Sunday, July 22, 2012

Autism Link with Rainy Climates Points Squarely at Vitamin D Deficiency

Rates of autism are higher within the rainiest counties of three different states, in an analysis conducted by researchers from Cornell University and published in the Archives of Pediatric and Adolescent Medicine, suggesting that environmentally related factors such as vitamin D deficiency might play a role in the disorder. "If you look at the autism literature now, they're much more open to an environmental trigger," lead researcher Michael Waldman said. Researchers conducted a new and "more refined" analysis of a controversial 2006 study, released as a working paper of the National Bureau of Economic Research. Both studies compared autism rates and other variables between the different counties of three states: Washington, Oregon and California. The original paper, "Does Television Cause Autism?," found higher rates of autism in counties where a higher proportion of homes subscribed to cable television services, as well as counties with higher yearly rates of precipitation. The current re-analysis confirmed the precipitation results. The new study and the 2006 original are not the only ones to point to a link between autism and rainier weather. In 2003, a survey by the U.S. Department of Education found the highest autism rates in northern states such as Indiana, Maine, Massachusetts, Minnesota and Oregon, and the lowest rates in dry or sunny states such as Colorado, Mississippi, New Mexico, Oklahoma or Tennessee. This led some researchers to wonder if autism might not be caused, at least in part, by vitamin D deficiency. Vitamin D is synthesized by the body upon exposure to the ultraviolet radiation from sunlight, and deficiency is especially widespread in cloudy climates far from the equator. Other potential autism risk factors associated with higher precipitation include increased television watching, more exposure to household chemicals, or direct exposure to pollutants carried by the rain or snow itself. In an accompanying editorial, Noel Weiss of the University of Washington called on scientists to conduct further research on the environmental triggers suggested by the Cornell study. Source -

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