Boys With Regressive Autism, but Not Early Onset Autism, Have Larger Brains Than Age-Matched Healthy Counterparts, Study Finds

In the largest study of brain development in preschoolers with autism to date, UC Davis MIND Institute researchers have found that 3-year-old boys with regressive autism, but not early onset autism, have larger brains than their healthy counterparts.

The study is published online in theProceedings of the National Academy of Sciences Early Edition. It was led by Christine Wu Nordahl, a researcher at the UC Davis MIND Institute and an assistant professor in the Department of Psychiatry and Behavioral Sciences and David G. Amaral, Beneto Foundation Chair, MIND Institute Research Director and University of California Distinguished Professor in the Department of Psychiatry and Behavioral Sciences.

"The finding that boys with regressive autism show a different form of neuropathology than boys with early onset autism is novel," Nordahl said. "Moreover, when we evaluated girls with autism separately from boys, we found that no girls -- regardless of whether they had early onset or regressive autism --had abnormal brain growth."

Brain enlargement has been observed in previous studies of autism. However, prior to this study, little was known about how many and which children with autism have abnormally large brains.

"This adds to the growing evidence that there are multiple biological subtypes of autism, with different neurobiological underpinnings," Amaral said.

Autism is a neurodevelopmental disorder whose symptoms include deficits in language and social interaction and communication. The condition affects 1 in 110 children born today, according to the U.S. Centers for Disease Control and Prevention. It is diagnosed more frequently in male children than female children -- at a ratio of 4 to 1.

The current study is one of the first published from data collected by the UC Davis MIND Institute Autism Phenome Project (APP). The project's goal is to recruit and enroll as many very young children as possible in order to collect sufficient biological and behavioral information to characterize different autism subgroups and to explore different neural, immunologic, and genetic signatures of autism.

Read more: http://www.sciencedaily.com/releases/2011/11/111128152410