Rainfall, Autism May Be Linked

Children Living In High-Precipitation Areas More Likely To Have Autism, Study Shows

(WebMD)  Children living in areas of high precipitation may be more likely to have autism, according to a new study, but the researchers caution that the finding of a rainfall-autism link is preliminary.

The finding may have nothing to do with the rainfall or snow itself, they say, but rather factors associated with the precipitation, such as the need to stay indoors more.

"Our results suggest there is an environmental trigger associated with precipitation," says Michael Waldman, PhD, the study's lead author and the director of the Institute for the Advancement of Economics at Cornell University in Ithaca, N.Y.

"I strongly believe it's not the precipitation itself," he tells WebMD. "My sense is, if truly there is an environmental trigger, my guess is it is one of the factors related to indoor activity." On that list: chemical exposure to indoor substances such as cleaning products, TV viewing, and vitamin D deficiency from too little sunlight.

Autism: The Back Story

In the past 30 years, the rates of autism have increased from about one in 2,500 children to one in 150. Although some of the increase is attributed to a broadened definition of autism, not all can be linked to that, experts say. In the past few years, more researchers have been exploring the possibility that the disorder involves an interaction of genetics and environmental factors, Waldman says.

Autism spectrum disorders refer to autism and a broader range of developmental disorders marked by social impairment, language or communication difficulties, and unusual behavior, such as discomfort with human contact.

Precipitation-Autism Link: Study Details

Two years ago, Waldman and his colleagues had zeroed in on the effects of television viewing as a risk factor for autism, says Sean Nicholson, PhD, associate professor of policy analysis and management at Cornell and a co-author of the study, published in the November issue of Archives of Pediatrics & Adolescent Medicine.

"And the more we worked on it, the more we said, 'Let's take a step back,'" Nicholson says.

They decided to look at precipitation, selecting to focus on California, Washington, and Oregon. They obtained autism prevalence rates in 2005 for children born in those three states between 1987 and 1999 and calculated average annual precipitation by county from 1987 to 2001. They also computed the autism rates in relation to the average annual precipitation in the counties when the children were younger than age 3.

"Counties that received relatively large amounts of precipitation had a relatively high rate of autism," Nicholson tells WebMD. "Counties in Oregon and Washington west of the Cascades receive four times as much precipitation as counties east of the Cascades, and have an autism rate that is twice as high," he says.

Put another way: "If there were no rain, the autism rate would be a third lower according to our analysis," Nicholson says.

The amount of precipitation children were exposed to before age 3 was also positively associated with autism rates, the researchers found. The age at diagnosis varies but is sometimes made as early as 18 months.

The team also looked at each county over time, taking into account different precipitation levels from different years, he says. This was done to rule out the effect of other factors, such as differences in the quality of the health care systems from one county to another.

The relationship between precipitation and autism held, he says.

Precipitation-Autism Link: Study Interpretations

The results do raise the possibility that an environmental trigger for autism may be linked to precipitation, perhaps affecting children who are genetically vulnerable, the researchers say.

"It could be the rain itself," Nicholson says. For instance, chemicals in the upper atmosphere may be transported to the surface by the rain, the researchers speculate.

Or, as Waldman suggests, the amount of time children spend indoors when they live in a heavy rainfall area might increase their exposure to potentially harmful chemicals, such as those from cleaning products. Being indoors could decrease their sunshine exposure, thus reducing vitamin D levels.

Precipitation-Autism Link: Caveats

The observation about precipitation and autism rates may not lead to any insights at all on the causes of the disorder, writes Noel Weiss, MD, DrPh, a professor of epidemiology at the University of Washington, Seattle, in an editorial accompanying the study.

"These results are really [meant] to alert other investigators to the hypothesis," he tells WebMD.

The findings, he adds, should not be taken as a reason to move to a drier climate or a reason to ban television viewing.

Take-Home Advice

The results are not definitive evidence of a precipitation-autism link, as Waldman, Nicholson, and their colleagues acknowledge in the report.

"But the results are consistent with the hypothesis, and, therefore, further research focused on establishing whether such a trigger exists and on identifying it is warranted," they conclude.

