering visual-motor skills in early interventions, as in low-functioning children.

Notes:

(1)Autism Research Unit, Villa Santa Maria Institute, Tavernerio, Como, Italy, (2)School of Medicine and Surgery, University of Milano-Bicocca, Milano, Milano, Italy, (3)PhD Program in Neuroscience, University of Milano-Bicocca, Milano, Milano, Italy, (4)Autism Research Unit, Villa Santa Maria SCS, Tavernerio, Como, Italy, (5)Autism Research Unit, Villa Santa Maria SCS, Tavernerio, Italy