Could sibling brain activity provide autism clue?

Researchers found similar brain activity patterns among children with autism and their non-autistic siblings. Flickr/Vintage Lulu
Scientists have discovered similarities in the brain activity patterns of autistic teens and their non-autistic siblings, hinting at a new ‘biomarker’ for autism risk within families.

In a paper published in the journal Translational Psychiatry, University of Cambridge researchers report that, when shown pictures of emotional facial expressions, people with autism and their non-autistic siblings had reduced activity in the part of the brain associated with empathy.

By contrast, people with no family history of autism did not have reduced activity in that part of the brain.

The experiment involved 40 people aged 12-18 years with an autism spectrum disorder, diagnosed as either autism or Asperger syndrome and 40 of their unaffected siblings.

Another 40 teenagers with normal development also participated as a control group.

The subjects were shown happy, fearful and neutral expressions while their brain activity patterns were monitored via functional magnetic resonance imaging (fMRI).

“Strikingly, the functional magnetic resonance imaging (fMRI) response to happy versus neutral faces was significantly reduced in unaffected siblings compared with controls within a number of brain areas implicated in empathy and face processing,” the authors wrote.

“These results demonstrate that the fMRI response to facial expression of emotion is a candidate neuroimaging endophenotype (biomarker) for autism, and may offer far-reaching insights into the etiology (cause) of autism.”

However, the experiment design may have focused too heavily on the reading of facial expressions, said Associate Professor Mark Stokes, an autism specialist from Deakin University’s School of Psychology.

“We know empathy is an issue for some persons with autism, but it is not an issue for all persons with autism by any means, nor is the reading of faces the definitive issue in autism,” he said.

He also pointed out that people with autism share many more genes with their siblings than they would with an unaffected person in the control group.

“Thus, the similarity in brain function is more likely to be a result of similar genes that have nothing to do with autism,” he said.