Autism may involve nerves that control touch, pain, and other sensations as well as the brain, a new study suggests.
"More than 70% of people with autism have differences in their sensory perception," said researcher Dr. Sung-Tsang Hsieh, an attending neurologist at National Taiwan University Hospital in Taipei. "For some people, even a light touch can feel unbearable while others may not even notice a cut on their foot."
If larger studies can confirm these results, he said insights into the peripheral nervous system could shed light on how autism develops and possible ways to treat the distressing sensory symptoms that most people with the disorder experience.
For the study, published online Oct. 14 in the journal Neurology, Hsieh's team compared 32 men with autism with a control group of 27 men and women who did not have autism. The control group also had no diseases affecting their peripheral nerves.
All had tests of their sensory nerves, including skin biopsies to look for damage to small fibers in their nerves. On the biopsy test, 53% of those with autism had reduced nerve fiber density, while the control group had normal levels. People with reduced nerve fiber density were more likely to feel pain from heat at a higher temperature than the control group.
"This indicates that the nerves have degenerated, similar to what happens for people with the condition of peripheral neuropathy, where the threshold for feeling heat and other sensations is higher than for other people," Hsieh said in a journal news release.
Researchers also found that the response to touch in those with autism differed. Those with normal nerves were more likely to dislike being touched and were uncomfortable with some textures. Those with nerve fiber damage preferred going barefoot and could be unaware when they were scratched or bruised.