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I don't quite buy that autism will be shown to be genetic. I think it's an environmental factor. The rate of increase in autism is pretty much exponential: htt

I don't quite buy that autism will be shown to be genetic. I think it's an environmental factor. The rate of increase in autism is pretty much exponential: http://www.nature.com/news/2011/111102/full/479022a/box/1.html 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/styles/full_breakpoints_theme_medicaldaily_desktop_1x/public/2015/01/05/autism-prevalenceuse-glyphosate.JPG 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.

jarmitage 10y ago
It is not prevalence that is growing exponentially, it is diagnosis.
hoopism 10y ago
I am not dismissing the idea that environmental causes may be at play... but be VERY VERY cautious when throwing around charts like that. http://www.snopes.com/medical/toxins/glyphosate.asp 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:"
kijin 10y ago
It doesn't need to be one or the other. Genetics can predispose somebody to be more vulnerable to certain environmental factors. They will not show any symptoms unless those environmental factors are present, but there's still genetics involved. And of course there's this whole field called epigenetics that studies how the same genes can be expressed differently based on environmental factors.
M_Grey 10y ago
There are a lot of potential candidates... too many to be honest, and a lot of them are related to basic economic activities. History shows that environmental issues driven by economics aren't solved until an alternative comes along and is adopted; the problems of dead horses and horse dung in NYC streets were solved by... the automobile. 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.
3pt14159 10y ago
My cousin had debilitating autism that was greatly diminished by removing wheat germ from his diet, so I partially buy the environmental take, but on the other hand it is a disease that is correlated with parental IQ, where a higher IQ leads to more likely incidence of autism. I don't think it's a coincidence that the rise of co-sexed secondary education and finer grained sorting with institutions like Harvard and MIT getting an even more concentrated amount of intelligent people.
- kijin 10y ago
  Since this thread is about evolution, we might even say that the evolutionary pressures we currently face in the developed world actually favor mild variants of ASD. 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.
  - stri8ted 10y ago
    Being economically successful in the western world, does not necessarily translate to more (surviving) offspring.
    - lithos 10y ago
      But it does ensure your child/ren have access to medical professionals, which causes what the medical community as a whole to see an increase in cases.
  - cmiles74 10y ago
    I have not seen any evidence that Asperger Syndrome or mild autism leads to well-paid occupations. For sure, there is some anecdotal evidence (which I find unconvincing), but I haven't come across anything more solid, like a research paper or study. If you've seen something along those lines, please post a link. 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. https://en.wikipedia.org/wiki/Asperger_syndrome https://en.wikipedia.org/wiki/Asperger_syndrome
hannob 10y ago
> I don't quite buy that autism will be shown to be genetic. I think it's an environmental factor. The rate of increase in autism is pretty much exponential: You're confusing increase in diagnosis versus increase in autism. This confusion is the whole basis of the "autism epidemic" claim.
- adsfqwop 10y ago
  Am I? The Nature article explicitly states that the shift in diagnosis criteria does not fully explain the increase in numbers. "Shifting diagnoses and heightened awareness explain only part of the apparent rise in autism. Scientists are struggling to explain the rest." http://www.nature.com/news/2011/111102/full/479022a.html http://www.nature.com/news/2011/111102/full/479022a.html
QuotedForTruth 10y ago
Another possible explanation for such a rise that I have seen repeatedly given is that the methods and basis for diagnosis changed in the early 90s. http://www.forbes.com/sites/tarahaelle/2015/01/05/majority-of-autism-increase-due-to-diagnostic-changes-finds-new-study/#3461baaa737c 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-the-history-and-myths-of-the-autism-spectrum http://www.npr.org/2016/09/09/493148713/neurotribes-examines...
i14ng 10y ago
When the autism diagnostic criteria were broadened in the DSM, the people making that change predicted that we would see this rise in diagnostic rates. That was the intent, to help a broader range of people. It's played out slowly as clinicians and schools were retrained. There's also been an increasing incentive to diagnose as autism in addition to intellectual disability when possible, because insurance companies and schools will do a lot more if it's labeled autism. 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-autism-variation-and-complexity/ 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.
- euyyn 10y ago
  Can you give more details on the "some of them are obviously inherited, because the kids are so much like the parents" part? Kids everywhere are so much like their parents, so the reasoning, as written, is nonsense.
  - s_kilk 10y ago
xutopia 10y ago
What if the markers are recessive and the social fabric today means more people with the recessive genes procreate?
- douche 10y ago
  I'm not sure if more people with the recessive genes procreate now vs in previous eras, in total; I suspect that more couples that carry autism-related genes are procreating with each other, due to increased prevalence of educational and intelligence-based assortive mating.
jawarner 10y ago
I disagree, I find it intuitive that autism is genetic. View autism as a genetically induced alternate brain development. Usually it doesn't pan out, but sometimes it leads to innovation that wouldn't otherwise be possible. This leads to a survival advantage for a given subpopulation, which is sufficient for natural selection.
Spellman 10y ago
Simple TED talk explaining what we know and what we know doesn't cause Autism. From 2014. Takeaway: it's a mix of both genetics and environment. https://www.ted.com/talks/wendy_chung_autism_what_we_know_and_what_we_don_t_know_yet?language=en https://www.ted.com/talks/wendy_chung_autism_what_we_know_an...
wpietri 10y ago
I'd strongly recommend you listen to Steve Silberman, Neurotribes author, on Fresh Air: http://www.npr.org/sections/health-shots/2015/09/02/436742377/neurotribes-examines-the-history-and-myths-of-the-autism-spectrum 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.
- nerdponx 10y ago
  When are we going to finally ditch the idea that heritable==genetic?
  - dsacco 10y ago
    >>When are we going to finally ditch the idea that heritable==genetic? 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-collection https://sfari.org/resources/autism-cohorts/simons-simplex-co... [2]: https://www.simonsfoundation.org/features/foundation-news/simons-simplex-collection-autism-data-now-available-online/ https://www.simonsfoundation.org/features/foundation-news/si...
joeln502 10y ago
Small correction. We knew full well that lead was toxic, with adverse cognitive effects, before introducing it to gasoline. https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-a-short-sad-history https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-...
PlugTunin 10y ago
FACT: Asperger's runs in families. Nuff said.
fasteo 10y ago
>>>> The rate of increase in autism is pretty much exponential That chart shows the rate of increase in autism diagnosis, which is not the same.

