Men over 64 with low levels of testosterone saw modest improvements in libido and sexual activity when treated with a gel that contains the male hormone, according to U.S. researchers.
The treatments did not significantly improve vitality or walking distance in people tested for those problems, according to the results in the New England Journal of Medicine.
However, researchers did find that when they tested all 790 volunteers to search for improvements in walking and mood - even if men hadn't complained about problems in those areas - they saw significant improvement
The participants were all at least 65 years old, and they all had unequivocally low testosterone concentrations.
"The results don't apply to others," chief author Dr. Peter Snyder at the University of Pennsylvania in Philadelphia told Reuters Health.
Altogether, the researchers tested the gel in seven different trials, and men could participate in more than one. The new report focuses on the trials that assessed the effect of testosterone gel on sexual function, physical function and vitality. Data on its effect on bones and cognitive function, and whether it causes anemia or heart problems, are still being analyzed.
"This is the first time any benefit for those men has been demonstrated. But we still have to wait for the other four trials before we know about most of the benefits of testosterone. And to know about possible risks, we need a larger, longer trial," Snyder said.
"There is one positive finding. The rest is inconclusive," said Dr. Colin Barker, a cardiologist with Houston Methodist DeBakey Heart and Vascular Center, who was not connected to the study.
But Dr. Abraham Morgentaler, director of Men's Health Boston and a urologist on staff at Beth Israel Deaconess Medical Center, called the results "a game changer" that no longer allows critics of testosterone therapy to say the benefits of the treatment are unproven. He is the author of the book "Testosterone for Life," which promotes the therapy.
Morgentaler told Reuters Health that such treatments probably cost $300 to $400 per month if not covered by health insurance.
Testosterone levels decrease with age and have been linked to declines in energy, sexual function and mobility. Past attempts to use testosterone treatment to reverse those problems have produced inconsistent results. Nonetheless, 430 million testosterone prescriptions were written in 2012 - often for middle-aged men - in part because of "Low T" commercials on television.
At a dozen locations in the U.S., half the men were given AndroGel 1 percent to apply to their shoulders each day for one year while the rest used an identical placebo gel. All began the test with blood testosterone levels below 275 nanograms per deciliter. Men at risk for prostate cancer or potential heart problems, two areas of concern for testosterone therapy, were excluded.
Men were included in the sexual function trial if they reported a low sex drive. Volunteers were included in the physical function arm if they had difficulty walking or climbing stairs, although men who couldn't walk at all or had disabling arthritis were excluded. Men were included in the vitality portion if they reported fatigue. Some men were in more than one portion of the study.
The dose of the gel was designed to raise testosterone levels to what is typically seen in healthy men between 19 and 40 years old.
Compared to men in the placebo group, testosterone recipients reported higher sexual desire and increased erectile function.
The benefits were modest and tended to wane with time, noted Dr. Eric Orwoll of the Oregon Health and Science University in an accompanying editorial.
Only when they included men from the other two portions of the trial did the researchers see a significant improvement in physical functioning among the testosterone recipients. "Men who received testosterone were more likely than those who received placebo to perceive that their walking ability had improved since the beginning of the trial," the researchers reported.
Sixteen of the 33 study authors have financial ties to drug companies. Seven of the 16 have worked for AbbVie, which made the testosterone gel used in the study, and the company helped to pay for the test.
SOURCE: http://bit.ly/1WrIe3V New England Journal of Medicine, online February 17, 2016.