Sensory Symptoms in Autism Families

Background: Despite widespread recognition that sensory symptoms co-occur with autism, little is known about the precise nature of these symptoms or their patterning in family members. Although sensory overresponsivity is moderately heritable in families in general, genetic influences on sensory symptoms in autism families have not been studied. Understanding the origins of sensory symptoms in families with autistic probands is critical, given their probable inclusion in the upcoming DSM-V criteria.

Objectives: We studied the subscales of the Child Short Sensory Profile in relation to autism using a family study design to estimate genetic and environmental influences on sensory symptoms in families with autistic probands.

Methods: Fifty-four pairs (23 monozygotic) of proband-ascertained twins (i.e., at least one twin is autistic) and their families participated, with a mean twin age of 8:5. We classified participants as being on the autism spectrum based on the Autism Diagnostic Observation Schedule and the Social Communication Questionnaire. A parent (usually the mother) completed the Child Short Sensory Profile for each twin and any non-twin siblings and completed the Adult Sensory Profile for him or herself.

Results: As expected, twins in the autism group have significantly more sensory symptoms than  their typically developing cotwins, across all of the sensory domains (t(101) = 5.41, p < 0.0001) as well as for the specific tactile sensitivity, taste/smell sensitivity, underresponsive/seeks sensation, auditory filtering, low energy/weak,  and visual/auditory sensitivity sections of the Child Short Sensory Profile. We focus here on the summary score from all of the sensory domains. Monozygotic twins are more concordant for categorical sensory atypicality than are dizygotic twins (84% vs. 46%). When controlling for autism concordance, zygosity is not a significant predictor of twin similarity in sensory symptoms. In addition, dizygotic twins are no more similar to one another in sensory symptoms than individual twins are to their non-twin siblings. Both of these findings support the validity of the twin method for inferring genetic influences.

Conclusions: Sensory symptoms of all types measured by the Child Short Sensory Profile are elevated in autism. Monozygotic twins are more similar to one another in total sensory symptoms than dizygotic twins when at least one member of each pair qualifies for an autism diagnosis, but a rigorous estimation of genetic influences on sensory sensitivities and their association with autism awaits more comprehensive biometric modeling.