Rain may hike increase in Autism

Rain may heighten risk of autism

But U.S. researchers don't know why the wet weather could be a factor

Jack Keating, The Province; with a file from Reuters

Published: Wednesday, November 05, 2008 - http://www.canada.com/theprovince/news/story.html?id=c7ec619a-d40a-41d3-a3a0-6e687ee5b1f1

Wet and rainy weather may increase the risk of developing autism in children, but it is unclear why, U.S. researchers reported yesterday.

"Autism prevalence rates for school-aged children in California, Oregon and Washington in 2005 were positively related to the amount of precipitation these counties received from 1987 through 2001," Prof. Michael Waldman of Cornell University wrote in the November issue of Archives of Pediatric & Adolescent Medicine.

A Vancouver doctor who specializes in autism said the findings are no cause for alarm even given B.C.'s wet weather, and should be used, if at all, primarily in stimulating further research into autism's causes.

Max Harding, 5, who has moderate autism, and his mom, Kim, walk Forest, a two-year-old yellow Lab, recently. Forest is the first autism service dog trained by B.C. Guide Dog Services. Wet and rainy weather may increase the risk of developing autism in children, but it is unclear why, U.S. researchers reported yesterday.

Max Harding, 5, who has moderate autism, and his mom, Kim, walk Forest, a two-year-old yellow Lab, recently. Forest is the first autism service dog trained by B.C. Guide Dog Services. Wet and rainy weather may increase the risk of developing autism in children, but it is unclear why, U.S. researchers reported yesterday.

Les Bazso file photo - The Province

He urged caution in interpreting the preliminary results.

"I don't think this is cause for widespread alarm or people deciding they need to move to a drier climate," said Dr. Steve Wellington, clinical director of the B.C. Autism Assessment Network.

"I would not want anyone to take that away from what is really a very preliminary and initial result."

The findings were based on autism rates from state and county agencies for children born in California, Oregon and Washington. The researchers paired them with daily precipitation reports.

Counties with more than 685 millimetres of precipitation annually tended to be the same areas with higher-than-average autism rates, while those with less than than 558 mm a year of rain tended to have lower-than-median rates, the researchers found.

Metro Vancouver's average annual rainfall is 1,117 mm.

"The relationship of rain in of itself has so many possible interpretations," said Wellington. "I think it's going to need some time for the research community to sort of sift through that."

It is not clear what causes autism. The symptoms range from severe social avoidance to repetitive behaviours and sometimes mental retardation.

The majority of good research over the past five to seven years has increasingly shown links that support a genetic component to the development of autism, said Wellington, a developmental pediatrician with Sunnyhill Health Centre For Children.

The U.S. researchers speculated that in rainy climates, infants and toddlers are kept indoors, perhaps in front of the TV. That, they said, might cause brain changes or the children may breathe more harmful chemicals while indoors.

Vitamin D deficiency caused by insufficient time in the sun might also be a trigger for autism, the researchers said.

"Finally, there is also the possibility that precipitation itself is more directly involved," the researchers wrote.

"Perhaps a chemical or chemicals in the upper atmosphere are transported to the surface through rain or snow."

The researchers cautioned that their findings were not definitive and that further research is needed.

Dr. Michael Fitzpatrick, a London physician who wrote Defeating Autism: A Damaging Delusion, doubted the report's findings, noting that autism diagnoses are on the rise in all climates.

"In recent years autism has been blamed on everything from discarded iPod batteries to mercury from Chinese power stations, from antenatal ultrasound scans to post-natal cord clamping, from diet to vaccines," he said.

jkeating@theprovince.com

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