In a multi-institutional study to understand the effects of testosterone treatment in men age 65 and older, researchers found improved sexual function, walking ability and mood. The study, conducted by 12 institutions including Baylor College of Medicine in partnership with the National Institute on Aging, appears today in the New England Journal of Medicine.

“This is the largest to date and most rigorously conducted trial evaluating the benefits of testosterone replacement in older men with low testosterone levels,” said Dr. Glenn Cunningham, distinguished professor emeritus in the Department of Medicine - Endocrinology at Baylor. Cunningham served as the principal investigator for the Baylor site and as a member of the steering committee for the trials. “However, our trial is not large enough nor did it last long enough to determine potential risks of testosterone replacement.”

As men age, their testosterone levels decrease, and previous studies on the effects of testosterone treatment in older men have been inconclusive. Researchers studied testosterone treatment in men 65 and older whose testosterone levels were low due to age alone. The 790 men enrolled in the trials were randomized into two groups – one applying a testosterone gel daily and the other applying a placebo gel daily.

For this study, researchers conducted a coordinated group of seven trials and have now published the results of the first three: sexual function, physical function and vitality. They found that testosterone treatment increased the blood testosterone level to mid-normal for young men and improved all aspects of sexual function, including sexual activity, sexual desire and the ability to get an erection. When researchers evaluated only men enrolled in the physical function trial, the treatment did not significantly improve distance walked in six minutes, but when all men in the trials were considered, it did show an increase in distance walked. The study also showed that the treatment improved mood and depressive symptoms.

Researchers concluded that a larger and longer study needed to be conducted to understand the risks of the treatment.

The Perelman School of Medicine at the University of Pennsylvania was the coordinating site for the study. Other institutions taking part in the study included Albert Einstein College of Medicine, Brigham and Women’s Hospital, Harbor-UCLA Medical Center, University of Alabama at Birmingham, Northwestern University Feinberg School of Medicine, Puget Sound Health Care System, University of California at San Diego School of Medicine, University of Florida School of Medicine, University of Minnesota School of Medicine, University of Pittsburgh School of Public Health, and Yale School of Medicine.

The Testosterone Trials were supported by a grant from the National Institute on Aging (NIA), National Institutes of Health (U01 AG030644). The TTrials were also supplemented by funds from the National Heart, Lung and Blood Institute, National Institute of Neurological Diseases and Stroke, and National Institute of Child Health and Human Development. AbbVie (formerly Solvay and Abbott Laboratories) also provided funding, AndroGel, and placebo gel.