Study Questions Large Head Size in Autism

Two new studies raise questions about one of the most frequently reported biological signatures of autism: a larger-than-normal head.

Leo Kanner's original description of autism noted this so-called macrocephaly, and dozens of studies have since reported that children with autism show accelerated head growth in their first two years of life.

Most of this work relied on biased control samples, according to an analysis of 34 studies, published 23 May inBiological Psychiatry.

Only 7 of the 34 studies are “methodologically robust,” meaning that they followed the same children over time and relied on controls recruited from the same geographic region as the participants with autism. Four of the seven studies found significantly faster head growth in those with autism compared with controls, but three did not.

“It was a bit of a shock to me,” says lead investigator Armin Raznahan, a staff scientist at the National Institute of Mental Health’s Child Psychiatry Branch. “Like everyone else, I’ve written papers that include the sentence: ‘Early brain overgrowth is one of the best replicated findings in autism.’”  

Read more at... 

SFARI.org, June 2013. 

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