A co-twin-control study of altered sensory processing in autism

Abstract

Individuals diagnosed with autism often describe that they process sensory information differently from others, and many experience sensory issues as problematic. For instance, an increased sensitivity to smells or sounds can make participating in social settings challenging. While sensory issues are now part of the diagnostic criteria for autism, they also co-occur with other psychiatric diagnoses such as attention deficit hyperactivity disorder and anxiety disorders. It is unclear to what extent the relationship between autism and alterations in sensory processing are due to genetics or environment. In addition, more research is needed on how autism, as compared to other diagnoses, is associated with sensory issues. Using a twin study, we found that genetic factors influenced self-reported reactivity to sensory stimuli in autism while environmental factors influenced other sensory issues (e.g. difficulties in detecting or differentiating sensory input). Hence, sensory hyper-reactivity might be an early onset core feature of autism, while other domains of alterations in sensory processing might develop later, influenced by the environment. Moreover, autism was more strongly associated with sensory issues related to increased sensitivity/reactivity as compared to other psychiatric diagnoses. However, attention deficit hyperactivity disorder was more strongly related to deficits in detecting/differentiating sensory stimuli and with an increased drive to seek sensory input. Our results indicate that sensory issues are not specific to autism, but that some aspects of altered sensory processing are more relevant for autism than for other diagnoses.

Keywords: autism spectrum disorders; behavioral genetics; environmental factors; sensory processing; sensory profile; twin design.

Figure 1.

Visualization of the unadjusted regression results. As an approximation to visualize the regression results, the four AASP quadrants (one per row) are plotted as a function of autistic traits (SRS-2). The left most column represents the unadjusted models across individuals (a, d, g, and j), where black dots represent the individuals diagnosed with ASD and gray dots those without ASD. The middle column represents the within MZ associations where twins of a pair are connected with blue lines (b, e, h, and k). The right most column represents the within DZ associations where twins of each pair are connected with a red line (c, f, i, and l).