PHILADELPHIA -- As men age, their testosterone levels decrease, but prior studies of the effects of administering testosterone to older men have been inconclusive. Now, research shows that testosterone treatment for men over 65 improves sexual function, walking ability and mood, according to a study published in the New England Journal of Medicine by team researchers from the Perelman School of Medicine at the University of Pennsylvania, and twelve other medical centers in the United States, in partnership with the National Institute on Aging.
Researchers conducted The Testosterone Trials (TTrials), a coordinated group of seven trials, and have analyzed the results of the first three - Sexual Function, Physical Function and Vitality. They found that testosterone treatment increased the blood testosterone level to mid-normal for young men. Testosterone also improved all aspects of sexual function, including sexual activity, sexual desire and the ability to get an erection. Testosterone treatment did not significantly improve distance walked in six minutes when only men enrolled in the physical function trial were considered, but did increase the distance walked when all men in the TTrials were considered. The treatment did not improve energy but did improve mood and depressive symptoms.
"The results of the TTrials show for the first time that testosterone treatment of older men who have unequivocally low testosterone levels does have some benefit," said the principal investigator of the TTrials Peter J. Snyder, MD, a professor in the Division of Endocrinology, Diabetes and Metabolism. "However, decisions about testosterone treatment for these men will also depend on the results of the other four trials - Cognitive Function, Bone, Cardiovascular, and Anemia - and the risks of testosterone treatment."
In 2003, the Institute of Medicine reported that there was insufficient evidence to support any beneficial effect of testosterone in such men. This report was the impetus for TTrials, which are now the largest trials to examine the efficacy of testosterone treatment in men 65 and older whose testosterone levels are low due seemingly to age alone. TTrials researchers screened 51,085 men to find 790 who qualified with a sufficiently low testosterone level and who met other criteria. The men enrolled were randomized into two groups: one to take a daily testosterone gel and the other a daily placebo gel, for one year. Efficacy was then evaluated at months three, six, nine and 12. Sexual function was assessed by questionnaires; physical function was measured by questionnaires and the distance walked in six minutes; and vitality, mood and depressive symptoms were also evaluated using questionnaires.
Across the three trials, adverse events including heart attack, stroke other cardiovascular events and prostate conditions, were similar in men who received testosterone and those who received placebo. However, the number of men in the TTrials was too small to draw conclusions about the risk of testosterone treatment. Snyder added, "a larger and longer trial is needed to assess the risks of testosterone treatment."
The TTrials were conducted at 12 additional medical centers across the country including Albert Einstein College of Medicine, Baylor College of Medicine, Brigham and Women's Hospital, Harbor-UCLA Medical Center, University of Alabama at Birmingham, Northwestern University Feinberg School of Medicine, Puget Sound Health Care System, University of California at San Diego School of Medicine, University of Florida School of Medicine, University of Minnesota School of Medicine, University of Pittsburgh Graduate School of Public Health, and Yale School of Medicine.
The Testosterone Trials were supported by a grant from the National Institute on Aging (NIA), National Institutes of Health (U01 AG030644). The TTrials were also supplemented by funds from the National Heart, Lung and Blood Institute, National Institute of Neurological Diseases and Stroke, and National Institute of Child Health and Human Development. AbbVie (formerly Solvay and Abbott Laboratories) also provided funding, AndroGel, and placebo gel.
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