Sensory Responsiveness In Sibling Pairs Concordant and Discordant for ASD

Background:   For children with autism spectrum disorders (ASD), atypical sensory responsiveness is much more common than among children unaffected with ASD. Although numerous studies have examined the social abilities of siblings of children with ASD, none have examined their sensory characteristics.  An aggregation of sub clinical autistic social impairment traits have been found in unaffected family members of children with ASD, suggesting that such impairment constitutes an autism endophenotype (trait that is associated with a diagnosis, is heritable, and manifests in family members with or without the diagnosis).  It is important to better understand if patterns of atypical sensory processing occur in unaffected members of ASD families to better understand the heritability of this trait. 

Sensory scores have been shown to improve with increased age in previous studies that included children under the age of 18 years with ASD, but not in studies of adults. Most studies have concentrated on either children under or over age 10 because of separate sensory assessments that were standardized for those age groups, while other studies have used assessments well above their standardized age range, so the trajectory of sensory responsiveness is not clear. 

Objectives:  This study examined the sensory responsiveness of sibling pairs in children from families with ASD to better understand the heritability of atypical sensory responsiveness in these families.  In addition, differences in sensory responsiveness patterns were examined across ages.

Methods: Sensory Profile Child Questionnaires or Adolescent/Adult Sensory Profile Questionnaires were completed by parents of 146 children between age 4 and 23 (96 with an ASD diagnosis, 50 unaffected siblings; 30% African American, 69% Caucasian, 1% Asian).  Z-scores were used for statistical analyses.  Levels of responsiveness for the four sensory quadrants (overall patterns of responses: low registration, sensation seeking, sensory sensitivity, sensation avoiding) and five sensory domains (responses to specific types of sensory input: auditory, visual, touch, vestibular, taste/smell) were compared between siblings and across ages. 

Results:  Sensory responsiveness quadrant and domain Z-scores of ASD-affected children substantially deviated from published norms, but those of unaffected siblings did not.  Sensory quadrant scores significantly improved as a function of advancing age across all 4 quadrants among children with ASD.

Conclusions:  Atypical sensory responsiveness is a developmentally-sensitive trait marker in ASD, but does not appear to constitute an endophenotype.