Children in California, Oregon and Washington are more likely to develop autism if they lived in counties with higher levels of annual rainfall, suggesting that something about wet weather might trigger the disorder, according to a study released Monday.
Among possible explanations: Bad weather could lead to more TV and video viewing, which in very young children has been linked to language-development issues. Or staying indoors could cause a deficiency of vitamin D, the “sunshine vitamin” increasingly found to play a vital role in health.
“If it rains a lot, children spend more time inside,” said Sean Nicholson, a Cornell University policy analyst and an author of the study in the Archives of Pediatrics & Adolescent Medicine. “It could be that there was something positive outside that they’re getting less of, or there’s something in the indoor environment that’s harmful.”
The study and accompanying editorial stressed the association between autism and rain has not been clinically proved and that possible explanations need more testing.
“This is iffy, tentative stuff, not because the researchers aren’t competent but because it’s a difficult problem to study,” said Noel Weiss, a University of Washington epidemiologist who wrote the editorial. “The hope is that by reading this article, other researchers will look into this question.”
Federal health officials estimate that autism affects 1 in 150 U.S. children, a number that has risen drastically in the past three decades from roughly 1 in 2,500. Autism is a neurodevelopmental disorder that impairs communication and socialization and is often marked by repetitive behaviors such as rocking.
