Like estrogen loss in older women, decreased levels of testosterone may put aging men at risk for Alzheimer's disease. Researchers from USC found strong suggestions that normal age-related testosterone depletion is one of the important changes that promote Alzheimer's disease in men.
The research shows that testosterone has at least two critical brain functions relevant to Alzheimer's disease, it protects neurons from injury, and it reduces levels of beta-amyloid, the protein widely implicated as a causal factor in the disease. The loss of testosterone with advancing age creates a more hostile neural environment that promotes accumulation of toxic beta-amyloid protein while leaving neurons less able to survive the insult.
I will be writing far more about bioidentical hormone replacment as it is one of my new interests. I am convinced that measuring blood levels of androgens in men and women are really crucial to optimizing health as we age.
JAMA September 22 2004;292(12):1431-2