Testosterone gel improves sex drive in older men
A new study offers the first clear evidence that testosterone treatment for men 65 years and older can improve mood and sex drive.
The results, published in a paper in the New England Journal of Medicine, are from the first three of seven trials in a longterm study called the Testosterone Trials, or the TTrials. The studies are testing the effect of testosterone gel compared with placebo, and changes in sexual function, vitality, mood, physical function, walking speed, and walking distance.
Researchers found that testosterone treatment increased the blood testosterone level in the men 65 and older to levels comparable 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,” says Peter J. Snyder, a professor at the University of Pennsylvania and lead author and principal investigator of the TTrials. “However, decisions about testosterone treatment for these men also will depend on the results of the other four trials … 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.
“Previous testosterone trials in older men yielded equivocal and inconsistent results,” says Jane A. Cauley, a professor at the University of Pittsburgh and study coauthor. “We showed that testosterone improved men’s impression that their sexual function and walking ability had improved, suggesting that these effects are clinically important.”
But is it safe?
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 apply the daily testosterone gel and the other a daily placebo gel for one year. The results were 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 also were 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, which the researchers say would require a larger and longer trial.
“A larger and longer-term trial will be needed to have more definitive results regarding safety,” says Marco Pahor, director of the University of Florida Institute on Aging and a coauthor of the paper. “However, this trial did not confirm earlier, smaller trials that raised serious concerns regarding cardiovascular safety.”
The TTrials were conducted at 11 additional medical centers across the United States and supported by the National Institutes of Health.