A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Fall, 2020 | Number 4, Volume 34

ASD may involve damage to peripheral nerves

A new study from Taiwan suggests that the peripheral nervous system, which is composed of the nerves lying outside the brain and spinal column, may play a role in autism spectrum disorders (ASD). 

Yi-Ling Chien and colleagues enrolled 32 men with ASD and 27 neurotypical men and women in the study. All participants underwent tests of their sensory nerves, including skin biopsies to look for damage to the small fibers in the nerves. In addition, the researchers examined the electrical responses of nerves to heat pulses applied to the skin. Participants with ASD also filled out questionnaires about their sensory issues. 

The researchers found that 53% of individuals with autism, but no members of the control group, had reduced nerve fiber density. Members of the ASD group who had reduced nerve fiber density tended to feel pain from the heat stimulus at a higher temperature threshold than controls. Study coauthor Sung-Tsang Hsieh says, “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.” 

The researchers also found that people with ASD who had normal nerves were more likely to dislike being touched and to be bothered by certain textures, while people with ASD who exhibited nerve fiber damage were more likely to say they liked to go barefoot and to be unaware when they got scratched or bruised. 

The researchers conclude, “These observations indicated that a substantial portion of [individuals with ASD] had small fiber pathology, which was associated with tactile and autistic symptoms, providing structural and physiologic evidence for the involvement of peripheral sensory nerves in autism.”

Noting that more than 70% of people with ASD exhibit anomalies in sensory perception, Hsieh says, “If larger studies can confirm these results, it is possible that further insight into the peripheral nervous system could help us understand how this disorder develops and potentially light the way for treating these distressing sensory symptoms that most people with autism experience.”


Citations

“Small fiber pathology in autism and clinical implications,” Yi-Ling Chien, Chi-Chao Chao, Shao-Wei Wu, Hsueh-Wen Hsueh, Yen-Nan Chiu, Wen-Che Tsai, Susan Shur-Fen Gau, and Sung-Tsang Hsieh, Neurology, October 14, 2020 (online). Address: Susan Shur-Fen Gau, Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan, [email protected]

—and— 

“Nerves that sense touch may play role in autism,” Science Daily, October 14, 2020.