Why are autism spectrum conditions more prevalent in males?
Level 5 - mechanism / opinion, no new human data
Narrative review and theoretical synthesis without systematic search or new empirical data.
PubMed 21695109 · doi:10.1371/journal.pbio.1001081
What was done
This narrative review updates the Extreme Male Brain (EMB) and Empathizing-Systemizing (E-S) theories to evaluate biological mechanisms underlying the male prevalence bias in Autism Spectrum Conditions (ASC). The authors examine the role of fetal testosterone (fT) alongside alternative hypotheses, including sex chromosome effects (X and Y chromosome theories) and reduced autosomal penetrance, drawing on longitudinal amniocentesis cohorts followed up to age 10, current hormone measurements, and genetic association studies of sex steroid pathway SNPs.
What was found
The abstract reports no quantitative values, sample sizes, or effect estimates. It notes that none of the discussed biological theories have been fully confirmed or refuted, but concludes that converging lines of evidence from longitudinal developmental studies, hormonal assessments, and sex-steroid pathway genetics provide growing support for the fetal testosterone hypothesis.
Why it matters
This paper organizes endocrinological, genetic, and neurodevelopmental hypotheses into a unified framework to guide research into the biological drivers of the male sex bias in autism.
Limits
As a narrative review, it lacks a systematic search protocol, meta-analytic pooling, or formal risk-of-bias assessment. The abstract reports no empirical numerical data, and the authors explicitly note that the etiology is multifactorial and that none of the candidate mechanisms have been definitively established.
Cited by
- context Simon Baron-Cohen's autism research associates autism with hyper-development of the left cerebral hemisphere, explaining its higher prevalence in boys.