In the Baltimore Longitudinal Study of Aging of 574 men, "free" testosterone (or that which is unbound to sex hormone binding globulin) was associated with a decreased risk of Alzheimer's disease.

In another study, researchers in Italy found that sex hormone binding globulin was significantly elevated in men and women with Alzheimer's disease, but total testosterone was normal.

A related editorial by Victor Henderson, MD, MS, and Eva Hogervorst, PhD, at the University of Arkansas for Medical Sciences, raises the question of whether it's men's turn for clinical trails of hormone therapy for the primary prevention of Alzheimer's disease.

Source: 27 January 2004. Neurology