The Sexual Differentiation of the Human Brain: Role of Sex Hormones Versus Sex Chromosomes.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic, animal, and clinical observational literature without a systematic review protocol
PubMed 30599078 · doi:10.1007/7854_2018_70
What was done
Method and design based on literature review examining animal models and human magnetic resonance imaging studies in individuals with complete androgen insensitivity syndrome (46,XY with female phenotype) to evaluate the relative contributions of sex hormones and sex chromosomes to brain sexual differentiation.
What was found
The abstract reports no numerical values, effect sizes, or sample sizes. It summarizes that neuroimaging shows several female-typical structural and functional brain features in women with complete androgen insensitivity syndrome, supporting a primary role for androgen action, while certain male-typical neural features were also observed, indicating direct sex chromosome gene effects.
Why it matters
This work synthesizes evidence showing that human brain differentiation is not purely endocrine-driven, but instead reflects a multifactorial process involving both organizational sex hormones and sex chromosome genes.
Limits
The abstract contains no primary quantitative data, sample size, or systematic search methodology. In human observational models like complete androgen insensitivity syndrome, separating direct chromosomal effects from estrogenic exposure or female-typical socialization remains challenging.
Cited by
- supports The vast majority of individuals with complete androgen insensitivity syndrome identify as women and are sexually attracted to men.