Study investigates responses to pain in individuals with autism

A new study offers insights into the responses of adults with autism spectrum disorders (ASD) to painful stimuli.

Tseela Hoffman and colleagues investigated pain perception in 104 adults, 52 of whom were diagnosed with ASD. The participants with ASD, who ranged in age from 18 to 55, were matched with neurotypical controls for age and sex, and both groups had similar scores on a cognitive test.

The researchers found that participants with ASD were more likely than controls to use psychiatric medications. In addition, they rated themselves as being more anxious and having a higher sensitivity to pain and other environmental stimuli.

On sensory tests, participants with ASD and controls had similar thermal and pain detection thresholds, a finding that suggests normal functioning of the peripheral nervous system in ASD. However, when participants were exposed to various stimuli above their pain threshold, those with ASD consistently rated their pain as higher compared to controls—an indication of hypersensitivity to pain. The researchers also found that individuals with ASD were able to successfully inhibit short pain stimuli but not long-lasting pain stimuli.

Overall, the researchers say their findings suggest that individuals with ASD have a “pro-nociceptive” pain modulation profile, meaning that their brains appear more active in facilitating the experience of pain and less active in inhibiting continuous pain. This profile, they say, may increase these individuals’ risk of developing chronic pain. They also note that their findings are consistent with the theory that ASD involves an imbalance between excitation and inhibition in the brain.

The researchers conclude, “This evidence demonstrating enhanced pain sensitivity warrants changing the common belief that autistic individuals experience less pain. This misinterpretation can lead to late diagnosis and poor treatment causing suffering and exacerbating the autistic symptoms, e.g., sleep disorders, restlessness, and aggressive behaviors.”

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Editor’s Note: Mounting evidence indicates that the perception of pain by individuals with ASD can vary from person to person and may involve hypersensitivity to pain, hyposensitivity to pain, or an inability to identify the location of the pain.

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“Indifference or hypersensitivity? Solving the riddle of the pain profile in individuals with autism,” Tseela Hoffman, Tami Bar-Shalita, Yelena Granovsky, Eynat Gal, Merry Kalingel-Levi, Yael Dori, Chen Buxbaum, Natalya Yarovinsky, and Irit Weissman-Fogel, PAIN, November 2022 (free online). Address: Irit Weissman-Fogel, Department of Physical Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa, Abba Khoushy Ave 199, Haifa 3498838, Israel, ifogel@univ.haifa.ac.il.

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“New evidence questions the assumptions about pain in autism,” news release, Wolters Kluwer Health, November 30, 2022.

This article originally appeared in Autism Research Review International, Vol. 37, No. 1, 2023