A big part of the problem is that, even as we’ve gotten better at diagnosing it, autism isn’t a specific condition. It’s a collection of different conditions whose symptoms all fall into one loose category. So any attempt to find a single cause for it is going to get you a whole mess of possibilities.
Genetics, vitamin D deficiency (in both the mother before birth and in the child later), environmental toxins, metal sensitivities and poisonings, dietary concerns. They’ve all been implicated to some degree or another, but until we get better at classing specific cases by cause rather than result, the mess is going to be all over the place. And yes, that’s a very circular problem; that’s part of why it’s such a tough nut to crack.
(Imagine what it was like trying to cure illnesses before the difference between bacteria and viruses was nailed down, and remove knowledge of vitamin deficiencies and dietary effects as well. All you know is people get sick, but it’s impossible to point to any specific cause or treatment. Antibiotics only help one out of four of those base causes, so without understanding how to separate them, they barely look effective on the whole)

Frankly, I’m skeptical.
My husband’s father, born around the turn of the last century and now deceased, was as clear a case of Asperger’s Syndrome as you can imagine. He grew up in the country, far from any “industrial toxins.” His son is mildly affected; of our four children, three have Asperger’s.
Diagnosis has changed; I can’t see that the condition has changed, at least not in our family. Neither my father-in-law nor my husband were ever diagnosed with anything, and only one of my children has a formal diagnosis. But for that child, all these people function and functioned reasonably well, though the condition is not without its effects.
We have a tendency to blame all the ills of humanity on “industrialism” and/or “pollution.” I’m certainly not in favor of spewing poisons into the environment, but come on, life was not without its difficulties in past centuries, and many of them were the same difficulties.

The issue I have with the environmental toxins hypothesis is that since the 1970′s the US has gotten much cleaner environmentally. But the increase in autism diagnosis didn’t start until the 1980′s. In addition prenatal care is much more sophisticated now then in the 60′s and 70′s.
If there was a causative relationship you would expect the bump in diagnosis to correlate, not be anti-correlated.
The only way I would think toxins would be a cause is is if they damaged the reproductive cells of the previous generation. So it skipped a generation between cause and effect.

There’s much to what Oda says. I have a close relative diagnosed with Asperger’s, and I can now see the undiagnosed Asperger cases in my family among the older generations, some of whom grew up in rural Ireland, were never vaccinated, and were not exposed to chemicals in the womb. Karl G’s point about autism being a collection of different conditions is also correct. There really is no autism, but there are autisms.

The fact that he brings up toxins leaking from plastics in the microwave, says he comes from a certain school of thought. I know these types, they have a strange fear of chemicals, and a strange trust in anything organic or natural. There is danger in everything we do, but there are also benefits… We live in a world of false dichotomy.
When I was a kid, we came in contact with so many more toxic things than we do today. Kids are practically brought up in sterile environments now. Yet we have this strange tendency to keep thinking the world is becoming more polluted, more toxic.
Heck when I was a kid, half the rivers in this country were too polluted to fish in, now it’s near impossible to find a single river with pollution warnings. There used to be a smog cloud over LA every day, I can’t remember the last time I saw one, every garage in the suburbs used to be a toxic dump!

“One uncertainty is to what extent the reported increases in autism simply reflect a more common diagnosis of what might previously have been called mental retardation.”
When I was growing up in the 70s, the word autism was rarely if ever used, but I knew lots of kids that were said to be “mentally retarded.” I’m sure that someone could do some research to clarify this issue…

It is easy to see that Aspergers could be under diagnosed as there are plenty of functioning people with Aspergers who have merely been classified at introverted or socially awkward, but they can find a place in life where they can be amply successful (Like being a professor), but severe Autism is also on the rise. Given how profoundly non-functional these individuals are, there would have to be a corresponding drop in another diagnosis to account for the “misdiagnosis.” But we can’t find it …
Clearly there is a genetic component and clearly there is an environmental component. We simply have to look harder.

Mercury

Actually Rod the increase in autism seems most strongly related to the fact of older-and-older people having children. These people tend to have greater wealth, thus more diagnoses but also less willingness to consider an intrinsic or genetic component to this condition.
Were autism a result of extrinsic environmental toxins we would expect to see clusters of autism where we see clusters of environmentally-linked cancers and asthma, but we don’t.

