http://www.snopes.com/medical/toxins/glyphosate.asp
Correlation != Causation and not every scientist is an expert on Autism/Genetics/Biology.
"Even disregarding the sloppy mathematics, the claim's very basis (that glyphosate is the cause of a perceived increase in autism) is unsupported. No mention was made of how glyphosate was isolated and shown to be a cause (or even a factor) in some or any cases of autism in the article. No autism spikes near agricultural facilities were described, nor was any definitive causative link at all cited by the article (and presumably, Seneff) to back up the purported link between glyphosate and autism rates anywhere other than the imaginations of those making the claim. The single link of merit made within the article (to a USDA report) made absolutely no mention of autism at all but was misleadingly arranged to suggest a connection.
What the claim seemed to hinge on largely was a correlation/causation fallacy: Because [unclear activity involving glyphosate] occurred, a corresponding rise in autism diagnoses must be due to that unspecified issue with glyphosate. Claims of a similar nature have been dispelled with graphs like the following that show how difficult (or simple) it is to "prove" any one cause correlates with any one effect:"
So we've seen that shift. The diagnostic criteria changed a lot, not just a little, over time.
By coincidence, Wakefield launched his fraudulent crap about vaccines a few years after the criteria were broadened, and that became the popular explanation rather than the fact that the criteria changed. Belief in his BS is perhaps fading but it's still around.
The "epidemic" was predicted and an intentional outcome of the DSM criteria change, though.
If you hang out with a bunch of families with autistic kids, it's very obviously inherited in a large fraction of cases, because the kids are so much like their parents.
Another large fraction is likely genetic in the sense of "de novo" mutation, rather than inherited genes. There's likely also a group of environmental cases, mostly prenatal environmental factors.
Because social function depends on many coordinated aspects of human cognition, any condition that has a fairly global effect on the brain can create traits meeting the autism diagnostic criteria. The criteria are very broad, with many different ways to meet them.
It's important to realize that autism is a broad category, not a single condition, and no proposed single gene or environmental factor ever seems to relate to more than a few percent of cases. https://intellectualizing.net/2013/12/17/book-rethinking-aut...
Some of those causes could well be new to the modern world, but the changing diagnostic criteria do explain most of the expansion in diagnoses already, so there isn't a lot of evidence that we need to be looking for something novel to explain the increased diagnoses.
My son is the third or fourth generation to be likely-diagnosable, for example.
Currently-middle-aged parents without intellectual disability had almost zero chance of being diagnosed as children, because when we were kids autism was defined such that you usually had to be nonverbal or intellectually disabled to qualify.
A very commonly-reported experience is for parents to be diagnosed after their children are diagnosed.
There are some evidence that hints to genetic factors. For example, we know that boys are at much higher risk than girls, but we don't know why. Similarly, we know that older parents are more likely to have autistic children—but again, we don't know why.
Also the boy/girl factor could be explained by different behaviors, so different exposures.
Not saying I know anything about this, or that this is the case, just that the increased family risk and boy/girl risk doesn't mean it is genetics.
That's correct, but looking at concordance rates between monozygotic (identical) and dizygotic (fraternal) twins demonstrates that there is at least a partial genetic connection.
Identical twins share the diagnosis in 77% of cases, while fraternal twins only share the diagnosis in 31% of cases.[1] Given that identical twins share more genetic material, the conclusion is that autism has a genetic component to its incidence.
That said, most research on the subject, including the paper I'm citing, establishes that there is most likely a dual nature-nurture component. In particular, this study was conducted on twins within the same household, so the genetic component would have been augmented by shared environmental factors.
The implication seems to be that the parents also exhibit traits of the autism spectrum, so it's hardly surprising that their kids would do the same.
Despite the quantity of autism research, most of it is quite bad and not that helpful on questions like this.
"Environmental" can include "parenting", but in this case the distinction is between "got it somehow from autistic-leaning parents" vs got from something else.
Also, the claim that autism might be somehow learned from parents is extraordinary and not widely claimed or supported by existing evidence. It was a discredited theory of the past though, that "cold" parenting created austism.
http://www.npr.org/sections/health-shots/2015/09/02/43674237...
(Audio controls in the left margin.)
He addresses that a fair bit, mentioning that autism is one of the most heritable conditions, and talking a lot about the history of the diagnosis and how it was artificially narrow for a long time.
