Autism linked with rainfall in study 
LCD
16 y
4,148
† Cross †
Lugol’s Iodine Free S&H
J.Crow’s® Lugol’s Iodine Solution. Restore lost reserves.
Real WEIGHT LOSS
Regenerate your digestive system and organs. Speed up your metabolism...
Original Dr. Hulda Clark
Hulda Clark Cleanses
Autism linked with rainfall in study
Tue Nov 4, 10:30 am ET
WASHINGTON (Reuters) – Children who live in the U.S. Northwest's wettest counties are more likely to have autism, but it is unclear why, U.S. researchers reported on Tuesday.
Michael Waldman of Cornell University and colleagues were searching for an environmental link with autism, a condition characterized by learning and social disabilities.
http://news.yahoo.com/s/nm/20081104/sc_nm/us_autism_rain
They got autism rates from state and county agencies for children born in California, Oregon and Washington between 1987 and 1999 and plotted them against daily precipitation reports.
"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," they wrote in the Archives of Pediatrics & Adolescent Medicine.
Dr. Michael Fitzpatrick, a London physician who wrote "Defeating Autism: A Damaging Delusion", expressed doubt, noting that autism diagnoses are on the rise in all climates.
No one know what causes autism, whose symptoms range from severe social avoidance to repetitive behaviors and sometimes profound mental retardation.
The U.S. Centers for Disease Control and Prevention estimates that about one in every 150 children has autism or a related disorder such as Asperger's Syndrome. Rates in many countries have been rising, although that may be partly due to increased reporting and diagnosis of the condition.
Doctors agree there is a genetic component to autism. They also theorize that something in the environment and possibly conditions in the womb can trigger the condition.
The researchers said their study supports this idea.
Perhaps infants and toddlers are kept are kept indoors in front of the TV more in rainy climates, and that somehow causes brain changes, they said. Or perhaps they breathe in more harmful chemicals while indoors.
Vitamin D deficiency caused by insufficient time in the sun might also be a trigger, they said.
"Finally, there is also the possibility that precipitation itself is more directly involved," they wrote. Perhaps a chemical or chemicals in the upper atmosphere are transported to the surface through rain or snow.
"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," Fitzpatrick said in a statement.
The U.S. Centers for Disease Control and Prevention has launched a long-term study to find the causes of autism and other childhood conditions.
(Reporting by Maggie Fox; Editing by Michael Kahn and Alan Elsner)
- Link Between Precipitation and Autis... LCD
16 y
4,809
This is a reply to # 1,293,643Rainman - Link Between Precipitation and Autism
Published by Steven Novella under Neuroscience/Mental Health
Comments: 7
A new study published in the Archives of Pediatrics and Adolescent Medicine shows a positive correlation between counties in California, Oregon, and Washington with greater precipitation and a higher incidence of autism. While the results of this study are interesting, it needs to be put into proper context. Also of note, the authors had presented early results from this data previously.
http://www.sciencebasedmedicine.org/?p=275
Correlation is not Causation
This type of study is a correlational study, which means it asks whether or not there is a statistical correlation between two variables - in this case the rate of autism and the amount of precipitation. This type of data is extremely useful to medical science, but it has known limitations, which can be summarized by the statement that correlation is not causation.
I often see this principle used to dismiss correlation data entirely, but that is not the correct approach. Correlation, rather, needs to be considered in the proper context. When A correlates with B there are various possible interpretations: the correlation is a statistical fluke (coincidence); A causes B, B causes A, or both A and B correlate with another variable C, and there can be a variety of causal relationships among the three (or more) variables which would cause A to track with B.
Therefore, finding a correlation is a way to generate several hypotheses which can then be tested by further observations or research. That, in my opinion, is the best way to view correlational data - as a beginning step to help generate hypothesis. But they should not be used to reach firm conclusions.
It should also be noted that further correlations can be used to test various causal theories, and if multiple correlations all triangulate to a single causal hypothesis that can lead to a fairly confident conclusion - even in the absence of other evidence. For example, smoking correlates with certain types of lung cancer. There are no prospective studies in humans to establish that smoking causes lung cancer, but we can be confident that it does because the correlation holds up no matter how you choose to look at it. If smoking causes cancer (as opposed to other causal hypotheses stemming from the correlation) then we predict that increased duration of smoking increases risk of lung cancer, that stopping smoking decreases risk, that smoking unfiltered is more risky than filtered, etc. Each of the predictions turns out to be true, supporting the smoking causes lung cancer hypothesis.
