Wednesday, September 23, 2015

Does new genetic study refute the tenets of neurodiversity?

The main belief of the neurodiversity movement is that autism is a naturally occurring genetic variation.  The differences in the brains of autistic persons versus those of  "neurotypicals" are no more significant than differences between blondes and brunettes.  A common belief is that numerous genes in small amounts accrue certain evolutionary benefits but in large amounts cause autism.  According to Simon Baron-Cohen and Temple Grandin the reason autism has stayed in the population despite the fact that autistic people usually don't have children is that it  has traits that are adaptive and have evolutionary value.  For example attention to detail as measured by the embedded figures test, high scores on the block design test and pattern recognition.  Grandin has gone so far as to say that we'd all be cavemen if it weren't for autism genes.

New research from the Cold Spring Harbor Laboratory in New York would seem to refute that contention.  The scientists found that a number of cases of autism to be caused by rare genetic mutations in vulnerable genes.  These mutations were spontaneous, and due to the fact that autistics rarely reproduce these mutations don't stay in the population.  In some cases, they were transmitted by the mother who was less vulnerable to the mutation and did not become autistic.   Here is the study in its entirety in case anyone is interested in reading it. I read it, albeit with limited understanding, not being a scientist.

The scientists used a databank from the Simons Foundation that included multiple families with one autistic child.  Of course, one limitation is that they did not study multiplex families in which more than one child has autism.  This is not an uncommon occurrence as siblings of autistic children are far more likely to have autism than a child in the general population.  With fraternal twins it is more likely than in siblings.  In identical twins there is an even higher concordance rate, though not 100%.  Gadfly wonders if different results would be found for families with more than one autistic offspring.  Is it possible they have different genetic mutations or environmental causes for their autism?

Even though my father is a retired engineer and the prevalence of autism among children of engineers and physicists may be higher than in the general population, this makes some sense in my case as there is a history of mental illness, depression, ADHD, learning disabilities and probable autism in my mother's side of the family.  It's possible my mother carried some sort of genes that did not affect her because being a female provided some order of protection and they were passed down to me.  My non-autistic sister may have been afforded the same protection by virtue of her femaleness.

Another point of contention is how much of this is 100% genetic or just a predisposition with environmental causes?  The fact that fraternal twins are no different genetically than regular siblings, yet have higher concordance rates suggests a environmental factor.  Likewise with identical twins who are nearly the same genetically yet don't have a 100% concordance rate.

This would seem to refute the contentions of the neurodiversity movement that autism is the result of naturally occurring random genetic mutations that have evolutionary benefit and thus have stayed in the population.  Of course, I might be going wrong somewhere due to my lack of scientific knowledge and training.

It would also refute the contentions of the anti-vaxers or others who believe something else in the environment, such as pesticides and ultrasounds have caused a widespread autism epidemic and that genetics plays a limited role if any at all.  They say there is no such thing as a genetic epidemic.  That the prevalence would not have gone from 1 in 2500 to 1 in 68 just due to some de novo genetic mutations.  The explanations of some that I have read is that this study was financed somehow by big pharmacy who wants to cover up the fact that they somehow caused the autism epidemic.

I suppose the neurodiversity movement also has an explanation for what is wrong with this study and why the common genetic variation is correct and the limited number of genes that are vulnerable to de novo mutations that disappear from the gene pool have nothing to do with it.  I await their explanation.

10 comments:

Anonymous said...

Dear Jonathan,

This is extremely interesting. I'm not going to respond to all the points, but I will say that I mostly agree with Temple Grandin, and Simon Baron-Cohen in that the traits of Autism include SOME features that were possibly adaptive, once upon a time, but, I would add, that in the past 50-some years, what with all the technological change, and social change, which is now Constant, and getting ever faster, they no longer are beneficial, but are are impediments. I feel almost as though we are being weeded out, of everything, not necessarily as the "conspiracy theorists" say, that "they" are planning this all, step-by-step, but that in a huge system, there are people, especially if they're missing some of the most necessary qualities for modern society, for that , read being highly social, with no common errors, AND flexibility, and fast work speed, whom the increasingly strapped service agencies aren't all that eager to help--they don't know what to do for us; and some of the people who run the organizations, are practically taught to regard some of us as fraudsters, if we say something that isn't in their playbook. I've seen it all too many times. I had somebody tell me to my face that "Asperger's is a childhood disorder; you grow out of it." This was in the late 1990's. I know wishful thinking when I see it. I'm afraid I've gone off on tangents, which seems to also be part of the condition, as well. You can "trim" this post if you want.

lurker said...

