Testosterone May Prevent the Onset of Alzheimer’s Disease

A professor at The University of Texas Medical School at Houston has released a study determining how the male hormone testosterone, either alone or in combination with estrogen, prevents one of the key biochemical abnormalities occurring in Alzheimer’s disease.

The study, partly funded by the Chicago-based Alzheimer’s Association, was reported in the Proceedings of the National Academy of Sciences.

Dr. Sozos Papasozomenos, a professor of pathology and the director of autopsy services at the UT-Houston Medical School, reported that testosterone, or testosterone plus estrogen, but not estrogen alone, prevents the biochemical aberration that leads to the formation of neurofibrillary tangles, a hallmark of the Alzheimer’s-afflicted brain.

The tangles are comprised of filaments primarily made up of a brain protein called "tau." When tau bundles together in this abnormal manner, Dr. Papasozomenos said, the protein clumps possess an overabundance of phosphate molecules. The production of these molecules is regulated by the body’s response to stress – too much stress, and the body produces too many phosphate molecules. However, the body has a natural defense against stress – testosterone.

The study used 75 female rats, which had had their ovaries removed to ensure that their bodies were not producing estrogen naturally. They were injected with estrogen, testosterone, both, or neither, then put into an incubator and exposed to higher-than-normal temperatures for short periods of time, which caused the rats to become stressed. The rats receiving testosterone alone or in combination with estrogen showed no symptoms of the brain changes that signal the onset of Alzheimer’s.

While estrogen has been studied for its potential benefits in delaying or preventing Alzheimer’s disease, testosterone has been largely ignored, said Dr. Papasozomenos. This widespread neglect to study testosterone as a possible benefit has resulted in a poor understanding of the hormone, which, he believes, has been unfairly mischaracterized as a trigger of aggressive behavior.

"Testosterone has a bad reputation, which it really doesn’t deserve," he said. "In fact, I believe this study serves as the basic research needed to justify a clinical trial of using testosterone in people who are at high risk of developing Alzheimer’s and other dementias."

Dr. Papasozomenos said his findings suggest that giving testosterone to aging men, or to postmenopausal women in combination with estrogen, may help delay, prevent and/or treat Alzheimer’s disease.

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©2006 Texas Medical Center

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