Rain and Autism
I was immediately interested in how the authors of this study came by the notion that rain might correlate with autism rates. In their older publication they mention that they thought of it as a way to test the hypothesis that TV watching may be an environmental trigger for autism, and that increased precipitation correlates with greater TV watching. In their most recent publication they explore various other causal hypotheses.
For example, they discuss that increased rain leads to more time spent indoors. While this may lead to increased TV watching, it also leads to an increase in all indoor activities. It also leads to increased exposure to the indoor environment, and decreased exposure to the outdoor environment. Therefore there may be some indoor trigger or outdoor protective element.
The rain itself may be involved. Increased rain may increase exposure to atmospheric toxins.
The authors also raise the possibility that increased precipitation correlates with decrease sun exposure, which could lead to relative Vitamin D deficiency, which is the actual trigger for autism. I actually find this the most plausible scenario. Relative vitamin D deficiency has been linked recently to increased risk of a variety of neurological disorders, and has lead to an increase in the recommended daily allowance of Vitamin D for children.
But what the study does not discuss are those causal hypotheses that no one has yet considered (obviously because no one has considered them). This is always the primary weakness of pure correlation - there are so many variables that it is nearly impossible to anticipate them all.
Here is an example from an unrelated field. The research on the possible protective effects of alcohol and heart disease has been largely epidemiological (i.e. correlation). Many studies showed that those who drink a little every day are healthier than those who do not drink at all. It was not considered for many years after this data started to come out, however, that the group that does not drink at all contains ex-drinkers, who are unhealthy as a consequence of their prior alcohol abuse. That may seem like an obvious point now, but it was missed for a long time.
It therefore seems possible, even likely, that there can be a complex causal relationship hiding in this apparent correlation between rain and autism.
We won’t know until further studies are done. The authors of this study concluded:
These results are consistent with the existence of an environmental trigger for autism among genetically vulnerable children that is positively associated with precipitation. Further studies focused on establishing whether such a trigger exists and identifying the specific trigger are warranted.
This is the exactly correct way to word this conclusion - the results are consistent with an environment trigger (but do not prove that one exists), and the results warrant further research (but cannot be used to form reliable conclusions). We can now base predictions on various causal hypotheses stemming from this study as a guide to future research. Something interesting may ultimately come out of this.
Conclusion
Autism remains a poorly understood neurological entity, although it is an area of active research and we have a great deal of information upon which to base our thinking about autism. It is clear that there is a huge genetic component to autism, but it is also probably not a strictly genetic disorder (or, more likely, set of related disorders). While there is no clearly established environmental factor, most such disorders result from an interplay of genetics and environment.
I suspect, however, that the environment of the womb is the dominant environmental factor. Recent research is finding that subtle signs of autism are detectable earlier and earlier in an infants life. The environment of the infant may play a role in expression, but I am not convinced that any post-natal factors trigger autism in children that would otherwise not display any features. This latest study may be providing a clue (if the correlation itself holds up to replication) of a post-natal factor, but right now we are in the wild speculation phase of thinking about these results.
What is clear is that more research is warranted.
http://www.sciencebasedmedicine.org/?p=275
-
Rain man? Or: Does rainfall cause au... LCD
16 y
4,925
This is a reply to # 1,293,643Orac writes:
There were stories in USA Today and MSNBC about a study that concluded that rain causes autism.
From: http://scienceblogs.com/insolence/2008/11/rain_man_or_does_rainfall_cause_aut...
OK, that's not really what the study claims to have found. In fact, the authors were pretty conservative about drawing inferences. However, it did claim to find a correlation between precipitation rates and autism prevalence on the Pacific Coast. The study, published in the November issue of the Archives of Pediatrics and Adolescent Medicine by investigators whose lead author is Dr. Michael Waldman of Cornell University and with collaborations with investigators at Purdue University, and the Children's Hospital of Philadelphia (Paul Offit must be having kiniptions over this) and entitled Autism Prevalence and Precipitation Rates in California, Oregon, and Washington Counties. This study purports to provide evidence that autism prevalence is associated with precipitation. It seems to show just such a correlation, but there are a number of reasons to be very skeptical of the conclusions being drawn from this study, not the least of which are the uses to which mercury militia apologist puts it.
