Introduction : Autism Spectrum Disorder (ASD) as well as other neurodevelopmental disorders present with sensory atypicalities that can affect all modalities. Recent studies have shown associations between sensory responses to the environment and social, adaptive behaviours. This study is part of a larger project aiming at better understanding different levels of sensory processing in ASD and cohorts carrying a genetic risk factor for neurodevelopmental disorders. The methods include lab-based observations, EEG, MRI and eye-tracking. This present study uses a parent report questionnaire to assess sensory features and behaviour in response to sensory stimuli.
Methodology: A total of 130 children 2 to 8 years old participated in the study. We included 74 children diagnosed with ASD, 20 children carrying a CNV at the 1q21.1 or 16p11.2 loci, and 36 healthy children. ASD children were recruited in the clinic at the Service des troubles du Spectre de l’Autisme et apparentés (STSA) after receiving a formal diagnosis of ASD. Children carrying a CNV were referred to the study by the clinical geneticist. Healthy controls were recruited in the general population though distribution of flyers to schools and paediatricians. Parents completed the Sensory Processing Measure (SPM) questionnaire. We used multivariate analyses of variance to compare the three cohorts as well as partial correlations to assess the association with clinical variables.
Results : ASD children score significantly higher on all sensory subscales of the SPM compared to the control group. The genetic cohort also scores higher than typically developing children on all scales except the touch subscale. Children with ASD and CNV only differ in sensory processing patterns for the tactile modality. Children with ASD seemed to be significantly more over-responsive to touch processing, which suggest this sensory domain to be very specific to ASD.
Discussion : this study highlight and confirm the presence of significant atypical responses to sensory stimuli in a cohort of young ASD children. abnormal responses to tactile stimuli might be specific to ASD. Touch processing plays a critical role in social and motor development and in communication abilities, thus further investigations about this sensory channel are needed. A better understanding of the underlying mechanisms of sensory processing could help adapt the environment and ideally normalize the sensory experience to alleviate downstream effect on higher order cognition in ASD children.