Alzheimer’s disease is characterized by amyloid protein plaques that form in the brain of the afflicted. Testosterone may have a protective effect. An animal study appeared in the Proceedings of the National Academy of Sciences USA (February 1, 2000;97:1202-1205), that looked at the effect testosterone may have on the development of Alzheimer’s disease. Nerve cells from mice and rats produced a harmless form of beta-amyloid protein when in the presence of testosterone. The protein produced in the presence of testosterone is a precursor protein (is turned to other products by the body). Some consider the precursor to actually be beneficial to the health of the nervous system.