Besides looking at this study as a case study for the truism that correlation does not equal causation, something I want to scream at the top of my lungs when I read a study like this. The other thing that I always look at (and you should too) is the underlying hypothesis of the study:
Similarly, in the recent CDC study of autism prevalence mentioned previously, the highest autism prevalence among the 14 states studied was found in New Jersey, the second-most-northern state in the study, whereas the lowest autism prevalence was found in Alabama, the most southern state in the study.
This pattern suggests a hypothesis: namely, that there is an environmental trigger for autism among genetically vulnerable children that is correlated with bad weather, possibly because the environmental trigger is associated with indoor activities. We explore this hypothesis by empirically investigating the association between autism prevalence and precipitation rates.
This is a tad disingenuous. In reality, this study is an outgrowth of the infamous "television causes autism" study, which started with a dubious hypothesis and ran with it right into the ground. Such a hypothesis is so dubious on a strictly scientific basis, based on what we know about the biology of autism, that it would take an incredible amount of evidence to validate it. The current study resurrects some of the more pithy comments directed at the television study about the strange things that can happen when economists and management faculty apply their methodology to epidemiology and medicine. More importantly, when looking at this study, I ask why: Why do the investigators think that precipitation levels would correlate with autism prevalence? One potential reason is that increased precipitation leads to more time indoors, which could correlate with decreased vitamin D levels, which could be a "trigger" for autism. Fair enough, as far as it goes, but there are quite a few links in the proposed chain of causation, and the more links there are the more tenuous the link between the first link and the last link in the chain. Moreover, there may be other common factors that confound this proposed correlation by being associated with populations living in areas with more precipitation.
But let's get to the study itself.
One thing leaped out at me right away, and that's how the authors correlated precipitation with autism levels. They did not look at raw average precipitation rates. Rather, they invented a variable to correlate to autism rates:
In our tests, we used a relative precipitation variable, which we defined as the difference between the annual precipitation received in a county and the mean precipitation for all counties in the sample. The National Climatic Data Center records daily precipitation at more than 8000 weather stations in the United States. To calculate precipitation in a specific county in a specific year, we first calculated the mean across all weather stations in the county for each day of the year. We added the resulting values from all the days in the year to get the total precipitation, and then calculated mean annual precipitation by county from 1987 through 2001 and for each 3-year interval when the 1987 through 1999 birth cohorts were younger than 3 years. To find relative precipitation levels, we then subtracted the mean annual precipitation level for the counties and years in our sample. The 1987-2001 period spans the dates when children who were school aged in 2005 were younger than 3 years, the time during which autism symptoms emerge and any putative, postnatal factor would be present.
Note that the authors did not correlate autism prevalence directly with raw mean precipitations but instead used a "relative precipitation variable." When I see something like that, I know right away that there was no correlation between raw mean precipitation levels and autism. If there had been, you can rest assured that the authors would not have bothered to go to the trouble to do this little bit of mathematical legerdemain--excuse me, I mean "transformation." This is a general principle of epidemiological studies: If there's a correlation with raw data, then there's no reason to do any sort of mathematical adjustment. Don't get me wrong, though. Such transformations are sometimes valid from a statistical standpoint, but such calculated measurements always give me pause when I see them--especially so when no explanation is given for why they are being used or why the authors consider them more valid or useful than using just the untransformed data for their calculations. Such data massaging always sends up red flags.
There are also multiple other flaws with this study:
Remember the study about industrial mercury I blogged about? You know, the one in which it was claimed that proximity to mercury-emitting power plants correlated with autism prevalence? Remember how I emphasized how important it was to control for urbanicity when looking at autism diagnoses because autism diagnoses correlate with more highly urban areas? Guess what? The authors of the current study, although they tried to correlate for household income, didn't even attempt to control for urbanicity. That alone makes this study highly suspect, at least to me.
