Estimating masculinity in neurodevelopment disorders

Neurodevelopmental disorders (NDDs) display a striking sex bias, with three males to every one female diagnosed with autism spectrum disorder (ASD) and a two-to-one ratio observed for intellectual disability (ID). This distinct difference in sex has propelled several lines of research investigating the role of sex hormone exposure in relation to NDDs. In particular, digit ratio (ratio of second to fourth digit length) has been utilized as an estimator of fetal androgen exposure, and more loosely as a quantitative measure of masculinity that varies in each sex. However, many of these investigations have been inconclusive, and increasing evidence suggests digit ratio is an inadequate predictor of NDD risk. Emerging research indicates a strong association between facial morphology and NDDs, with evidence suggesting facial masculinity may better capture latent risk factors related to mental disorders.

In this study, we developed an automated facial morphology approach to predict NDD risk as it relates to masculinity and compared it to a standard digit ratio measure. Our method indicated that increasing facial masculinity is associated with increased severity in NDDs. Altogether, these findings suggest that automated facial morphology should be considered as an alternative and preferable measure to digit ratio when assessing risk for NDDs.