A new study revealed that testosterone gel can help older men bring back their sex drive and improve their health.

However, the benefits were only modest. In the study published this week in the New England Journal of Medicine, men over 65 years old experienced improved mood and slightly better sexual function. While most of the men experienced the benefits only on the first year of using testosterone gel, researchers say that further investigation might help find out more about the effect of testosterone.

"This was the first time that a trial demonstrated that testosterone treatment of men over 65 who have low testosterone would benefit them in any way," lead author Peter Snyder of the University of Pennsylvania said. "The trial showed that testosterone treatment of these men improved their sexual function, their mood, and reduced depressive symptoms-and perhaps also improved walking."

The U.S. Food and Drug Administration (FDA) does not approve the use of testosterone replacement therapies to just anyone. Using testosterone brings in the risk of increased heart attack and stroke; it should only be given to men with low testosterone levels due to certain medical conditions. They reiterated that men with low hormone levels caused by aging do not quality for it.

The researchers emphasized in their study that the study subjects were men over 65 and have been medically diagnosed with low testosterone.

In their research, the men were either given testosterone gel or a placebo without the hormone and were asked to rub it on their skin for a year. During that period, they were surveyed and asked to take a walking test. They found that the testosterone group experienced a modest improvement in their sex lives and mood, and had better walking strength than the other group. However, they found no significant difference in energy levels.

"The testosterone concentrations in the men in this trial [who got the active treatment] were increased, on average, to just the middle of the normal range for young men," Dr. Snyder said. "Testosterone improved sexual activity, sexual desire and improved erectile function.

During and after the study, some men had heart attacks or were diagnosed with prostrate cancer. However, the rates were similar in both groups. Researchers are unsure which men could benefit over the hormones.

Dr. Eric Orwoll, an endocrinologist at the Oregon Health And Science University, said in an editorial that the findings might be able to help guide doctors and patients.

"I think we can be confident that there is some benefit for some men," he said. "We should not assume that the benefits, lack of benefits, or adverse-event profile observed in these studies would be similar in younger men, men with higher testosterone levels, or those with different demographic or clinical characteristics."