PHILADELPHIA, Feb. 18 (UPI) -- A long-term set of studies conducted by researchers at the University of Pennsylvania found testosterone replacement for men over 65 improves sexual function, walking ability, and mood -- results that echo other recent research on the treatment.
The Testosterone Trials is coordinated group of seven trials -- four have not been completed yet -- being conducted at 12 medical centers in the United States to determine the effects of testosterone replacement therapy.
Previous research has shown the treatment can improve cardiovascular health, and low levels of the hormone is linked to conditions such as depression, however its effects on conditions and age groups have been mixed in many studies.
"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," Dr. Peter Snyder, a professor at the University of Pennsylvania, said in a press release. "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."
For trials on testosterone's effect on sexual function, walking ability, and mood, the results of which are published in the New England Journal of Medicine, researchers screened 51,085 men over age 65 for low testosterone and other health criteria, enrolling 790 in the study. The men were treated either with a testosterone gel or placebo gel to use for one year.
Researchers followed up with the men at three, six, nine and 12 months, finding men treated with testosterone gel increased their levels to the mid-normal range for men between 19 and 40 years old.
The treatment was shown to improve all areas of sexual function, including activity, desire and ability to get an erection. For men only enrolled in the physical function trial, treatment did not show significant improvement, but when comparing men in all the trials, more of the men on testosterone improved the distance they walked in six minutes. And while the participants did not report improvements in energy, treatment improved their mood and alleviated depressive symptoms.
While results of the first three of seven trials appear to be positive, researchers remain cautious because of side effects -- adverse health events among participants included heart attack, stroke, and other cardiovascular and prostate conditions.
Dr. Eric Orwoll, a professor of medicine at Oregon Health and Science University, wrote in an editorial published in the New England Journal of Medicine that the study is significant because it shows some success with the treatment. He adds, however, that more research is necessary because the treatment's effects were relatively modest and not nearly enough is known about the potential side effects.
"There is considerable controversy about possible adverse effects of testosterone therapy in older men, and these studies do not resolve this controversy," Orwoll wrote. "Although there were minor effects on hemoglobin and prostate-specific antigen levels, and, reassuringly, no apparent major toxic effects, larger and more extended trials would be needed to determine whether therapy has negative effects on outcomes such as prostate or cardiovascular health."