Testosterone May Protect Against Alzheimer's
Researchers Caution: Too Early to Recommend Testosterone Therapy for Prevention of Alzheimer' Disease
The findings are published in the Jan. 27 issue of the journal Neurology. In the same issue, researchers from Italy reported that lean male and female Alzheimer's patients had low levels of free testosterone when compared with the control group. Editorialists question whether it is time for testosterone prevention trials in men.
More than 1.7 million prescriptions for testosterone were written in the United States in 2002, representing a 30% increase over 2001 and a 170% increase over 1999, according to figures from the National Academy of Sciences' Institute of Medicine. Older men are increasingly taking the hormone in an effort to stop the clock and prevent conditions associated with aging, even though the medical evidence for this is weak.
Last November, an Institute of Medicine task force came out against large-scale testosterone prevention trials similar to the estrogen replacement therapy trials in women. Instead, the group recommended smaller trials involving only older men who had been diagnosed with low testosterone and who are not at high risk for prostate cancer.
Just as long-term estrogen replacement therapy in older women has been linked to an increased risk of breast cancer, there are concerns that men who take testosterone may be increasing their prostate cancer risk.
Alzheimer's expert Samuel Gandy, MD, PhD, says the hope is that scientists will develop a "designer" testosterone that would target the brain and not affect other organs, in the same way the designer estrogen-like compounds, such as Raloxifene (Evista), targets the bones to prevent osteoporosis.
"Theoretically we could develop a designer estrogen or testosterone that could be protective against dementia," he says.
The Alzheimer's Association spokesman, who runs the Farber Institute for Neurosciences at Philadelphia's Thomas Jefferson University, says the long-term risks vs. benefits of taking testosterone to prevent dementia will not be known until clinical trials are completed.
"Until that happens there is no medical justification for taking testosterone to lower the risk of Alzheimer's," he says. "The data just aren't there to support that as a recommendation."