Parent-Endorsed Sex Differences in Toddlers with and Without ASD: Utilizing the M-CHAT

Abstract

Sex differences in typical development can provide context for understanding ASD. It has been suggested that ASD could be considered an extreme expression of normal male, compared to female, phenotypic profiles. In this paper, sex-specific M-CHAT scores from N=53,728 18-month old toddlers, including n=185 (32 females) receiving an ASD diagnosis, were examined. Results suggest a nuanced view of the “extreme male brain theory”. At an item level, almost every male versus female disadvantage in the broader population was consistent with M-CHAT vulnerabilities in ASD. However, controlling for total M-CHAT failures, this male disadvantage was more equivocal and many classically ASD-associated features were found more common in non-ASD. Within ASD, females showed relative strengths in joint attention, but impairments in imitation.