What Role Do Sensory Processing Impairments Play In the Core Features of ASD?

Background: The diagnosis of ASD according to current international diagnostic criteria relies on impairments in social interaction, communication and restricted and/or repetitive behaviours.  Recent research, however, has highlighted the high prevalence of sensory processing deficits in individuals with ASD and the detrimental impact such deficits have on individuals’ functioning.  What is yet to be explored is the relationship these sensory impairments have with the core diagnostic features of ASD. 

Objectives: This study will explore the role sensory processing deficits may have in the expression of social, communicative and repetitive behaviours by looking for associations between them.  One diagnostic tool that allows separate measures of sensory processing deficits as well as the core features is the Diagnostic Interview for Social and Communication Disorders (DISCO, Wing et al., 2002).  Detailed knowledge about these relationships will be attained using the DISCO measures for both an overall measure of sensory processing and modality scores (vision, touch, audition, smell/taste, other oral, kinaesthetic and pain).  It is predicted that the core features will have differential relationships with different modalities. 

Methods: The DISCO is a semi-structured interview, which was developed through clinical experience and as such measures a broad range of items including all the core features of ASD as well as associated features such as 25 items on sensory processing.  The DISCO was completed by a parent/caregiver of 200 individuals (32-456 months) who all received an ICD-10 diagnosis of a Pervasive Developmental Disorder.  Total scores for the core features, sensory and modalities were created using the number of items rated as a ‘marked abnormality.’

Results: Multiple regression analyses revealed social interaction and repetitive behaviours scores to be significant predictors of overall sensory score.  It was also found that the three core features had different associations with the different modalities.  Social interaction was a significant predictor of vision, touch, other oral, kinaesthetic and pain.  Communication and repetitive behaviours significantly predicted smell/taste and audition and the repetitive behaviour score was also a significant predictor of vision, kinaesthetic.

Conclusions: These preliminary results indicate sensory processing deficits may play an integral role in the expression of the ‘core’ features of ASD.  Furthermore, the core features appear to differentially predict the different modalities.  These associations cannot tell us the direction between these behaviours but by incorporating sensory items into diagnostic measures more can be learnt about the developmental direction.  It is important to note the sensory items measured by the DISCO are purely sensory in nature and do not overlap with items measuring core features.  The vision items, for example, measure ‘interest in shiny objects or bright lights’, which has no overt connection to social interaction, indicating the significant relationship is due to an underlying association between managing sensory input and autistic behaviours.  This could lead to improved sensory interventions which should not only alleviate the distress but could potentially improve social-communicative functioning.  This study promotes the use of the DISCO as it allows measurement of associated items as well as specific ASD behaviours all within one tool.