Testosterone reduced the vascular benefits of Estrogen (conjugated equine Estrogen) in female rat model. Testosterone is seeing widespread use in women with very little positive data. In fact, the majority of data points to poor metabolic effects and poor outcomes.
This was the WHI review of data as it pertains to dementia and cognitive decline in women. The take home here is that the data provides little evidence for premarin with or without medroxyprogesterone acetate in > 65 for prevention of dementia. However, this is in women > 65 and studies show that younger women do indeed receive benefit, especially in those with early ovary removal. Another point here, MPA (medroxyprogesterone acetate) increases cognitive decline. Just don't take MPA, it is a bad drug all the way around!