Autism and Chronic Pain
Autism spectrum disorder (ASD) is a developmental disability characterized by social and communication impairments, restricted interests, and repetitive behaviors. More than 80% of autistic people experience sensory modulating disturbances, which in the general population is often associated with sensory and pain hypersensitivity to daily stimuli. The etiology of autism is not yet fully understood, but it is thought to be related to heterogeneous genomic factors. One of these factors is an excitatory-inhibitory (E/I) imbalance at a cellular level, which affects the global neural circuits activity and may interfere with the pain system function. This article aims to explore the connection between autism and chronic pain, focusing on the psychophysical characteristics of a potential E/I neuronal imbalance.
Pain Sensitivity in Autism
Although the prevailing assumption is that autistic individuals are hyposensitive to pain, research on pain sensitivity in autism has yielded mixed results. Some studies found no differences in pain sensitivity between autistic and healthy individuals, while others reported increased sensitivity to noxious thermal stimuli in autistic adults. The authors of the referenced article aimed to examine the functioning of facilitatory and inhibitory pain pathways in a large sample of autistic adults using a comprehensive laboratory pain battery, including static and dynamic tests, and gathering information about participant psychological distress, e.g., anxiety.
A 2022 study in Pain journal explored the functioning of facilitatory and inhibitory pain pathways in a sample of autistic adults using a comprehensive laboratory pain battery, including static and dynamic tests, and gathering information about participant psychological distress. The study found that autistic participants showed normal functioning of the peripheral nervous system based on thermal and pain thresholds. However, pain sensitivity was evident through consistent enhanced pain ratings in response to suprathreshold stimuli of different characteristics. Autistic participants also exhibited different response functions to phasic and tonic pain stimuli. While the pain inhibitory system responded efficiently to phasic stimuli, it did not efficiently respond to tonic stimuli. These findings suggest a pronociceptive pain modulation profile (PMP) in autistic individuals, comprising hypersensitivity along with inefficient functioning of the endogenous inhibition during continuous pain. The central nervous system is thought to be solely involved in the improper processing of pain stimuli in autism. Additionally, pain sensitivity in autism may be attributed to autism severity and its accompanied nonpainful
This evidence demonstrates that individuals with autism show a pronociceptive PMP, which includes hypersensitivity along with inefficient functioning of the endogenous inhibition during continuous pain. The findings warrant a change in the common belief that autistic individuals experience less pain, as this misinterpretation can lead to late diagnosis and poor treatment, causing suffering and exacerbating autistic symptoms such as sleep disorders and restlessness.
- Hoffman, Tseela; Bar-Shalita, Tami; Granovsky, Yelena; Gal, Eynat; Kalingel-Levi, Merry; Dori, Yael; Buxbaum, Chen; Yarovinsky, Natalya; Weissman-Fogel, Irit (2022-08-26). "Indifference or hypersensitivity? Solving the riddle of the pain profile in individuals with autism". Pain. doi:10.1097/j.pain.0000000000002767. ISSN 1872-6623. PMID 36730631.