Brain scan study illuminates family autism risk
12 July 2011
New research carried out by the Medical Research Council (MRC) and the University of Cambridge has revealed that the brain scans of brothers and sisters of teenagers with autism show reduced activity in brain areas associated with empathy, similar to their sibling with autism. This research may help us to identify the genetic causes of predispositions for autism and understand why it can affect family members so differently.
The new study, funded by the MRC and carried out at the Autism Research Centre, University of Cambridge and the MRC’s Cognition and Brain Sciences Unit, is one of the largest functional MRI (fMRI) brain scanning studies of autism ever conducted. The study involved 40 teenagers affected by autism, 40 siblings of these teens and 40 teenagers with no family history of autism. The 120 participants were given brain scans while viewing a series of photographs of faces which were either neutral or expressing an emotion such as happiness. By comparing the brain's activity when viewing a happy verses a neutral face, the scientists were able to observe the areas within the brain that respond to this emotion.
Previous research has found that people with autism often struggle to read people’s emotions. The new study has revealed for the first time that although the siblings taking part did not have a diagnosis of autism, they still showed decreased activity in various areas of the brain, which indicate their ability to empathise, understand others’ emotions and process information from facial expressions. Teenagers with no family history of autism did not display any indicators of impaired brain activity in any of the areas tested.
Dr Michael Spencer, who led the study at the University of Cambridge, said:
“The findings provide a springboard to investigate what specific genes are associated with this brain activity marker. The brain's response to facial emotion could be a fundamental building block in causing autism and its associated difficulties. It is likely that in the sibling who develops autism, additional, as yet unknown steps – such as further genetic, brain structure or function differences – take place to cause autism.”
In a family where one child already has autism, the chances of a subsequent child developing autism are at least 20 times higher than in the general population, although specific mechanisms for the increased risk have been unclear. The new study’s findings further demonstrate that siblings can share genes which will influence their brain activity patterns and their chances of being autistic. These results will help researchers to identify which specific genes may be responsible for the increased risk.
Professor Chris Kennard, chair of the Medical Research Council funding board for the research, said:
“This is the first time that a brain response to different human facial emotions has been shown to have similarities in people with autism and their unaffected brothers and sisters. Innovative research like this improves our understanding of how autism is passed through generations affecting some and not others. This is an important contribution to the Medical Research Council’s strategy to use sophisticated techniques to uncover underpinning brain processes, and to target treatments to the spectrum of complex disorders such as autism.”
The paper "A novel functional brain imaging endophenotype of autism: the neural response to facial expression of emotion" by MD Spencer, RJ Holt, LR Chura, J Suckling, AJ Calder, ET Bullmore and S Baron-Cohen is published in the July issue of Translational Psychiatry.
