Magazine article Clinical Psychiatry News

Fetal Testosterone Theory of Autism Gathering Steam

Magazine article Clinical Psychiatry News

Fetal Testosterone Theory of Autism Gathering Steam

Article excerpt

EDINBURGH -- Why should being male so markedly increase the likelihood of ending up with a diagnosis of an autism spectrum condition?

One explanation gaining increased traction as a result of multiple converging lines of evidence is the fetal testosterone theory of autism, Simon Baron-Cohen, Ph.D., said in the annual Blake Marsh Lecture at the meeting..

Dr. Baron-Cohen is the principal architect of the theory, which asserts that autism is linked to in utero exposure to very high levels of testosterone, with resultant extreme masculinization of the brain and mind. In other words, autism can be thought of as a case of "extreme male brain."

"I think that this hormone--testosterone--at the fetal stage of development, and the genes that regulate it, may be part of the story.

"I don't suggest that it's all of the story because autism is complex and multifactorial. But this may be one of the factors to look at more carefully," said Dr. Baron-Cohen, professor of developmental psychopathology and director of the autism research center at the University of Cambridge (England).

The prevalence of autism spectrum conditions in the general population is about 1%. Classic autism has a male to female ratio of 4:1, whereas in Asperger's syndrome it is 9:1.

Fetal testosterone levels are on average twice as high in males as in females. But levels vary up to 20-fold among male fetuses, he said.

Dr. Baron-Cohen and coworkers are conducting a landmark, ongoing, longitudinal study of 235 typically developing children whose fetal testosterone levels are known because their mothers underwent amniocentesis.

In a recent report, the investigators had parents rate their children for autistic traits at age 8 years using the Childhood Autism Spectrum Test and the Autism Quotient-Children's Version.

They found that the number of autistic traits that a child displayed was positively correlated with fetal testosterone level, independent of sex (Br. J. Psychol. 2009; 100:1-22).

The hallmarks of autism spectrum conditions are social and communication difficulties, narrow interests, and extreme need for routine. Those characteristics can be viewed as extreme manifestations of inherently male interests and behaviors. In studies of spontaneous toy choice that have been replicated hundreds of times throughout the world, psychologists have shown that, given a choice, young boys will more often choose to play with toy vehicles and constructional toys such as Legos, whereas girls tend to be drawn more to dolls and emotional stories about them, Dr. …

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