Thermal Perceptual Thresholds are typical in Autism Spectrum Disorder but Strongly Related to Intra-individual Response Variability

Zachary J Williams,Brynna H Heflin,Samona L Davis,Carissa J Cascio,David J Moore,Christian D Okitondo,Michelle D Failla

doi:10.1038/s41598-019-49103-2

Abstract

Individuals with autism spectrum disorder (ASD) are often reported to exhibit an apparent indifference to pain or temperature. Leading models suggest that this behavior is the result of elevated perceptual thresholds for thermal stimuli, but data to support these assertions are inconclusive. An alternative proposal suggests that the sensory features of ASD arise from increased intra-individual perceptual variability. In this study, we measured method-of-limits warm and cool detection thresholds in 142 individuals (83 with ASD, 59 with typical development [TD], aged 7–54 years), testing relationships with diagnostic group, demographics, and clinical measures. We also investigated the relationship between detection thresholds and a novel measure of intra-individual (trial-to-trial) threshold variability, a putative index of “perceptual noise.” This investigation found no differences in thermal detection thresholds between individuals with ASD and typical controls, despite large differences between groups in sensory reactivity questionnaires and modest group differences in intra-individual variability. Lower performance IQ, male sex, and higher intra-individual variability in threshold estimates were the most significant predictors of elevated detection thresholds. Although no psychophysical measure was significantly correlated with questionnaire measures of sensory hyporeactivity, large intra-individual variability may partially explain the elevated psychophysical thresholds seen in a subset of the ASD population.

Highlights

Autism spectrum disorder (ASD) is a complex, heterogeneous neuropsychiatric syndrome characterized by difficulties with social communication and the presence of repetitive and stereotyped interests and behaviors[1]
Www.nature.com/scientificreports from a baseline temperature. The direction of this change is opposite for warmth and cool detection thresholds
We extended the work of prior authors by examining the degree to which psychophysical thresholds are associated with individual differences in age, sex, IQ, and common measures of autism symptomatology (ADOS-2 Calibrated Severity Score [Calibrated severity scores (CSS)]34–36, Social Responsiveness Scale – Second Edition [SRS-2]37), including sensory features (Adolescent/Adult Sensory Profile [AASP]38,39 and Sensory Profile [SP]40 quadrant scores, as well as a one-item measure of sensory hyperresponsivity derived from the SRS-2)

Summary

Introduction

Autism spectrum disorder (ASD) is a complex, heterogeneous neuropsychiatric syndrome characterized by difficulties with social communication and the presence of repetitive and stereotyped interests and behaviors[1]. We will refer to warm and cool thresholds in terms of degree of change from baseline temperature rather than absolute temperature to maximize consistency and clarity These proposed mechanisms for aberrant sensory responsivity are appropriately tested using the methods of experimental psychophysics to relate objective stimulus intensity to perceptual threshold[15]. These studies all have important limitations, including small sample sizes (≤20 ASD participants) and the failure to account for confounding variables such as age, sex, and IQ, which often differed between ASD and control groups The largest of these studies, conducted by Duerden and colleagues[18], compared method-of-limits thermal detection and pain thresholds between a group of adolescents with ASD and IQ > 70 (n = 20) and TD controls (n = 55) who were administered the same psychophysical task in a separate study. A later study that explicitly matched ASD and TD groups on verbal IQ reported no significant differences in detection thresholds across groups[20]

Methods

Results

Conclusion