[grammawhamma]

Just read the headlines of the WebMD articles. Over 90% have the words "May Be" in the headline.

What does that tell you?

[kerrjac2]

Does the potential role of mold seem completely obvious to anyone else?

I don''t understand how you can talk about rainy places & health, & mold still doesn''t come up. Changes in the norm for building insulation & circulation underlie why mold is becoming more of an issue. But even aside from somewhat controversial arguments that mold is detrimental to health, it''s at the very least a defining characteristic of wet places...moreso than children staying inside huffing household cleaning products.

[gaye5]

The article says....but the researchers caution that the finding of a rainfall-autism link is preliminary.

What a lot of rot, proves we cannot believe anything these stupid researchers say...
My huaband and I were born on the the wettest mountain in NZ and in our very large school all we had was one child with asthma..
Then my husband became a principal and I became a nurse we never had any such cases.. Of course my husband being the principal would more than likely know of any siblings who had problems or were put away..
When are people going to wake up to the fact that Dr''s and pharmecutical drugs are the fourth cause of death in America..

[spadeisspade]

I know what it is!!! It''s global warming. See...global warming started becoming an issue around the time autism rates started climbing.

Or wait! It''s Walmart! Walmart started growing 30 years ago.

Oh, wait. I got it. It''s urban sprawl!

Seriously, though; did they do any studies with kids who might not ever get out of the house because their parents don''t take them outside?

[puzzler125]

When children are indoors far more they are exposed to greater amounts of vapors from paneling, paint, cleaning products and other chemicals. One day I believe somehow will figure out the answer...

[maritzaapont]

I agree that if it was rainfall then it wouldve been evidence that it caused autism 30 years ago. My son is two and was diagnosed with autism. I honestly believe with all the research I have been doing that it is linked with low immune systems and how the body reacts to different environmental agents with low immune systems. These poor kids don''t have strong immune systems to fight off certain toxins that enter their body with the vaccines they receive. I don''t believe its the vaccines that cause autism I believe its how the body cannot fight correctly with the viruses that given via vaccine to our children. The cells are dead and therefore our children suffer even more when the vaccines are given. How can we help our kids? There is no way except by making sure our children eat healthy diets and by helping their immune system function properly. Holistic approach is the way to go. As far as this rainfall research. I don''t believe it has anything to do with my child having autism. Thanks for listening.

Maritza in Ohio

[kerrjac2]

It''s mold!

[deepperppl]

One of the reasons studies like this help is - if we finally figure out what triggers the Autism, we can avoid those things, test how they interact and finally come to a cure. (Well, a medication, knowing most studies are usually funded by pharmaceutical companies.) Autism is very real to someone like me - my son was diagnosed at age 5 (finally.. after searching for 4 years), and we were dirt poor. Kinda ruins that hypothesis, saying it''s a diagnosis made to bilk the parents of hard-earned money. It would help if people thought before they spoke - claiming it''s a sham diagnosis just to get money out of the parents, is just cruel. Parents of Autistic kids are only trying to help their child become as normal as possible. Until you have an Autistic child, you will never understand exactly how devastating it is and how much this kind of research could finally benefit others in the future. It''s a small step, but a step nonetheless. I wouldn''t wish an Autistic child on anyone, even the ignorant who put down things they could never understand.

[kenhamlett]

God have mercy on me for what I am thinking about this article.
To skip the pages I could write on the waste of resources, the fallacy of the definition of autism and the inability of those few that may actually have a need to get effective help, I will simply offer a couple of alternative theories.
I believe that the diagnosis of autism is directly related to the amount of money that can be tapped to "treat" the victims.
I believe I can find a stronger correlation to show that snow and broken bones are related.
I believe the researchers who were involved with this research can be shown to be incompetent.

Could someone send me a few million dollars so I can research these theories as a valuable contribution to the knowledge base of mankind.

[lilbeards1]

Millions of dollars being poured into Autism research, and THIS is what they come up with??? What a crock!

[doggiemom1]

This is one of the craziest things I have ever heard. 30 years ago we did not have autism at the rate we have today. Guess it must not have rained anywhere back then.