Toddlers with autism appear more likely to have an enlarged amygdala, a brain area associated with numerous functions, including the processing of faces and emotion, according to a report in the May issue of Archives of General Psychiatry.
In addition, this brain abnormality appears to be associated with the ability to share attention with others, a fundamental ability thought to predict later social and language function in children with autism.
"Autism is a complex neurodevelopmental disorder likely involving multiple brain systems," the authors write as background information in the article. "Converging evidence from magnetic resonance imaging, head circumference and postmortem studies suggests that brain volume enlargement is a characteristic feature of autism, with its onset most likely occurring in the latter part of the first year of life." Based both on its function and studies of changes in its structure, the amygdala has been identified as a brain area potentially associated with autism.
Matthew W. Mosconi, Ph.D., and colleagues at the University of North Carolina at Chapel Hill conducted a magnetic resonance imaging study involving 50 autistic children and 33 control children. Participating children underwent brain scans along with testing of certain behavioral features of autism at ages 2 and 4. This included a measure of joint attention, which involves following another person's gaze to initiate a shared experience.