Testosterone is a vital sex hormone that plays an important role in puberty. In men, testosterone not only regulates sex drive (libido), it also helps regulate bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm. Testosterone isn’t exclusively a male hormone—women produce small amounts as well.
As men age, they often produce somewhat less testosterone, especially compared to years of peak testosterone production during adolescence and early adulthood. Normal testosterone production ranges widely, and it is unclear what amount of decline or how low a level of testosterone will cause adverse effects.
In recent years, the popular press has increasingly reported about “male menopause,” a condition supposedly caused by diminishing testosterone levels in aging men. There is very little scientific evidence that this condition, also known as andropause or viropause, exists. The likelihood that an aging man will experience a major shutdown of testosterone production similar to a woman’s menopause is very remote. In fact, many of the changes that take place in older men often are incorrectly attributed to decreasing testosterone levels. For instance, some men experiencing erectile difficulty (impotence) may be tempted to blame it on lowered testosterone, but many cases of erectile problems are due to circulatory problems.
For men whose bodies make very little or no testosterone, testosterone replacement may offer benefits. FDA-approved testosterone drugs come in different forms, including patches, injections, and topical gels. Men whose testes (the reproductive glands that make testosterone and sperm) have been damaged or whose pituitary glands have been harmed or destroyed by trauma, infections, or tumors may also be prescribed testosterone. Treatment with testosterone drugs can help men with exceptionally low testosterone levels maintain strong muscles and bones and increase their sex drive. It is unclear if men who are at the lower end of the normal range for testosterone production would benefit from treatment.
More research is needed to learn what effects testosterone drug therapy may have in healthy older men without these extreme deficiencies. NIA is investigating the role of testosterone therapy in delaying or preventing frailty and helping with other age-related health issues. Results from preliminary studies involving small groups of men are inconclusive. Specifically, it remains unclear to what degree testosterone supplements can help men maintain strong muscles and sturdy bones, sustain robust sexual activity, or sharpen memory.
There are also concerns about the long-term, harmful effects that testosterone drugs might have on the aging body. Most epidemiological studies suggest that higher natural levels of testosterone are not associated with a higher incidence of prostate cancer—the second leading cause of cancer death among men. However, scientists do not know if taking testosterone drugs increases men’s risk for developing prostate cancer or promoting the growth of an existing tumor. There is also uncertainty about effects of testosterone treatment on the cardiovascular system in older men, especially men with mobility limitations and other diseases. Future studies will address this issue to ensure that older men receiving testosterone treatment are not exposed to unnecessary risks.
The bottom line: there is no scientific proof that testosterone treatment in healthy men will help them age better. Until more scientifically rigorous studies are conducted, it is not known if the possible benefits of testosterone therapy outweigh any of its potential risks. NIA continues to conduct research to gather more evidence about the effects of testosterone treatment in aging men.