The Extreme Male Brain

Interesting article on your front page. Researchers in Australia have also found that high levels of fetal tetesterone is associated with overgrowth in the developing brain and with language disorders.

One problem is that in all these studies not a single case of ASD has been identified, suggesting that 'autistic-like traits' are not the same as autism.

This is consistent with Rutter's two hit mechanism hypothesis which he explained thusly:

"In other words, what is required for autism 'proper' to develop are the susceptibility genes and some other risk factor that could be either genetic or environmental in origin. The implication, if it is a two hit process is that the genes underlying the broader autism phenotype may not be exactly the same as those involved in the transition to the handicapping disorder." Rutter 2006

While affected and one or more unaffected family members have many normal variation traits in common (autistic-like traits), they differ in enormous ways. Normal variation traits are not associated with mental retardation, seizures or structural and gross anomolies in the brain even in autism with normal or high IQ.

Plomin's group in the UK have reported the incidence of autistic-like traits in a large twin sample (thousands of pairs of twins in the UK) being as high as around 10% with 5% of their sample being described as possessing 'extreme autistic traits'.

The current trend that includes the 'Extreme Male Brain' theory is consistent with the trend towards redefining autism as a dimensional trait condition rather than a developmental disorder, threatens to obscure the boundaries between a debilitating neurological disorder and common normal 'traits'.

Very interesting thoughts, RAJ. Figuring out a dividing line between "disabled" and "quirky or eccentric but not disabled" is definitely a challenge, and one I'm sure those working on the DSM-V are having to address since they are providing diagnostic guidelines. I will be interested to see what they come up with!

This sounds so much like my son, especially as noted by RAJ having "autistic-like traits". When my son was about three, we lost our local child psych and had to find a new psychiatrist.After the initial evaluation, the new Dr. said something about my son that has just stuck with me mainly because it seemed so right. He said "It's almost as if he has been lightly brushed with autism. Clearly it's there, but it hasn't seemed to affect him as a whole person". He was just beyond "quirky" and some traits were so mild I was the only one who would pick them up.

At 7 years old now with about 4 full years of OT and Speech therapy under our belts, no one outside our home and special services would guess my son is autistic at all so I am grateful for the "brushing" and not a full-on paint, but it's only because he's been trained to function that he does so well. My son is jokingly referred to by my husband as "all boy" or "all man". It *is* like we took a typical little boy and "blew up" male traits. The child can hardly be found NOT building something, taking something apart, designing something or finding atypical uses for typical things. There's not a mechanical thing that doesn't intrigue or excite him. His interests are far more broad than most Asperger's children but the are a typical set of what I think of as "male" interests. Military. Weather. Transportation. Physics and engineering.

I am also very intrigued by this theory in another way. I'm a woman who has always been told that I "think like a man" and while I am not a professional and am not sure how to pin that statement down, men tell me this all the time, and I figure they're a better judge than I (and not just the mailman, a Clinical Psychologist at USF for example...). I will never know since I did not have an amnio while pregnant with my son if high fetal testosterone was a factor. Still this is a theory that I personally feel makes far more sense than many others because my son does indeed think and act- and more importantly reacts- the way I did as a child. He is like a small copy of me, only male, and add to that male to the Nth degree. Did I inherit a gene or genes that when combined with high fetal testosterone and passed down to my son then resulted in his autism? Do his father and I have a recessive gene that caused this (I will add that in my mind and heart I do not view my son's autism as a disability. I'm sure were his level of functioning lower my perception would be different, but in my case my son is brilliant and difficult. I appreciate the brilliance and work with the difficulties)? My husband says that many "quirks" my son displays he himself displayed as a youngster behaviorally and I know his hyper-sensitivity is a trait I had as a child and to some extent still have now. Could it be something from BOTH of us that was "switched on"?

It seems like an incredibly logical and reasonable explanation, NEARLY to the point of being a forehead slapping "duh!". I believe they have something right or close to right here and I'm excited to see what else this team discovers!!

Something else I wish they'd look in to... is high fetal testosterone found in higher frequency in pregnancies where both parents are highly intelligent? Are more smaller families involved? I am so certain that this is a question of genetics (possibly in combination with other factors). IMO this is some of the best news about autism I've heard yet.

Hi MomofSuperKid, and welcome to IAN.

I am so glad to hear how well your son is doing.

It is clear that the "extreme male brain" theory of autism has resonated with you, based on your experience. Of course, it is only one of many current theories, but it is definitely an intriguing one.

It is also interesting that you note your own personality or way of being seems more "male." I've heard this from at least some mothers of children with ASD, who note things like being socially awkward, loving sci fi/high tech or other "geeky" topics, having no fashion sense, having obsessive interests, or whatnot. It's a bit related to the issue of how we evaluate girls on the autism spectrum. See our article on girls with ASD, here: http://www.iancommunity.org/cs/articles/girls_with_asd

If we better understood girls with ASD, we might also better understand women who are not quite there, but have some ASD-like traits. Of course, the scientific question would be: do these traits occur more often in families of children with ASD than in families that do not have any children with ASD? Are they evenly sprinkled throughout the population, or concentrated in ASD-families?

Researchers are studying such traits, called the "broad autism phenotype," as one window into the genetics of autism. See, for example: http://www.ncbi.nlm.nih.gov/pubmed/19414711?dopt=abstract