Men over 65 who had their testosterone levels reset to those of much younger men didn't walk any faster. But they had more spring in their step, better erections, and a keener interest in sex than men who didn't get testosterone supplements.
This set of trials, underwritten by the National Institute on Aging and several other national institutes, also found no increased risk of stroke or heart attack in those taking testosterone. At the same time, however, the study's authors acknowledged that these trials could not have detected anything short of a major jump in cardiovascular events.
In a trial published Wednesday in the New England Journal of Medicine, researchers compared the mood, physical vitality and sexual vigor of older men who got testosterone supplementation for a year with those of their peers who did not. All the men started the trials with testosterone levels of 275 ng per deciliters -- levels that were pretty low for men over 65 (only about one in five men screened for inclusion in the trial qualified) and "unequivocally low" compared to levels typically seen in healthy young men.
The idea of The Testosterone Trials was to gauge whether men whose testosterone levels are "low for no apparent reason other than age" will benefit by having those levels boosted pharmaceutically. The benefits they found were most apparent in the realm of sexuality, and either modest or not evident on broader measures of health and functioning.
For a year, men in three groups had their testosterone levels boosted to levels typical of a man 19 to 40 years old, using a product called AndroGel (whose maker, AbbVie, provided study funding and donated product, as well as consulting fees to four of the study's 33 authors). A fourth group got a placebo product, and served as a comparison group for the testosterone-supplemented men on sexual function, vitality and physical well-being.
Men whose testosterone rose most saw the greatest increases in sexual interest and performance, as measured by a daily questionnaire about psychosexual health.
After three months of getting testosterone, the men in the trial's sexual function arm reported a roughly 60% jump in their sexual activity. That level stayed at more than 50% above their baseline levels until roughly month nine, at which point the increase in sexual activity over baseline slumped to about 20%.
On other measures, compared to men getting the placebo product, those who got the testosterone supplement reported increased sexual desire and better erectile function.
Men who got testosterone showed no less evidence of fatigue. But they scored slightly higher than men who got a placebo on a questionnaire measuring their sense of vitality, and reported slightly lower depression symptoms. And at the end of the trial, men who got testosterone were more likely than men who didn't to report their energy was better.
The effects of testosterone on mens' physical function were more mixed. In the subset of men who were specifically compared on physical function, testosterone didn't perform any faster on a six-minute walking test. But by a broader measure that included a questionnaire about physical function, they did a little better.
When all the trial's participants were tested on walking speed, however, more of those who got testosterone improved than did those who got a placebo. And despite evidence to the contrary, men on testosterone were more likely than those who got a placebo to perceive that their walking had improved.
In addition to the National Institute on Aging's support, the Testosterone Trials were also funded by the National Heart, Lung and Blood Institute, the National Institute of Neurological Disorders and Stroke, and the National Institute of Child Health and Human Development.
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