Summary: Researchers found that adults on the autism spectrum report stronger pain sensations and show reduced ability to adapt to or suppress those sensations compared with neurotypical adults. This challenges the common assumption that people with autism are indifferent to pain.
Source: Tel Aviv University
A recent laboratory study investigated how people with autism perceive pain and revealed that, on average, they experience pain more intensely and have less effective pain inhibition than people without autism.
These results contradict the commonly held notion that individuals with autism are insensitive or indifferent to pain—a misconception that can affect clinical care, caregiving, and parental responses when a person on the autism spectrum does not show pain in familiar ways.
The study was funded by the Israel Science Foundation and led by a team including Dr. Tami Bar-Shalita of the Sackler Faculty of Medicine at Tel Aviv University, in collaboration with Dr. Yelena Granovsky of the Technion and Rambam Medical Center, and Professors Irit Weissman-Fogel and Eynat Gal of the University of Haifa. The work supported doctoral projects by Tzeela Hofmann and Mary Klingel-Levy, and three articles based on these data have already been published or accepted.
The full study has been published in the peer-reviewed journal PAIN.
Dr. Bar-Shalita notes that sensory modulation difficulties affect about 10% of the general population, producing hypersensitivity that can interfere with daily functioning and reduce quality of life.
“People with sensory modulation problems often struggle to ignore or adapt to ordinary stimuli such as flickering lights, the hum of an air conditioner, or the sound of someone eating nearby,” she explains. “Previous laboratory work has shown these individuals report greater pain than people without sensory modulation challenges.”
“Because sensory modulation issues occur in 70–90% of people with autism, are part of diagnostic criteria, and correlate with condition severity, we wanted to study whether people with autism experience more pain than the general population. Until now, there has been little laboratory research directly addressing that question.”
For many years, the prevailing belief was that people with autism are less affected by pain or even indifferent to it; this idea has been reinforced by diagnostic descriptions and by observations of self-injurious behavior. However, the research team cautions that self-injury can have multiple causes. “Self-harm may represent attempts to manage or suppress internal states,” Dr. Bar-Shalita says. “In some cases, people may inflict pain to trigger physiological mechanisms like ‘pain inhibits pain’.”
This ethically approved laboratory study included the largest sample to date for pain research in autism: 52 adults diagnosed with high-functioning autism and normal intelligence, compared with 52 age- and sex-matched neurotypical controls.
Researchers used established psychophysical methods widely applied in pain research. Participants received controlled heat stimuli while a computer regulated stimulus intensity and duration; participants then rated the pain on a 0–100 scale. These quantitative sensory tests measure the relationship between a controlled stimulus and the reported sensory response.
The results were clear: adults with autism reported higher pain ratings across single, repetitive, and sustained heat stimuli. In addition, their endogenous pain inhibition mechanisms were less effective, especially for tonic (sustained) pain, which more closely resembles many clinical pain conditions.
“We performed several measures to determine whether heightened pain responses in autism reflect a sensitized nervous system, reduced inhibitory control, or both,” the team reports. “Our data indicate a combination: amplified pain signaling together with weaker inhibitory mechanisms that normally reduce responses over time.”
Dr. Bar-Shalita concludes: “Our comprehensive study of pain intensity in adults with autism challenges the view that this population is generally indifferent to pain. On the contrary, many people with autism are more sensitive to painful stimuli and less able to suppress prolonged pain responses.”
“We hope these findings increase awareness among clinicians, caregivers, and families so that pain in people with autism is recognized and treated appropriately, and so clinicians can tailor interventions to individual sensory and pain profiles.”
The research team reports that additional papers will describe brain activity patterns during pain in people with autism and will analyze subgroups within the autism spectrum with differing pain profiles.
About this ASD and pain research news
Author: Press Office
Source: Tel Aviv University
Contact: Press Office – Tel Aviv University
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Original Research: Closed access. “Indifference or hypersensitivity? Solving the riddle of the pain profile in individuals with autism” by Tami Bar-Shalita et al. PAIN
Abstract
Indifference or hypersensitivity? Solving the riddle of the pain profile in individuals with autism
Excitatory–inhibitory (E/I) imbalance is a proposed neural mechanism underlying autism spectrum disorder, but it has not been systematically evaluated in pain processing. The authors hypothesized that people with autism would show a pain modulation profile characterized by stronger facilitation and less efficient inhibition, producing a pronociceptive state.
Fifty-two adults diagnosed with autism and 52 matched healthy controls completed quantitative sensory testing to evaluate (1) pain-facilitating responses to phasic, repetitive, and tonic heat stimuli and (2) pain-inhibitory processes such as habituation and conditioned pain modulation. Participants also self-reported anxiety, pain catastrophizing, sensory sensitivity, and everyday pain sensitivity.
The autistic group reported significantly higher pain ratings for suprathreshold single, repetitive (across multiple intensities), and tonic heat stimuli. These experimental pain ratings correlated with reported sensitivity to everyday pain situations but were not explained by elevated psychological distress.
Hypersensitivity to experimental pain was associated with greater autism severity and with sensory hypersensitivity in daily life. While individuals with autism showed efficient inhibition of brief (phasic) stimuli during conditioned pain modulation, they were less effective at inhibiting tonic (sustained) pain.
In summary, consistent with an E/I imbalance model, autism is linked to a pronociceptive pain modulation profile: increased sensitivity to both everyday and experimental pain and less efficient inhibition of sustained pain, which resembles clinical pain experiences. These findings challenge the widespread assumption that people with autism are indifferent to pain and underline the need for greater awareness of pain sensitivity in autism among caregivers and healthcare providers.