A Systematic Review of Sensory-Based Autism Subtypes

Abstract: Purpose: Occupational therapists are often interested in providing interventions for sensory processing differences that affect children with autism. However, this population is extremely heterogeneous, leading to the exploration of different sensory-based subtypes that may help to explain differential response to intervention (Lane et al., 2014). Several subtyping schemes have been proposed, but this body of literature has not yet been compiled and reviewed. This systematic review summarizes current literature exploring the existence of sensory-based subtypes within the autism population, answering the research question: What sensory-based subtypes have been used to classify children with autism? Design: This study is a structured systematic review completed by two independent reviewers using retrospective analysis of existing studies. The compilation of articles selected for the final review process were summarized, compared and contrasted to elucidate sensory-based subtyping trends. Method: The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines were used to structure this review process, and included a search of five databases: PubMed, OT Seeker, AMED, AOTA/AJOT, and CINAHL. Included articles were published in the last 12 years, were specific to children with autism between the ages of 2-18 years old, and considered at minimum Level IV evidence. Two reviewers completed the PRISMA procedures, establishing interrater agreement before moving onto subsequent phases of the process. Of the 33 articles meeting eligibility for a full-text review, 8 matched all of the final inclusion criteria. Results: Findings indicate that sensory-based subtypes in children with autism were developed using primarily parent-report instruments that assess sensory modulation difficulties. Therefore, sensory-based subtypes were most frequently distinguished by sensory responsivity patterns (Miller et al., 2007). Several different subtyping schemes were presented, suggesting between three to five subtypes as an appropriate fit to encompass the different patterns of sensory differences seen in children with autism. Several studies suggest that there exists a subgroup of this population with typical sensory functioning, as well as a subgroup that has significant, global sensory differences (Ben-Sasson et al., 2008; Lane et al., 2014). Mixed results were found for those children who fall in between, having differences noted with only certain types of responsivity or within specific sensory domains. Conclusion: Initial findings suggest that sensory-based subtypes within the autism population may have important implications for clinical practice and future research. This collective body of evidence, although not substantive, indicates that certain subgroups of children with autism may have similar sensory profiles that can be grouped accordingly. Furthermore, service providers can consider the sensory processing characteristics of these subtypes in their approach to treatment and intervention planning. In particular, the existence of a subgroup without impairing sensory processing differences may point toward alternative interventions. In addition, researchers can utilize this summary of findings to further explore the more salient and meaningful subtype characteristics that could better homogenize subgroups and refine future subtyping schemes. Overall, although several questions still remain, sensory-based subtyping appears to have promise for informing the application of sensory-based techniques in clinical practice and for guiding subject recruitment in future research.