Rod, fellow giftie and long-time reader (and first-time commenter) here…
It is perhaps disingenuous to use the examples of thalidomide and misoprostol as harbingers of autism. The wide spectrum of birth defects caused by thalidomide is widely documented and misoprostol is used to induce labor or to help a woman along with expelling a miscarried pregnancy (or yes, an abortion, but that is not the discussion here). Autism is the least of what these drugs can do.
That being said, there is probably something to this theory. As a fairly skeptical person, I’m not prepared to jump on the vaccinations = autism bandwagon, but I think the science may yet prove that there is a plausible link between birth defects and manufactured chemicals, whether encountered in the environment or taken in via food or medicine. But I think it may have more to do with exposure to the mother during pregnancy than the child after it is born (which is why the vaccine theory does not hold for me). We’re a resilient species, once we’re out in the world.

“the increase in autism seems most strongly related to the fact of older-and-older people having children. These people tend to have greater wealth, thus more diagnoses but also less willingness to consider an intrinsic or genetic component to this condition.”
Exactly. Autism is very much a SWPL condition, which explains the rise in diagnosis, the media attention it now receives, and the amount of speculation that surrounds it. The correlation between affluence and autism is actually a more interesting relationship to consider. It’s not consumption, necessarily, but the condition of affluence and privilege.

“the increase in autism seems most strongly related to the fact of older-and-older people having children. These people tend to have greater wealth, thus more diagnoses but also less willingness to consider an intrinsic or genetic component to this condition.”
One theory I’ve heard is that some people who marry later than average might be slightly autistic themselves and have delays in maturity and forming the sorts of relationships that lead to marriage. So, the cohort of those who are marrying later might already have a higher level of autistic-spectrum individuals than the general population. Since autism does seem to have a genetic component, these individuals have a greater chance of producing offspring with the condition.

I agree with Oda and Appalachian Prof. I was born in 1982 and probably have Asperger’s, but wasn’t diagnosed since it didn’t even become a diagnosis until I was in 7th grade. There were a few other kids like me at school, and we were all basically thought of as “weirdos.” On the other hand, my aunt, who’s a children’s speech pathologist, says she sees fewer clients with a diagnosis of severe retardation, and many more with a diagnosis of autism. I’m not saying environmental factors have no role in the increase (I have no idea either way), but the widening criteria for autism must be a big contributor, one that’s often glossed over.

Yeah – mercury. It is certain that we have removed many toxins from the environment but lots of others will remain for centuries. PVC’s are still in the water and mercury is everywhere (if you live near a coal burning power plant – you are ingesting mercury every time you breathe). So we shouldn’t be complacent about toxins or dismiss any notions that toxins can cause disease.
There has also been some research on hot spots – areas where the rate of illness, miscarriage and children born with assorted disabilities is much higher than normal. One such cluster was an autism cluster – located close to a plant which made sunglasses – seems the process of making sunglasses includes some nasty chemicals. One of the most notorious of these hot spots was in southern Jersey- for decades residents in the area kept insisting something was wrong and their complaints were dismissed – until a coalition forced the state to test the aquifer and it was revealed that the drinking water was a stew of carcinogenic and other highly toxic chemicals. The state had to shut down the withdrawal of water from the aquifer it was so poisonous creating an ongoing water availability problem in the area.The same sorts of statements being made now in rejecting the idea that industrial toxins may cause some forms of autism were made to those people – that the higher rates of assorted problems were a function of older mothers, better diagnosis etc etc – but in the end – it was none of that – those people were truly being poisoned by their drinking water.
I suspect at some point it may be demonstrated that there is a causal link between exposure to some industrial pollutants and some forms of autism – consider that as recently as the 60′s it was absolutely believed that autism was caused by maternal rejection. Think of the pain and guilt experienced by all those mothers who were told they had caused their child’s autism – yet no one today would seriously think of maternal rejection as a cause of autism. So it seems to me that we might keep on open mind on these claims.
The breast cancer thing is another really disturbing trend – especially when we see increasing rates of breast cancer in young women.

Peter made reference to autism being a SWPL condition, and a possible correlation between affluence and autism.
That made me think of something, that may not make sense, but I’ll throw it out anyway. Maybe autism (and other psychological based disorders) have a higher chance when people marry other people who are too similar.
I don’t mean similar physically, or similar values or personality. I mean similar very specific ways of thinking. These traits get magnified in the child, and this leads to a higher chance of problems.
If you spend 10 to 15 years waiting for that perfect person, maybe you’ll find someone too perfect? This would explain higher autism rates in higher education couples, and not as much autism in couples with only high school degrees. (I’m assuming this is true.)
But I’m also open to environmental factors contributing to autism, breast cancer, etc.