I hope those who hear of these studies, realize that autism is genetically caused in different ways for different individuals on the spectrum, although this new study describes a substantial fraction of autistics. Some get it primarily through new mutations, and others through inherited genetic variations. Even if there are some autistic genetic variations that cause advantageous cognitive traits, causing them to be selected to stay in populations, it's still not called for to keep autism the way it is through deciding to ignore the problems of those stuck with disadvantageous forms of autism. That endless talk of autism intellectual advantage has kept me wondering how atypical my autism is, even after I was diagnosed. Empirically, the advantages of autism genetic variations they talk of aren't attainable for all autistics. I heard my father is also an engineer, so I've often wondered why I received such a weak aptitude form of autism. It could be likely that multiple genetic variations determine whether one is autistic and what form, so in families having such autism genetic variations, autism could skip generations, and can have severity/functioning differences between family members. So there just isn't any fairness with this kind of a situation, much less a completely happy and optimistic narrative that is observable in reality.

Brown Ada said...

Impressive analysis on the relation between new genetic study and neurodiversity,and know more about autism itself.-BOC Sciences inhibitor

spinoff said...

There are cases of autism that have clear environmental causes, perhaps as many as 20%. I am talking here about grand prematurity, caesarean section birth, neonatal jaundice, and drugs during pregnancy. The fact that no all of those incidents end up in autism does not mean that they are not the cause, the same happens with tuberculosis and the Koch bacteria.
And there are inherited cases which have clear causes, for example Tuberous esclerosis. You forget about these syndromic cases.

As far as the rest is concerned, besides de novo mutations or multigenetic hereditary causation you must wonder if there is a mechanism of "anticipation" that is something similar as occurs in Fragile X. This will explain why some severe autistic have often fathers which are engineers and other features and why Kanners parents were as he described them.

The only thing that gives autism its unity is its symptoms and underlying neuropsycholoigical deficits.

Ray Rees said...

The neurodiversity paradigm isn't dependent on what causes Autism or any other Neurodivergence. Who cares why I'm Autistic? I still want acceptance of who I am (which includes Autism and other Neurodivergences) regardless of cause.

jonathan said...

Ray, I never said that acceptance (at least to a degree)and finding out what causes autism so we can find the best treatments and hopefully a cure are not mutually exclusive. I don't think most people who want treatments and cures believe this. The reason we should care as to why people are autistic is so that the best treatments and cures can be found someday so that you and I and others on the spectrum don't have to suffer from this debilitating condition.

Contrary to what many in the ND movement say, acceptance and accommodations will never solve everything which is why we need science to try to find some answers on how to best help people such as ourselves.

Ray Rees said...

But I don't want a cure! So, finding out why I'm Autistic or have the other disabilities I do is irrelevant to me.

I really am not a fan of how condescending you are. I am a member of the ND movement, myself. I am also a special education student like you and male-sexed (really, the "they're all female!" argument is WTF). I also suffer from GI problems and have since at least 1 years old when they had cancel my 1st birthday because of it. I have a lot of social anxiety that comes with panic attacks! I know that acceptance and accommodations won't solve everything, but I still want acceptance and accommodations and prefer them to things like ABA.

I don't want to erase your experiences or say you're "wrong" for wanting to not be Autistic, but please don't erase mine or say I'm "wrong" for wanting to remain Autistic. If I say I do not want to be non-Autistic, then I mean it. Social anxiety and GI issues, sure I would like those to go away, but I can be Autistic and not have those things because there are currently existing Autistic people who don't have those things.

jonathan said...

Ray, if you're an adult above the age of consent, not under conversatorship, then I respect your right to reject a non-existent cure. I never tried to be condescending. Many members of ND have never been special education students that I know of. I never said that they were all female, but certainly by a disproportionate amount if you accept the 10:1 ratio usually reported in the literature. That certainly does not apply to ND proponents alleging to be on the spectrum. Acceptance may be good to a certain extent, but to a degree it is not realistic. Accommodations are not really going to solve any of the problems of autism the way ramps for wheel chair users do.

Ray Rees said...

There could be many reasons Autistic females are more likely to be drawn to the neurodiversity movement. Who said the statistics of Autistics in the ND movement had to equal to statistics of Autistics in general?

And that wasn't my point. I support your right to be "cured" if you want that (and I know you do) and it wouldn't cause you/anybody else serious damage. However, as someone who has been in the ND movement since 2012 and does not want to be cured of their Autism, OCD, or ADHD, genetic research has no interest to me.

Your original post was about how does the ND movement reconcile their beliefs with genetic research and my answer as a ND activist is "it doesn't matter." I was strangled at birth by the umbilical cord, but I also have a genetic history of ADHD, dyslexia, OCD traits, and sensory issues. Why I am the way I am is irrelevant to my opinions on the way I am. That's why I said I don't care about genetic research (well, beyond an academic standpoint). I hope that makes sense. :)

DpAutism said...

That you're decision and I respect autistic people decision if they want a cure or not. However, if you guys want to force society to abandon cure and treatment for autism, then you guys are are nothing but selfish.