That finding by researchers at the University of North Carolina-Chapel Hill's Neurodevelopmental Disorders Research Center supported concurrent research that has found brain overgrowth in autistic children as young as 2 years.

The lead investigator of the study, Dr. Joseph Piven, said behavioral studies of infants at high risk for autism suggest the onset of most behavioral symptoms defining autism also occur at about age one.

"One reason these findings are important is because early post-natal onset raises the possibility that there may be a window for early treatment and prevention that could be identified by future studies," Piven said.

Piven cautioned, however, that while the study seems to suggest a link between brain overgrowth and autism, there are many variants of autism among children, so the ways in which autistic children develop and are affected by brain growth can vary greatly.

The study was presented in Boca Raton, Fla., during this week's annual meeting of the American College of Neuropsychopharmacology.