Wednesday, July 6, 2011

Environment May Play Bigger Role in Origins of Autism

For decades, researchers have assumed that autism spectrum disorders were largely due to genetic factors, based on a 1977 study of twin pairs.

A new study in the Archives of General Psychiatry (published online July 4) looked at 192 pairs of twins born from 1987 to 2004 in which at least one child had an autism spectrum disorder to assess the relative roles of genetics and environment in risk for those disorders.

“Environmental factors common to twins explain about 55 percent of the liability to autism,” wrote Joachim Hallmayer, M.D., of the Department of Psychiatry at Stanford University School of Medicine, and colleagues. “Although genetic factors also play an important role, they are of substantially lower magnitude than estimates from prior twin studies of autism.” Environmental risk factors during pregnancy or in the first year of life might  include parental age, low birth weight, multiple births, and maternal infections during pregnancy, they wrote.

Read more about autism prevalence in Psychiatric News at


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