New research states autism ‘may be caused by nerve problems in the legs, arms and hands’ rather than just abnormal brain development
Scientists genetically engineered mice for the experiment and measured how they reacted to touch
NEW research suggests some symptoms of autism may be caused by defects in the sensory nerves that run through the body.
People with Autism spectrum disorder (ASD) are sensitive to touch, have difficulties with social interaction and can suffer from anxiety.
Typically, the disorder is thought to be caused by an abnormality in brain development.
However, Harvard Medical school experts believe sensory nerves - defective due to gene mutations – could also be responsible.
Any physical contact is felt at an exaggerated level, which can lead to anxiety and behavioural problems.
The researchers looked at the effect of these gene mutations and tried to detect if the peripheral sensory nerves – rather than the brain – could trigger symptoms of ASD.
They genetically engineered mice with mutations found only in their peripheral sensory never cells.
They measured how the mice reacted to touch and tested whether they could differentiate between objects with different textures.
Mice with gene mutations in their sensory never cells displayed heightened sensitivity to touch and couldn’t distinguish between different textures.
The transmission of impulses between the nerves in the skin and spinal cord were also abnormal.
Next, they examined the mice’s anxiety levels and social skills, observing whether they avoided being out in the open.
Surprisingly, the animals bred to have ASD gene mutations showed heightened anxiety and were less willing to interact with other mice.
Professor Ginty said his work shows mutations in the sensory nerve cells contributes to problems with behaviour.
This is a concept which has not been seen before, he added.
How these problems with touch leads to anxiety and social problems is not currently clear.
Dr Lauren Orefice, a postdoctoral fellow in Professor Ginty’s lab, said the “volume “ swich on these nerve cells was turned all the way up, causing the animals to feel touch at an exaggerated level.
She added: “We think it works the same way in humans with ASD.
“The sense of touch is important for mediating our interactions with the environment, and for how we navigate the world around us.
“An abnormal sense of touch is only one aspect of ASD, and while we don’t claim this explains all the symptoms seen in people, defects in touch processing may help to explain some of the behaviours observed in patients with ASD.”
The investigators are now looking for approaches that might reduce this sensitivity.
The findings were published in the journal Cell.
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