Another problem with this study is that it examines only the Pacific Coast, specifically California, Oregon, and Washington. There is no indication that the observations made in this study are generalizable. Sure, you can argue that the study presents a provocative finding, and the authors certainly state that it needs to be followed up on, but it's still not a comprehensive sampling. Moreover, rainfall can vary considerably from year to year, but autism rates do not. Prevalence may be increasing, largely because of widened diagnostic criteria and diagnostic substitution, but it's not an increase superimposed on a curve that widely varies from year to year. How can such a hypothesis account for the fact that rainfall in general is not increasing in most places but autism prevalence is?
Of course, what would be interesting about this study if it holds up is what links high levels of rainfall to increased autism prevalence. One potential factor that could link the two is, as the authors mention, vitamin D. However, there is a paucity of data linking any sort of vitamin D deficiency to autism; a lot more data would be needed. Another potential factor is being indoors and exposure to "indoor toxins." However, there is also a paucity of evidence that anything associated with being indoors correlates with autism. Unfortunately, the authors read far too much into their data:
This study empirically examines the hypothesis that there is an environmental trigger for autism among genetically vulnerable children that is positively associated with precipitation. If there is such an environmental trigger, then the prevalence of autism should be higher in counties that receive abundant precipitation, and especially for birth cohorts that receive above-average precipitation, relative to the county's average amount, when the cohort was younger than 3 years.
Our results support this hypothesis.
No they do not. I guess that's what you get when you have economists doing epidemiology about medicine, you get these sorts of "fast and loose" statements about "genetically vulnerable children" when the data didn't even address the question of genetic susceptibility. It didn't even have the methodology to do so. Now, It's possible there may be a genetic susceptibility to autism that is triggered by an environmental factor or factors, but nothing--I repeat, nothing--in this study supports that hypothesis. Measures of genetic susceptibility were not even a part of the study--or even looked at! To use the words "genetic susceptibility" in the conclusions and to say that this study somehow supports an interaction of genetic susceptibility and environmental factors is just plain incorrect.
The problem with this study, unfortunately, is not just how weak it is, how dubious the hypothesis under study is, or how the authors clearly don't understand the rudiments of genetic susceptibility. Those are all problems, but the big problem with this study is that it's custom made for cranks. In fact, autism crank numero uno David Kirby has already weighed in on--where else?--The Huffington Post:
A new study out of Cornell University says that children growing up in the rainiest or snowiest areas of the country seem to have a higher risk for autism than children living in drier climates.
The authors estimated that removing precipitation as a factor in autism would slice the prevalence of the disorder by 33% to 43%.
Among the possible explanations given were: A lack of vitamin D from a sun-deprived life under the clouds, an increased amount of time spent indoors amid toxic household chemicals, or the presence of dangerous neurotoxins in the precipitation itself, which in turn might trigger a genetic predisposition to ASD.
One of the most omnipresent, growing (and obvious) air-borne neurotoxins in the world to consider, of course, is mercury.
The desperation is palpable here. As I've pointed out before on numerous occasions, epidemiological study after epidemiological study have failed to find even a whisper of a correlation between mercury an autism. Antivaccinationists realize this, too, which is why they have started to grasp at environmental sources of mercury in addition to mercury from vaccines, even to the point of toutting lame studies, such as those of Raymond Palmer. Oh, David Kirby is glib, and he applies his usual twisting of logic, language, and science to try to argue that this study supports his previous fearmongering about mercury, but, let's face it, these days Kirby is a pathetic character, grasping at any mercury-coated straw he can find in search of vindication of his crankery.
Once again, this study tells me one thing, and should tell you the same: Correlation does not equal causation. If you want to know just how dubious this story is, you should be aware that an editorial was published with the study entitled Precipitation and autism: Do these results warrant publication? In the editorial, Dr. Noel Weiss does backflips with logic trying to say that, yes, this study does warrant publication, all the while slamming it as tentative and not particularly convincing. If I were Dr. Weiss, I'd be embarrassed.
It's also depressing to see such dubious studies being provided to cranks like David Kirby as a weapon to use against reason.
Comments
(Sorry - I think a Pharyngulink only works in the other direction. ;))
In addition to the other problems,
In our tests, we used a relative precipitation variable,...