Personally, my bet is that we'll come to see a lot of autism diagnosis as part of a broader pattern of medicalization of deviance from the norm. And that even the forms we eventually decide are harmful have for nerds the same relationship that sickle-cell anemia does to malaria resistance: a trait that is useful in small doses but can be harmful in large ones.
If there is an actual increase, I'd bet on it being due to stronger assortative mating that has come as mate choice has less to do with geographic factors and more with education and workplace.
Well, considering the fact that "heritability" is a measure of how much of a given phenotype's expression is due to genetic variation, probably not soon. "Heritable" is not a word used to refer to environmental factors such as parental care and upbringing. In studies on heritability of specific traits, these environmental factors are used as classifications for broader observations of genetic variations (for example, in twin studies, was twin pair A raised in the same household like pair B?).
Going back to autism specifically, the Simons Foundation Autism Research Initiative identified a single genetic mutation that accounted for 25% of diagnoses in their Simplex Collection[1], while the other 75% were impacted by 200-400 different genes. This data is available online as of 2016[2], though some analyses may be paywalled.
[1]: https://sfari.org/resources/autism-cohorts/simons-simplex-co...
[2]: https://www.simonsfoundation.org/features/foundation-news/si...
http://www.forbes.com/sites/tarahaelle/2015/01/05/majority-o...
Its also discussed here on Fresh Air by the author of a book on Autism called Neurotribes.
" But because no one really explained to parents exactly what had happened - that the diagnosis had been completely rewritten - that, you know, autism by the end of the 1980s and the early 1990s was not your grandfather's autism, you could say. It was much more broadly defined because no one ever explained to the lay public what had happened with the diagnosis. When the numbers started going up, parents very understandably became very alarmed. And the media was sort of blindsided by the sudden spike in diagnoses."
http://www.npr.org/2016/09/09/493148713/neurotribes-examines...
It might be because some ASD traits help people become more successful in the information economy. Asperger's people often thrive in well-paid occupations such as programming and data analysis where spontaneous social interaction is widely acknowledged to hurt productivity.
Or it might just be a side effect of a society that places a lot of emphasis on intelligence, making it more likely for a person with high IQ to seek a mate with similarly high IQ. The more smart people "inbreed" among themselves, the more ASD cases we will naturally see.
In either case, since evolution is whack-a-mole, this will lead to not only mild ASD but also more cases of severe autism if they are caused by the same set of genes.
I do believe that children with Asperger Syndrome often see the symptoms grow less severe as they age. Perhaps with lots of hard work and a good support structure, some of them people grow to enjoy above average success. It seems entirely unreasonable (and to my mind somewhat cruel) to credit this success to Asperger Syndrome itself.
http://www.npr.org/sections/health-shots/2015/09/02/43674237...
An allergy or intolerance is much worse when it make your nonverbal child irritable and violent, then when it makes your verbal child say "mom, my tummy hurts bad" after you serve pizza.
I'm put in mind of the recent paper posted on HN regarding magnetic nanoparticles being found in human brains. Unrelated to autism (probably) is the increasing study of prions and in general, maladaptive protein synthesis. What isn't known about these issues could fill volumes.
And of course there's this whole field called epigenetics that studies how the same genes can be expressed differently based on environmental factors.
https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-...
You're confusing increase in diagnosis versus increase in autism. This confusion is the whole basis of the "autism epidemic" claim.
"Shifting diagnoses and heightened awareness explain only part of the apparent rise in autism. Scientists are struggling to explain the rest."
Takeaway: it's a mix of both genetics and environment.
https://www.ted.com/talks/wendy_chung_autism_what_we_know_an...
That chart shows the rate of increase in autism diagnosis, which is not the same.
http://www.nature.com/news/2011/111102/full/479022a/box/1.ht...
Now that's a very scary chart if you start to project that curve into the future.
Here's another one. Not saying this is the cause, but it is a cause for concern. We have many similar patterns of environmental factors increasing with autism prevalence, which makes the likelihood of it being environmental stronger than something else.
http://images.medicaldaily.com/sites/medicaldaily.com/files/...
For example it took a long time to figure out that lead in gasoline could lead to cognitive decline. BPA and phtalates is another recent discovery, which cause hormone distruption.
What else do we have today that is yet to be figured out, and what is the likelihood that we have something similar brewing that we do not yet know about.