Background: Despite several studies highlight the presence of sensory and motor impairments in a high proportion of individuals with autism, studies aimed at evaluating both sensory and motor features are scarce in the literature. Moreover, children and adolescents with ASD and intellectual disability, who represent a significant proportion of the ASD population, are underrepresented in autism research.

Objectives: to evaluate the sensory-motor features of autistic individuals with intellectual disability, and to verify their relationship with autism severity (AS), adaptive behaviour (AB), and restricted and repetitive behaviour (RRB).

Methods: Thirty-eight ASD subjects (age range: 5-14.06 years; 25 males) diagnosed according to DSM-5 criteria were recruited. Clinical characteristics such as non-verbal IQ, AS, AB and RRB were collected using the Raven Coloured Progressive Matrices (RCPM), Childhood Autism Rating Scale – Second Edition (CARS-2), Vineland-II Adaptive Behaviour Scale, and Repetitive Behaviour Scale Revised (RBS-R), respectively. The sensory-motor profile was investigated using the Sensory Profile - Second Edition (SP-2) and the Developmental Coordination Disorder Questionnaire (DCD-Q). The Spearman Correlation Test was used to analyse relationships between different outcome measures. A p-value <0.05 was considered significant.

Results: The CARS-2, RCPM, Vineland-II total, and RBS-R total scores were, on average, 40.32+/-6.99, 70.79+/-19.37, 27.92+/-11.83 and 25.92+/-12.53, respectively. The DCD-Q total mean score was 38.39+/-11.36; 30 of 38 individuals were identified as “suspected of DCD”. Table 1 summarises the SP-2 sample results. The “Sensory quadrant” mean scores were in the “More than others” range in 3/4 quadrants (Seeking, Sensitivity and Registration). The “Sensory section” mean scores were in the “More than others” range in 2/6 sections (Touch and Oral). The “Behavioral section” mean scores were in the “More than others” range in 2/3 sections (Social/Emotional and Attentional). The significant correlations between study variables are reported in Table 2. Correlation between SP-2 categories (“Much Less”, “Less”, “Typical”, “More”, “Much more”) and DCD-Q scores show a negative correlations between DCD-Q_”Total” score and SP-2_“Social/Emotional” categories, DCD-Q_”Control of Movement” subscore and both SP-2_“Social/Emotional” and SP-2_“Avoiding” categories, and between DCD-Q_”General_Coordination” subscore and SP-2_“Registration” categories. CARS-2 score negatively correlated with the DCD-Q_Total and subtotal scores and with the SP-2_”Attentional” categories. A partial correlation analysis, corrected for age, showed a correlation between Vineland-II_“Motor_Skills” domain and the DCD-Q_Total and subtotal scores. Moreover, the Vineland-II_“Motor_Skills” domain negatively correlates with the SP- 2_“Registration” categories. Moreover, Vineland-II_“Communication” domain correlated with the DCD-Q_Total and subtotal scores, and negatively correlated with SP-2_“Conduct” categories. Regarding RRB, RBS-R “Stereotyped_Behavior” subscale score negatively correlated with DCD-Q total and subtotal scores and correlated with SP-2_“Conduct” categories. Moreover, RBS-R “Self-injurious_Behavior” domain negatively correlates with DCD-Q total and “General coordination” scores and correlates with SP-2_“Registration” and SP2_“Tactile” categories. Finally, RBS-R_“Ritualistic_Behavior” subscale score correlates with DCD-Q total and “Control_Movement” scores and with SP-2_“Seeking” categories.

Conclusions: Our findings highlight that both sensory and motor impairment can have an influence on AS, AB and RRB in children with ASD and further support the relevance of sensory-motor early intervention in children with ASD and intellectual disability.

Notes:

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