[Fighter365]

The testosterone doses were comparable to those used for testosterone replacement in hypogonadal males. Intracranial, whole brain, gray and white matter of the cerebrum, hypothalamus, and lateral and third ventricle volume changes in the transsexuals were compared with brain volume changes in nine male and six female healthy comparison subjects over a 1-year interval. 

Results: (See Figures 2 & 3) Compared with controls, anti-androgen + estrogen treatment decreased brain volumes of male-to-female subjects towards female proportions, while androgen treatment in female-to-male subjects increased total brain and hypothalamus volumes towards male proportions. (Research Article)

Conclusions: The findings suggest that, throughout life, gonadal hormones remain essential for maintaining aspects of sex-specific differences in the human brain.

Figure 2

Brain volume changes in male-to-female and female-to-male transsexuals. Changes in hypothalamus, total brain, third and lateral ventricle volumes in milliliters (mean change from 0 at first measurement in bars, 95% confidence interval in error bars, individual values in circles) in transsexuals following cross-sex hormone treatment as compared with age- and sex-matched healthy comparison subjects.

Figure 3

Brain volumes in male-to-female and female-to-male transsexuals just prior to treatment. Hypothalamus, total brain, third and lateral ventricle volumes at scan 1 in milliliters (mean volumes in bars, 95% confidence interval in error bars, individual values in circles) in transsexuals as compared with age- and sex-matched healthy comparison subjects (individual value of one control male’s lateral ventricle (62 ml) not printed).

The changes in total brain and hypothalamus volumes following cross-sex hormone treatment in the transsexuals were mirrored by changes in their third and lateral ventricle volumes, i.e. treatment with estrogens and anti-androgens in MTFs increased third and lateral ventricle volumes, whereas treatment with androgens decreased the third and lateral ventricle volumes in FTMs. This suggests that the total brain volume changes are at least in part due to changes in medial brain structures surrounding these ventricles (including, but not limited to, the hypothalamus, which lies in close proximity to the third ventricle). Considering that the effects were not specific for gray (neurons, glia) or white (myelinated axonal fibers) matter suggests that both alterations in nerve cells as well as in axonal fibers may be implicated in the anatomical brain changes following cross-sex hormone treatment in humans. It is not surprising that the influences of sex hormones on the brain were not limited to the hypothalamus, but were also expressed as changes in total brain size. Estrogen and androgen receptor mRNA containing neurons are not limited to the hypothalamus, but are distributed throughout the adult human brain (18).


(18)Simerly RB, Chang C, Muramatsu M & Swanson LW. Distribution of androgen and estrogen receptor mRNA-containing cells in the rat brain: an in situhybridization study. Journal of Comparative Neurology 1990 294 76–95.


Some Information on this. I found some posts about brain changes but noting as in depth as this. 
~Fighter365