Posted this on my blog, thought it may be of interest here....
I'm in the process of finishing up research on my neuro paper, which focuses on dimorphism of the human brain between the sexes, with a potential tie-in to the biological basis of transsexuality. Interestingly, one item I uncovered relates to trans scientific research. One study found that, over time, administration of masculinizing or feminizing hormones to genotypical males and females seeking to change to their target, i.e. opposite, sex, does in fact physically alter brain size by volume measurements. For Male to Female trans, the brain feminizes and becomes smaller, while for Female to Male, it increases in size. What seems known are these purely volumetric statistics; what are not known is if a dramatic increase in estrogen or testosterone leads to a "re-wiring" of the brain and a differentiated brain functionality, as identified in numerous studies between males and females.
But here's my curiosity: although there truly is a dearth of scientific research with regard to the constituent causes of transsexuality, those studies that do exist - including the recent androgen receptor study completed last October - utilize transsexual individuals already affected by hormone therapy. If hormone therapy has been found to affect brain size by masculinizing or feminizing the brain to typical measurements, then this would seem to devaluate all studies of brain differentiation in trans folk, as performed in today's laboratories. What really needs be done is to establish a proper research group prior to the beginning of HRT, conduct brain volume analyses and other measurements pre-HRT, and then conduct the same measurements at definitive time periods into HRT therapy. Only in this light can we accurately measure any potential brain volumetric differences in trans-identified persons relative to their projected target sex.
While I am a big believer in the theories of biological causes of transsexuality, given that hormone administration has been found to alter brain size from masculinization to feminization and vice-versa, I must view current research methods as potentially fatally flawed in this regard. Clearly, greater research is needed in this area, with the stated goal of developing a research population as early into the process as possible.
Interesting creatures, we TG/TSs' are.... 😉