May 5, 2009

Brain abnormalities in autistic toddlers

Autistic toddlers appear more likely to have an enlarged amygdala, a brain area associated with processing faces and emotion, U.S. researchers suggest.

Matthew W. Mosconi and colleagues at the University of North Carolina at Chapel Hill say 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.

The researchers conducted a magnetic resonance imaging study involving 50 autistic children and 33 controls. The 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, Mosconi said.

The study, published in the Archives of General Psychiatry, found compared to the controls, the children with autism were more likely to have amygdala enlargement both at age 2 and age 4.

These findings suggest that, consistent with a previous report of head circumference growth rates in autism and studies of amygdala volume in childhood, amygdala growth trajectories are accelerated before age 2 years in autism and remain enlarged during early childhood, the authors say in a statement.