Sex/Gender and Repetitive and Restrictive Behaviors in Autism Spectrum Disorder

The four-to-one ratio of males to females with autism spectrum disorder (ASD) has remained strikingly stable despite evolving diagnostic criteria. As a result of the higher prevalence of ASD in males, females with a clinical diagnosis of ASD tend to be underrepresented both clinically and in research. Given the underrepresentation of females with ASD, the clarification of the nature of sex/gender-specific differences in ASD carries compelling prospects for understanding this heterogeneous condition. In this chapter, we follow Lai et al. (J Am Acad Child Adolesc Psychiatr 54(1), 11–24, 2015) and use the term ‘sex/gender’ to reflect the awareness that the effects of biological ‘sex’ and socially constructed ‘gender’ cannot be easily separated. The present chapter addresses sex/gender differences in restrictive and repetitive behaviors and interests (RRBI), one of the two domains for establishing a diagnosis of ASD. First, we present a review of sex/gender differences in ASD in general, followed by a survey of the sex/gender differential in RRBI over the lifespan and in co-occurring conditions, highlighting the effect of age and IQ. We continue with a survey of differences between males and females in diagnosis ascertainment in ASD, ending with recommendations for future research in the area of sex/gender differences in ASD and repetitive and restrictive behaviors and interests.