I don't understand how this, without an explicit explanation in the paper, gets through peer review.
I seriously thought someone had forwarded me an article from The Onion when I read about this. I almost choked on my raisin bran.
I also like how they consider county wide precipitation an indicator. Living in the desert southwest, my house gets two to three times the "average" county precipitation due to being positioned in foothills. Does that mean I have to move down into the valley to protect my kids now? Also, they picked states with distinct variable climate zones, coastal strip (also happens to be the urbanized area), coastal mountain range, and dry (rural) interior. I'm sure you get more autism diagnoses in San Francisco than in the farming communities of the Central Valley. But if it's the rain that makes the difference...
The urbanicity problem, or at least something roughly like it in my layman's brain, is exactly the first thing I thought of when I saw this study.
Well, if you substract the mean from a variable, you don't change its correlation with another variable that remains unchanged. Correlations are computed based on variances and covariances, which substract the mean in the first place ( E(X-m)², anyone ?). So I wouldn't call this transformation an attempt to manipulate the data, but just a useless extra step. Or did I miss something ?
You've made me happier by tackling this article this morning! :) And I was already pretty darn happy!
Could mold be the factor?
Christophe:
They're not subtracting the overall mean, but the mean *for that county*.
See also my analysis. I didn't even have to adjust for population density. I couldn't even confirm a naive association.
Annnnnnd I just freaked at the Vitamin D possiblility over on Science-based Medicine. (I can has too much coffee.)
Orac, what do you think of the Vitamin D link? Worth a closer look?
Now didn't that feel better then posting about politics? Good post.
I'm curious how they accounted for the monotonic rise in autism prevalence over the past 15 years when the rainfall for the Pacific coast has fluctuated between wetter than normal and drier than normal at least twice since 1998?
Also, how do the explain that Oregon, even west of the Cascade range, is drier than Washington (and wetter than California) and yet has three times the autism prevalence of either state?
The "average of all the counties in the state" transformation is how they get around "inconvenient truths" like this.
In short, as Orac said, this study is a textbook example of how you can find a statistically significant correlation between any two variables if you squeeze the data hard enough.
Prometheus
I don't understand why nobody is talking about the possibility that it could be that the autistic children are actually *causing* the higher precipitation with their mind-powers! After all, they only found a correlation, the causation could go either way!
In the movie "The Business of Being Born" one of Ricki Lake's sources, Mardsen Wagner, lets loose and links autism to c-sections.
Rose wins the thread!
I do not have access to the full paper, so I have to ask these questions:
Do either Grays Harbor County (Aberdeen, WA) and Clallam County (Forks, WA --- which is where the young adult vampire books, http://www.amazon.com/Twilight-Collectors-Saga-Stephenie-Meyer/dp/0316033413/ , are located) have more autism than either King County (Seattle, WA) or Pierce County (Tacoma, WA)? What are the relative numbers of autism between Ferry County and Kittatas County?
Is the level of autism similar between Yakima, WA and Bend, OR? (both in high deserts with similar populations)
There is a real temperate rain forest on the peninsula because the Olympic Mountains catch all the rain, which is why Seattle is drier than Forks. Also, a good chunk of both Washington and Oregon are deserts. Those also happen to be where there is more agriculture, less industry and smaller cities (Spokane is the largest). Is there a stronger correlation between density and relative wealth between the counties?
Cannell, Autism and Vitamin D, Medical Hypotheses, Vol. 70, Issue 4, 750-759 (2008).
