" Whereas women experience dramatic fluctuations of estrogen followed by a plummeting of estrogen that remains plateau and very low for the rest of their lives during perimenopause, men experience a very gradual loss of testosterone that begins in the late 50s and early 60s. There are rather large differences among men. Some men experience decreases in testosterone, while others experience only subtle decreases. Some data shows that men who maintain higher levels of testosterone as they age have higher brain functioning and brain structure and a lower risk of Alzheimer’s. That’s of interest to us because testosterone is aromatized—it’s converted to estrogen in people with high levels of testosterone, so some of the data’s very consistent with the idea that estrogen can be neuroprotective. "