Brain Anatomy Could Point to Autism

May 5 -- MONDAY, May 4 (HealthDay News) -- Autistic toddlers seem more likely to have an enlarged amygdala, a brain area linked with facial recognition and emotions, University of North Carolina researchers report.

This brain abnormality appears to be tied to the ability to share attention and experiences with others, the team said.

"This study adds clarification to a potential fundamental brain mechanism underlying social deficits in autism. It provides potential insights into how this behavior develops," said lead researcher Dr. Joseph Piven, a professor of psychiatry.

"We found enlargement of the amygdala in very young children with autism at 2 years of age, and followed up again at age 4. The enlargement was stable over the 2- to 4-year-old time interval," he said.

The amygdala is a structure that has previously been implicated in social and emotional perception and in autism, Piven said.

"We also found that this enlargement was related to something called joint attention, or the ability of a young child to take cues from an adult about where to look in the visual field, for example, at an object of interest," he said.

This ability develops in a narrow window, between 9 and 15 months, and is thought to be a fundamental deficit in autistic individuals that predicts poor outcomes in social behavior and language, Piven explained.

"In another study, we have shown evidence that the brain in autism is normal in size until the end of the first year of life, at which time it overgrows," he said.

"Understanding the pattern of very early brain changes in autism and their relationship to particular behaviors could lead to enhanced early detection and could direct us to early interventions for these brain and behavior changes," Piven said.

The report is published in the May issue of the Archives of General Psychiatry.

For the study, Piven's team conducted MRI scans of 50 autistic children and 33 children without the condition. The children had brain scans and testing of certain behavioral features of autism at 2 and 4.