Summary
Any theory of autism's etiology must take into account its strong genetic basis while explaining its striking epidemiology. The apparent increase in the prevalence of autism over the last 20 years corresponds with increasing medical advice to avoid the sun, advice that has probably lowered vitamin D levels and would theoretically greatly lower activated vitamin D (calcitriol) levels in developing brains. Animal data has repeatedly shown that severe vitamin D deficiency during gestation dysregulates dozens of proteins involved in brain development and leads to rat pups with increased brain size and enlarged ventricles, abnormalities similar to those found in autistic children. Children with the Williams Syndrome, who can have greatly elevated calcitriol levels in early infancy, usually have phenotypes that are the opposite of autism. Children with vitamin D deficient rickets have several autistic markers that apparently disappear with high-dose vitamin D treatment. Estrogen and testosterone have very different effects on calcitriol's metabolism, differences that may explain the striking male/female sex ratios in autism. Calcitriol down-regulates production of inflammatory cytokines in the brain, cytokines that have been associated with autism. Consumption of vitamin D containing fish during pregnancy reduces autistic symptoms in offspring. Autism is more common in areas of impaired UVB penetration such as poleward latitudes, urban areas, areas with high air pollution, and areas of high precipitation. Autism is more common in dark-skinned persons and severe maternal vitamin D deficiency is exceptionally common the dark-skinned. Conclusion: simple Gaussian distributions of the enzyme that activates neural calcitriol combined with widespread gestational and/or early childhood vitamin D deficiency may explain both the genetics and epidemiology of autism. If so, much of the disease is iatrogenic, brought on by medical advice to avoid the sun. Several types of studies could easily test the theory.http://www.medical-hypotheses.com/article/S0306-9877(07)00537-3/abstract
I'm posting the above for purposes of discussion. I have no, repeat no, opinion on whether there is a link between vitamin D levels and autism.
Marylin,
John Cannell thinks Vit D is the answer to just about any disorder including cancer.
http://www.tanformation.com/forums/showthread.php?t=29775
"As I've said before, if I had cancer, I'd take 5,000 IU of vitamin D every day in the colder months. In the warmer months, I'd stop the vitamin D and get a safe amount of noontime sunshine. I'd keep my 25-hydroxy-vitamin D levels between 50 and 70 ng/ml, year around. However, I do that now and I've not been diagnosed with cancer.
Hypotheses aside, has he presented anything like a plausible biological mechanism? I may have missed it if he has.
notmercury,
I assume he discusses biological plausibility in his article. I haven't read it.
I'm familiar with his website and his newsletter.
I believe Orac plans to discuss the evidence on vitamin D and cancer in a future post. I look forward to reading his thoughts.
This study is further proof that epidemiology is one of the hardest of the sciences to perform correctly. That might not be so bad if it weren't also one of the most important of the sciences.
For vit. D and cancer :
hydroxy-vitamin D is a known differentiation agent in-vitro for HL-60 cells (we use it as a positive control along with retinoic acid). I know retinoic acid (vit. A) is used in cancer treatment for acute myeloid leukemia, I don't know if hydroxyvit. D is used at all in cancer treatment.
Vit. D is also a pro-hormone (that is, used in the biosynthesis of a hormone) that modulates the immune system with debatable positive or negative effects on cancer rates and/or progression. I would abstain to predict which, keeping in mind the fiasco of antioxidants, and the demonstrated fact that macrophages help breast cancer cells to reach the bloodstream and metastatize. So using something that stimulates phagocytosis to treat an existing cancer may be quite a bad idea.
However, when anyone starts talking about a product that prevents or cure all cancers, I hear quacking sounds (I have woo-induced tintinus;-).
I would have picked "Rain Fall-Guy" as the headline myself...
...also I don't know a thing about statistics or medicine. It is my [entirely uneducated] opinion, however, that this study is a pile of horse manure. Its authors must have been watching too much House.
Kemist:
Interestingly my lab is looking at adding retinoic acid (vit A) to our HIV vaccine strategies because it induces T-cells to home to the lymphoid tissues of the gut. Given some of the things I have read here about gut problems in autistic children, who wants to bet vitamin A will be the next big thing?Given some of the things I have read here about gut problems in autistic children, who wants to bet vitamin A will be the next big thing?
Already been/being done by the DAN! quacks, often with disastrous results.
Interestingly my lab is looking at adding retinoic acid (vit A) to our HIV vaccine strategies because it induces T-cells to home to the lymphoid tissues of the gut.
cis or trans RA?
No no, they got this all wrong, it's autism that cause rain! Autism makes god cry!
- Link Between Precipitation and Autis... LCD
16 y
4,809
Huge agreement on urbanicity:
New Jersey: ~90% urban
Total US: 79% Urban
Alabama: 55% urban
The latitude seems like a less important variable, especially since New Jersey is the second-most-northern state. I'm guessing the CDC did not make the latitude->autism link in its conclusions.
Posted by: Grep Agni | November 5, 2008 9:58 AM