Wednesday, September 28, 2011

John Robison's interesting theory on male/female sex ratios in autism

I see that one of my favorite scientific reviewers of both public sector research grant proposals for autism research and proposals by people seeking funding from autism speaks is at it again. John Elder Robison is curious as to why the ratio of autistic males to autistic females is so high.

As regular readers of my blog know,i discussed this in a recent blog post.

Robison in the past has made questionable statements about causes of increases in autism prevalence, for example suggesting that a good portion of the increase could come from the rare condition chronic disintegrative disorder. He has also suggested studying geek success as a legitimate scientific endeavor to help ameliorate the problems of autistic persons.

When I find it inconceivable that Mr. R can't top himself in his brilliant theories and suggestions to help understand and help those with autism, he never ceases to amaze me with what has to be his most astute observation ever. On speculating as to why the ratio of autistic males to autistic females is so high Mr. Robison writes:

One explanation is that some parents have a son with autism and stop having children. So the girls that might even the male/female ratio are never born. I think that explanation may be true today, but what about the ages before modern birth control?

That's an interesting idea, however, I do have one question. Previously in his post Robison conceded that there is a 50/50 chance of a baby being born either a boy or a girl. So I wonder why parents could not have a daughter as their first born with autism and then stop having other children after their daughter is born? In that case the ratio of autistic females to males would be 4:1 or higher.

If Robison's theory were to have any credibility it would mean that at least four times as many boys are born than girls. If that were true there would be plenty of typical males who would have trouble finding mates the way autistics do and not as many babies would be born and over population would not be such a problem. Yet he contradicts this notion previously in the post by saying just as many males are born as females.

I would be very interested in hearing Robison's explanation as to why this theory would only apply to first born sons rather than first born daughters, must be a doozy.

I can't think of how well I'll sleep at night, as a former taxpayer, knowing that someone who is so brilliant is reviewing government research grants to decide what sort of autism research is funded at my expense.

The persons who donated money to autism speaks with autistic children who will never make a six figure income, get married or write a best selling memoir will certainly be secure in knowing that an individual that thinks things through so clearly is working so hard to see the right research is funded by this stellar organization.

The rumor mill has it that now that the combating autism act will be renewed after the formality of Obama signing the bill into law that Mr. Robison will be the third public member on the spectrum, alongside Stephen Shore and Ari Ne'eman on the IACC. I wonder what other brilliant suggestions he will make in this capacity. I'm wondering if he can possibly top this one, that would seem quite a formidable task.

He concludes the post by saying:

It would be very interesting to see a study that addressed this question. Perhaps a grad student somewhere will read this, and bring a research proposal to our next review meeting . . . .

Stranger things have happened.

Yes, I do agree with Robison here. Stranger things have happened. Like a certain high school dropout I know getting to review scientific grant proposals along with all of these M.D. and Ph.D. scientists.

Addendum: I see that autism speaks has posted Mr. R's post on their blog they have certainly once again shown their credibility as a fund raising organization.


SM69 said...

The argument put forward to account for the boy:girl ASD sex ratio is illogical.

There are on average slightly more boys than girl in the general population, in fact 105 boys for 100 girls, the reason is that the y chromosome is smaller and that male spermatozoids are moving faster, therefore will have a greater chance to fertilise an egg.

But for the sake of argument, let's say it’s a 50:50 boys to girls ratio in the general population. If the chances to present with autism (as we measure it today), were the same between boys and girls, it would not change anything at all, whether the first born child is a boy or a girl, irrespectively or not of the parent’s decision to stop having kids afterwards. This is a simple probability consideration.

My preferred explanation and I believe I have some evidence in support to this (as others have, Gillberg and Kopp-see below), is that there is a significant under diagnosis of ASD in girls, because they tend to be less aggressive and have developed more sophisticated social presentation that hides more effectively their difficulties. But the very same issues in terms of actual understanding of relationship, self awareness, short-terms memory, decision taking, appear to be present.

I believe the health and education authorities are not particularly motivated to pick up these girls- after all having a diagnosis usually implies more expenditure.

Girls with social deficits and learning problems: Autism, atypical Asperger syndrome or a variant of these conditions

Svenny Kopp and Christopher Gillberg

Volume 1, Number 2, 89-99, DOI: 10.1007/BF02091791

Six girls aged 6–10 years meeting criteria for autistic disorder are presented. They were all high-functioning in that they had IQs in the 60–100 range and spoke in complicated sentences. Their clinical picture had not led a variety of specialists to consider an autism diagnosis before age 6 years in spite of the fact that they had shown mild motor delays, uncharacteristic developmental deviance and social, communicative and imaginative deficits already before age 2 years in all cases. It is suggested that the autism phenotype might be different in girls as compared with boys. It is further speculated that if female cases such as those described — and others given a whole host of different diagnostic labels — were only considered for an autism diagnosis, the high male:female ratio traditionally encountered in autism might drop considerably.

jonathan said...

i don't think Gilberg's study would explain a 4:1 ratio let alone the approximately 10:1 ratio that I seem to remember is reported in the literature for those who are higher functioning.

One problem with your argument and Gilberg's is that similar ratios have been reported in other conditions that don't have the same social problems of autism such as dyslexia, ADHD and stuttering.

SM69 said...

This argument would not explain any specific ratio, it only provides a possible explanation for such a high boy:girl distortion.

The ratio of 10:1 tends to be more for AS than ASD or autism and I would actually argue that it is possibly even more likely to miss out the girls the higher functioning one is- same argument.

ADHD ratio male distortion could also be explained with the same line of argument- less aggression, fitting better in the system, therefore falling through the net.

However, yes I agree one cannot hide stuttering, so the male excess must be for that condition at least a true biological feature.

I still think girls in ASD are under diagnosed.

SM69 said...

Just wanted to add along these lines of arguments, I recently heard John Morgan from the Yorkshire Centre for Eating Disorders explaining that 1/5 of anorexic girls have ASD (that was undiagnosed)- He discussed the concept between autism and anorexia nervosa and had some good points as to why autism can account for these eating issues, central coherence, Theory of Mind and executive functioning.

PonderingMind said...

Studying "geek success" doesn't ameliorate autism; it supposedly helps your self-esteem if you're autistic.

Anonymous said...

How much of it is genuine, how much is under-diagnosis of girls, and how much is *over-diagnosis* of boys?

After all, it's usually harder to get away with "I don't have to care what she thinks because I'm male, she has to care what I think because she's female" these days than it was in the past. How many guys with this attitude now blame their sexism on autism/Asperger's and phrase it as "I don't have to care what she thinks because I'm Autie/Aspie, she has to care what I think because she's NT"?