Sensory Processing As a Transdiagnostic Mechanism for Behavioural Outcomes in ASD and ADHD
The most commonly reported symptoms in autism spectrum disorder (ASD) are sensory processing issues. Atypical sensory processing has been found to contribute to specific aspects of autistic symptomatology, including decreases in speech perception and restricted interests and repetitive behaviours. The extent of the cascading influence that sensory issues have has yet to be determined. Furthermore, atypical sensory processing is not unique to ASD, and it is unknown whether the impact of sensory processing issues is unique to ASD. This project addresses these two outstanding research questions.
This project aims to examine the pathway from sensory processing issues to higher-order symptoms in ASD and compare this symptom trajectory between ASD and attention-deficit/hyperactivity disorder (ADHD) and their typically-developing (TD) peers.
Data were collected from 2388 participants through a large-scale, multisite data collection project. 519 participants with ASD (N=202), ADHD (N=181), or TD (N=120) completed the measures of interest on adaptive functioning (Childhood Behaviours Checklist; CBCL) and sensory processing (Short Sensory Profile; SSP) and thus, were included in this study. Differences in functioning and sensory processing were assessed using an ANOVA, and linear regressions were utilized to predict overall functioning based on sensory processing in each group. Finally, a single hierarchical regression with all clinical participants was used to assess whether sensory scores predicted CBCL scores above and beyond clinical diagnosis by entering diagnosis into the first model step and sensory processing scores into a second model step.
ANOVA results displayed significant group differences in sensory processing and adaptive functioning (Figure 1; all p-values<0.001). Post-hoc tests showed ASD and ADHD groups exhibited greater sensory-processing and behavioural issues than the TD group (all p-values<0.001). Compared to the ADHD group, the ASD group displayed significantly fewer behavioural issues (p=0.004). However, the ASD group presented with significantly greater sensory-processing issues in every subscale of the SSP (all p-values<0.004) except Auditory Filtering, where ADHD was greater than ASD (p=0.012), and Underresponsive/Seeks Sensation, where there was no difference (p=0.873).
Notably, in every group, sensory processing issues predicted total CBCL scores. In ASD and ADHD, CBCL scores were significantly driven by Tactile Sensitivity, Underresponsiveness, and Auditory Filtering, whereas the relationship in the TD group was driven by Tactile Sensitivity, Auditory Filtering, and Movement Sensitivity (see Table 1). The final hierarchical regression including all clinical participants found that sensory processing abilities predicted CBCL total scores above and beyond what was predicted by diagnostic group (Step1(Diagnosis): R2=0.021, F-Change(1,382)=8.373, p=0.004; Step2(SSP): R2=0.417, F-Change(7,375)=36.320, p<0.001).
Individuals with ASD have unique behavioural and sensory processing issues relative to TD individuals and individuals with ADHD. Interestingly, sensory processing issues predict functional abilities in ASD as well as the other diagnostic groups. Despite unique sensory profiles between ASD and ADHD, the manner with which sensory issues relate to behavioural outcomes appears to be quite similar between ASD and ADHD. Therefore, although ASD and ADHD have their own distinct sensory symptom profile, sensory processing may act as a transdiagnostic mechanism that predicts outcome severity in various diagnostic groups.
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