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Male-typic brain anatomy may increase risk for ASD

Biological females with male-typic patterns of brain anatomy exhibited a greater predictive risk for autism spectrum disorders than their peers with characteristically female brain anatomy, according to recent findings.

“Autism spectrum disorder (ASD) is two to five times more common in male individuals than in female individuals,” Christine Ecker, PhD, of Goethe University, Frankfurt am Main, Germany, and colleagues wrote. “While the male preponderant prevalence of ASD might partially be explained by sex differences in clinical symptoms, etiological models suggest that the biological male phenotype carries a higher intrinsic risk for ASD than the female phenotype.”

To assess associations between risk for ASD and normative sex-related phenotypic diversity in brain structure, researchers evaluated a cross-sectional sample of 98 right-handed, high-functioning adults with ASD and 98 matched neurological control individuals. Study participants had an estimated mean age of 27 years and half were male.

Risk for ASD significantly increased with predictive risk for male neuroanatomical brain phenotype. Biological females with a more male-typic pattern of brain anatomy were three times more likely to have ASD than biological females with a characteristically female brain phenotype (P < .001).

Patterns of neuroanatomical variability associated with low or high ASD risk differed between men and women, according to researchers.

Cortical thickness variability in the left and right inferior temporal lobe was an indicator of low or high ASD risk in women, but not in men.

Therefore, while these findings indicated a link between ASD risk and certain patterns of neuroanatomical variability in cortical thickness, patterns are sex-specific, according to researchers.

“No matter how the findings play out concerning other aspects of brain organization, Ecker et al have provided a powerful ‘proof of principle’ study illustrating how a more nuanced understanding of the influences of sex on brain function, one that goes beyond the simple binary categories and incorporates a well-established concept of relative masculinity and femininity in all women and men, should advance our grasp of the etiology of ASD and perhaps of many other brain disorders as well,” Larry Cahill, PhD, of University of California, Irvine, wrote in an accompanying editorial. – by Amanda Oldt

Disclosure: Ecker and Cahill report no relevant financial disclosures. Please see the study for a full list of relevant financial disclosures.