Scientists say they have identified a distinct pattern of brain activity that may indicate whether a person is genetically predisposed to autism.
Children with autism and their siblings who do not have the disorder displayed a similar pattern of brain activity when viewing videos of people engaging in highly social activities, such as playing the child's game patty-cake, according to a new study. Children with autism , who experience social deficits , are known to have impaired perceptions of these videos, but the study showed their brothers and sisters also had reduced activity in certain brain regions, when compared with a group of typically developing children.
The researchers also found that the siblings of children with autism exhibited another brain-activity pattern — distinct from the kids with autism and from the other typically developing children — that may indicate they are compensating for a predisposition to autism, the researchers said. The pattern may prevent them from developing the full-blown disorder.
These compensatory regions might be the target for future autism therapies, the researcher said.
"It may be that training up social-perception abilities, and focusing on the compensatory regions could improve social perception and cognition in children with autism," said study researcher Martha Kaiser, a postdoctoral researcher at Yale School of Medicine.
Kaiser and her colleagues scanned the brains of 62 children ages 4 to 17 using functional magnetic resonance imaging (fMRI). Twenty-five had autism, 20 others were typically developing children who had siblings with autism, and 17 were typically developing children without siblings with autism.
The children in all three categories watched "point-light displays" on video — videotapes of people moving around in the dark, with lights attached to their joints. Studies have shown that the behavior and brain activity of people who have autism, regardless of their age, differ from those of other people in response to these videos.
Using fMRI, the researchers observed brain activity in regions involved in social perception and cognition while the children watched the videos.
Only the children with autism showed reduced activity in some brain regions — a unique pattern that may be a result of developing and living with autism, the researchers said.
Other brain regions showed reduced activity in both the children with autism and their siblings. This pattern may hint at an underlying genetic risk of autism at work in the brain, the researchers said.
"We were able to still find something unique about being an unaffected sibling" of someone with autism, said Kevin Pelphrey, also of Yale, who led the study.
The siblings of children with autism also displayed uniquely heightened activity in some brain regions — the proposed compensatory regions.
Future diagnosis and therapies
If the researchers can replicate their results in another study, these patterns of brain activity may help diagnose and treat autism in the future, Kaiser said.
The patterns of brain activity shared between the children with autism and their siblings also may help researchers look for genes that play a role in autism and influence specific brain regions, Pelphrey said.
"The study is extremely innovative, and provides remarkable new clues to the origins of autism — which, if replicated, constitute major new inroads to understanding the development of autism," said Dr. John Constantino, director of child and adolescent psychiatry at Washington University in St. Louis, who studies autism and was not involved in the new work. He observed that the study was particularly well-designed to look for differences between the three groups.
"To link a suspected neuropsychological abnormality — i.e., in processing of biological motion — with both genetic susceptibility and specific brain activation abnormalities is nearly unprecedented, and takes full advantage of recent leads from genetics, psychology and neuroscience," he said.
The study is to be published this week in the journal Proceedings of the National Academy of Sciences.