jarmitage 10y ago

It is not prevalence that is growing exponentially, it is diagnosis.

hoopism 10y ago

I am not dismissing the idea that environmental causes may be at play... but be VERY VERY cautious when throwing around charts like that. http://www.snopes.com/medical/toxins/glyphosate.asp 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:"

kijin 10y ago

It doesn't need to be one or the other. Genetics can predispose somebody to be more vulnerable to certain environmental factors. They will not show any symptoms unless those environmental factors are present, but there's still genetics involved. And of course there's this whole field called epigenetics that studies how the same genes can be expressed differently based on environmental factors.

M_Grey 10y ago

There are a lot of potential candidates... too many to be honest, and a lot of them are related to basic economic activities. History shows that environmental issues driven by economics aren't solved until an alternative comes along and is adopted; the problems of dead horses and horse dung in NYC streets were solved by... the automobile. 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.

3pt14159 10y ago

My cousin had debilitating autism that was greatly diminished by removing wheat germ from his diet, so I partially buy the environmental take, but on the other hand it is a disease that is correlated with parental IQ, where a higher IQ leads to more likely incidence of autism. I don't think it's a coincidence that the rise of co-sexed secondary education and finer grained sorting with institutions like Harvard and MIT getting an even more concentrated amount of intelligent people.

