Autism: The Literature on Gender Differences

Abstract

Background: Literature on autism spectrum disorders over the years has documented a male-to-female ratio of approximately 4:1. Yet this gender-ratio is now being questioned with studies showing that this ratio may be lower. Factors underlying this male predominance are mostly unknown. Since the majority of published research on autism includes mostly, and in some cases, exclusively males, much less is known about females with autism. 

In this systematic review I examined the available published evidence over 7 years on the possible gender differences in autistic girls and boys.

Methods: A review of the literature was conducted using PubMed with the key words 'autism spectrum disorder' in combination with 'girls and boys' and 'gender differences'. Relevant articles were screened against eligibility criteria leading to 36 final articles which were analyzed in more depth.

Results: Seven key themes on gender differences between autistic girls and boys emerged. These themes include the female camouflage effect, genetic and hormonal mechanisms, autism diagnostic assessment tools which are being increasingly criticized, gender differences in the core diagnostic criteria of autism and differences in comorbidities between girls and boys on the spectrum. 

Conclusion: Managing to understand gender differences better may lead to more accurate and earlier diagnosis of females on the spectrum. Future research should focus on including larger number of females and developing instruments which are better suited to diagnose the female phenotype of autism and to understand the specific needs of females on the spectrum.