“”There are diseases that are increasing in the population that we have no known cause for,” ”
or it could be due to better diagnostic methods. for example I was diagnosed with prostate cancer 4 years ago. This after 3 biopsies within an 18 month period of time. The first biopsy was reviewed by 5 count’em 5 pathologists. Two said we don’t see anything, 1 was ambivalent, 2 said yes. so six months later back for another biopsy, same thing, 3rd biopsy finds out of 8 samples 1 incidence of cancer. Prostate cancer can lie dormant for years no one knows when it will come alive.
every seen the Ernie Els advert about autism? the ad says 1 child out of 150 is diagnosed with autism. could that be because the diagnosis was broadened? could it be because federal disability laws give advantages to such children? I’ve read reports where parents are pushing for their children to be diagnosed with autism, ADD, ADHD almost anything so they get a leg up on the ‘normal’ kids.
If all you have in your hand is a hammer then all your problems will look like nails

I recently compiled a study of Somali immigrant families where there is much higher proportion of autistic first generation children than the general native population. This might substantiate the “toxin” thing and also substantiate the Weston A. Price people with their traditional diets.

On just the first page of Kristof’s comments, proposals are made that autism may be caused by:
1. TV
2. Marijuana
3. Bisphenol A
4. Cell phones
5. Vaccination shots
6. Too FEW chemicals in the environment
7. Artificial contraception
8. Baby formula
9. Microwave food in plastic containers
10. Aspartame
On other Internet sites, numerous other proposals have been made, such as 11. The increased average age of first pregnancy. I once saw mention made somewhere of a racist website that had devised an argument that the rise had somehow been caused by 12. An increase in Indian immigration.
If the increase in autism is real rather than merely caused by changes in diagnosis, something must be behind it. I think this shows, however, that no one really has any idea what the cause is and each person just points the finger at something he is already predisposed to dislike.

Just to throw out another “explanation”, I was at a small meeting of public health physicians recently and the increase in sonograms was proposed as a contributing factor.

I absolutely agree with the idea that diagnosis increases are more a result of the modern environment and our tendency to label all differences. Years ago, a “strange and slow child” could easily forego school, work the family farm or a simple labour job. Now, with most work requiring at minimum a high school diploma, these people are more likely to be noticed and labelled.
Work examining this through examination of old medical files suggests the increase is simply one of increased diagnosis.

While not being one to jump on Kristof’s bandwagon just yet, I do think we should take it seriously. We know, for example, that certain foods and chemicals in prepared foods have quite an adverse impact on the bahvior of lots of kids (and adults) with certain types and/or levels of autism. I think of a couple of my students with Asperger’s. It certainly seems possible that exposure to certain chemicals or pharmaceuticals in sufficient amounts could cause problems in the womb.
Someone above said “Autism is very much a SWPL condition.” That’s simply not true. Aside from anecdotal evidence (one of my Asperger’s students is Ecuadoran, another is Korean), demographic studies show nothing of the sort.
I suspect many more people today are diagnosed with “autism spectrum disorders’ because we recognize autism today as encompassing a wide spectrum, and because we have better diagnostic tools. In years past many Asperger’s people would simply have been put down as nerds, clumsy, little professors, socially inept, etc.

One thing that I think might help sort out this controversey is getting an ability to map epidemiological and environmental and socio-economic data so that you can see the “hot spots” of autism like Brick Township in NJ or Silicon Valley. This mapping won’t prove causality but it can show the correlations between the environment or population characteristics and disease. You know we have had the “golden age of chemistry” where we have found 10′s of thousands of new chemicals but we have safety standards for relatively few of these new chemicals.
I am blogging about my experience as a adult diagnosed late in life (age 50) with an ASD and will be blogging in the future about the learning disorder and the environment factors. Right now, I am rather wrapped up in trying to get my basic senses working correctly so I am just noting environmental concerns in passing. From a lay persons perspective, it is very hard to figure out what is a real concern and what is voodoo. If you look at a consensus of authoritative sources ie the Centers of Excellence on Autism, you get very watered-down statements that there is likely to be some environmental-genetic connection but no one in these institutes wants to go out on a limb and say categorically what the connection is. You are in the position of trying to sort out scientific controversies to which you don’t have the background to really weigh in. At the end of the day, you make a few hypotheses as to what might possibly affect your particular situation. At this point, I am still gathering evidence. Also, historically, I am a “lazy green”. I like being green but I don’t want to expend much energy to be green. I do prefer organic foods–I belong to a community supported agriculture farm and try to buy meat at farmer’s markets when I can see it at a good price. But as far as getting into all the green cleaning fluids and VOC paints, I am still trying to come to a conclusion.