kijin 10y ago
Since this thread is about evolution, we might even say that the evolutionary pressures we currently face in the developed world actually favor mild variants of ASD. 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.
- stri8ted 10y ago
  Being economically successful in the western world, does not necessarily translate to more (surviving) offspring.
  - lithos 10y ago
    But it does ensure your child/ren have access to medical professionals, which causes what the medical community as a whole to see an increase in cases.
- cmiles74 10y ago
  I have not seen any evidence that Asperger Syndrome or mild autism leads to well-paid occupations. For sure, there is some anecdotal evidence (which I find unconvincing), but I haven't come across anything more solid, like a research paper or study. If you've seen something along those lines, please post a link. 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. https://en.wikipedia.org/wiki/Asperger_syndrome https://en.wikipedia.org/wiki/Asperger_syndrome

hannob 10y ago

> I don't quite buy that autism will be shown to be genetic. I think it's an environmental factor. The rate of increase in autism is pretty much exponential: You're confusing increase in diagnosis versus increase in autism. This confusion is the whole basis of the "autism epidemic" claim.

adsfqwop 10y ago
Am I? The Nature article explicitly states that the shift in diagnosis criteria does not fully explain the increase in numbers. "Shifting diagnoses and heightened awareness explain only part of the apparent rise in autism. Scientists are struggling to explain the rest." http://www.nature.com/news/2011/111102/full/479022a.html http://www.nature.com/news/2011/111102/full/479022a.html

QuotedForTruth 10y ago

Another possible explanation for such a rise that I have seen repeatedly given is that the methods and basis for diagnosis changed in the early 90s. http://www.forbes.com/sites/tarahaelle/2015/01/05/majority-of-autism-increase-due-to-diagnostic-changes-finds-new-study/#3461baaa737c 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-the-history-and-myths-of-the-autism-spectrum http://www.npr.org/2016/09/09/493148713/neurotribes-examines...

i14ng 10y ago

When the autism diagnostic criteria were broadened in the DSM, the people making that change predicted that we would see this rise in diagnostic rates. That was the intent, to help a broader range of people. It's played out slowly as clinicians and schools were retrained. There's also been an increasing incentive to diagnose as autism in addition to intellectual disability when possible, because insurance companies and schools will do a lot more if it's labeled autism. 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-autism-variation-and-complexity/ 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.

euyyn 10y ago
Can you give more details on the "some of them are obviously inherited, because the kids are so much like the parents" part? Kids everywhere are so much like their parents, so the reasoning, as written, is nonsense.
- s_kilk 10y ago

xutopia 10y ago

What if the markers are recessive and the social fabric today means more people with the recessive genes procreate?

douche 10y ago
I'm not sure if more people with the recessive genes procreate now vs in previous eras, in total; I suspect that more couples that carry autism-related genes are procreating with each other, due to increased prevalence of educational and intelligence-based assortive mating.

jawarner 10y ago

I disagree, I find it intuitive that autism is genetic. View autism as a genetically induced alternate brain development. Usually it doesn't pan out, but sometimes it leads to innovation that wouldn't otherwise be possible. This leads to a survival advantage for a given subpopulation, which is sufficient for natural selection.

Spellman 10y ago

Simple TED talk explaining what we know and what we know doesn't cause Autism. From 2014. Takeaway: it's a mix of both genetics and environment. https://www.ted.com/talks/wendy_chung_autism_what_we_know_and_what_we_don_t_know_yet?language=en https://www.ted.com/talks/wendy_chung_autism_what_we_know_an...

wpietri 10y ago

I'd strongly recommend you listen to Steve Silberman, Neurotribes author, on Fresh Air: http://www.npr.org/sections/health-shots/2015/09/02/436742377/neurotribes-examines-the-history-and-myths-of-the-autism-spectrum 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.

nerdponx 10y ago
When are we going to finally ditch the idea that heritable==genetic?
- dsacco 10y ago
  >>When are we going to finally ditch the idea that heritable==genetic? 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-collection https://sfari.org/resources/autism-cohorts/simons-simplex-co... [2]: https://www.simonsfoundation.org/features/foundation-news/simons-simplex-collection-autism-data-now-available-online/ https://www.simonsfoundation.org/features/foundation-news/si...

joeln502 10y ago

Small correction. We knew full well that lead was toxic, with adverse cognitive effects, before introducing it to gasoline. https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-a-short-sad-history https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-...

PlugTunin 10y ago

FACT: Asperger's runs in families. Nuff said.

fasteo 10y ago

>>>> The rate of increase in autism is pretty much exponential That chart shows the rate of increase in autism diagnosis, which is not the same.