Behavioral and Neural Sensory Processing in Young Adults With Autism Spectrum Disorder

PURPOSE: This study evaluated differences in behavioral and neural sensory processing in young adults with high-functioning autism spectrum disorder (ASD) compared with neurotypical peers. We also examined the impact of directing attention to auditory stimuli during sensory gating for both groups. Sensory gating is a neural process that filters out irrelevant stimuli and prevents sensory overload of higher cognitive functions.

RATIONALE: Attention is critical for everyday occupations. Studies have shown that attention influences every stage of sensory processing. However, the findings of research examining the influence of attention on sensory gating are mixed. Moreover, there is limited research examining sensory processing in young adults with ASD.

METHOD: This study used a cross-sectional, quasi-experimental quantitative design with convenience sampling. Participants included 14 young adults (aged 17–30 years) with ASD and 14 neurotypical adults. To assess sensory gating, electroencephalography data were recorded while participants were presented with two conditions of 80 pairs of click stimuli with 40 randomly interspersed single clicks. During the first condition (passive), participants were presented with the clicks and no motor response was required. For the second condition (active), participants were asked to press a button only after the single clicks but not after paired clicks. Sensory gating was measured by the reduction in the P50 amplitude to the second click (C2) compared with the first click (C1; C2/C1 ratio). Behavioral sensory processing was assessed using the Adolescent/Adult Sensory Profile (AASP). To examine the effect of directing attention to stimuli, a 2 (Condition) × 2 (Clicks) × 2 (Group) analysis of variance (ANOVA) using P50 amplitude was conducted. Independent samples t tests were used to examine group differences on the AASP.

RESULTS: The ANOVA revealed a significant interaction effect of Clicks × Group, F(1, 26) = 7.31, p = .02, η _p ² = .19, indicating that participants with ASD had significantly smaller amplitudes to the click stimuli compared with neurotypical peers regardless of condition. Condition × Clicks interaction was also significant, F(1, 26) = 7.68, p = .01, η _p ² = .23, indicating that all participants had more robust gating in the passive condition than in the active condition. Main effect of group was not significant, F(1, 26) = 2.95, p = .09, η _p ² = .10, with the current sample because of low power. However, the means of the gating ratios indicate that participants with ASD (passive M = .49, SD = .34; active M = .70, SD = .33) had less robust gating in the passive and active conditions compared with the neurotypical group (passive M = .38, SD = .15; active M = .53, SD = .14). Analysis of AASP total scores indicated that participants with ASD had significant deficits in sensory processing compared with the control group, t(26) = –2.24, p = .03. Participants with ASD had significantly greater deficits in the low registration, sensation seeking, and sensation avoiding domains (p < .05), as well as greater deficits in the sensory sensitivity domain that approached significance (p = .06).

CONCLUSION: Results from this study indicate that young adults with ASD have reduced neural processing of auditory stimuli. Additionally, directing attention toward the click stimuli significantly reduced sensory gating at the early P50 event-related potential component in both neurotypical adults and adults with ASD. Behavioral measures of sensory processing indicated significant deficits in several sensory domains in young adults with ASD.

IMPACT STATEMENT: The results of this study provide information about how behavioral and neural sensory processing challenges might affect quality of life for transitioning youth with high-functioning ASD as they advance to postsecondary education and supportive or independent employment.

References

Marco, E. J., Hinkley, L. B., Hill, S. S., & Nagarajan, S. S. (2011). Sensory processing in autism: A review of neurophysiologic findings. Pediatric Research, 69, 48R–54R. https://doi.org/10.1203/PDR.0b013e3182130c54

Tavassoli, T., Miller, L. J., Schoen, S. A., Nielsen, D. M., & Baron-Cohen, S. (2014). Sensory over-responsivity in adults with autism spectrum conditions. Autism, 18, 428–432. https://doi.org/10.1177/1362361313477246