Sex/gender differences in the human autistic brains: A systematic review of 20 years of neuroimaging research

https://doi.org/10.1016/j.nicl.2021.102811Get rights and content
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Highlights

  • Male-based understanding of autism leads to poor understanding of autistic females.

  • We used a uniquely unbiased search strategy and quantitative evaluation of studies.

  • At least 3 well-powered studies identified sex/gender-modulation of autism effects.

  • No specific brain regions or networks show consistent sex/gender-modulating effects.

  • Future studies require larger sample sizes with more autistic female participants.

Abstract

Our current understanding of autism is largely based on clinical experiences and research involving male individuals given the male-predominance in prevalence and the under-inclusion of female individuals due to small samples, co-occurring conditions, or simply being missed for diagnosis. There is a significantly biased ‘male lens’ in this field with autistic females insufficiently understood. We therefore conducted a systematic review to examine how sex and gender modulate brain structure and function in autistic individuals. Findings from the past 20 years are yet to converge on specific brain regions/networks with consistent sex/gender-modulating effects. Despite at least three well-powered studies identifying specific patterns of significant sex/gender-modulation of autism-control differences, many other studies are likely underpowered, suggesting a critical need for future investigation into sex/gender-based heterogeneity with better-powered designs. Future research should also formally investigate the effects of gender, beyond biological sex, which is mostly absent in the current literature. Understanding the roles of sex and gender in the development of autism is an imperative step to extend beyond the ‘male lens’ in this field.

Keywords

Autism
Neurobiology
Neuroimaging
Brain
Sex
Gender

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