Is there a male menopause? Not precisely, but there are certainly significant hormonal changes as men age. A decrease in the level of testosterone in the body begins in the thirties and continues at a relatively constant rate into old age. This is accompanied by other hormonal changes, including a tendency to secrete more adrenal steroids in response to stress.
Although there is no proven relationship between low testosterone and diminished sexual response during aging, it has become clear that a substantial percentage of men over the age of 65 would be diagnosed as testosterone deficient if they were younger.
In addition, a number of research studies have documented that aging brings a decline in sexual activity and quality and quantity of erections, as well as a loss of desire for sexual activity and an increase in the length of time men report being comfortable without sex.
In one study, fewer than 20 percent of men 70 years and older reported consistently adequate erectile function, and nearly 40 percent rated their erectile function as "little or none." In the same study, approximately 15 percent of men age 70 and over reported desire for sex more than once weekly, and 35 percent had no sexual desire. In yet another study, approximately 50 percent of men ages 70-79 reported moderate or complete loss of erectile function, compared with only 25 percent of men 40-49 years of age.
Is a decline in testosterone responsible for these changes? It appears from experiments in a number of animal species that testosterone affects sexual behavior and the ability to have erections, but this has not been proven in humans. Based on animal experiments, low testosterone levels also seem to contributes to age-related changes in fat and muscle. However, only a thorough battery of studies that determine whether or not testosterone replacement slows or reverses these changes will confirm the role the hormone plays in the male aging process.
Testosterone replacement therapy?
In studies so far, the results have been promising. In one study, 80 percent of older men said their libido improved after treatment with testosterone, compared with about 8 percent receiving a placebo. In another trial, of 150 men ages 50-70 treated with another male hormone - dihydrotestosterone - the results indicated that hormone replacement improves early morning erections and the ability to maintain an erection. A few studies suggest that giving testosterone to older men who have low testosterone levels may increase muscle mass, decrease body fat, and improve bone density, but significant effects on strength and endurance with testosterone alone have not been documented.
The adage that "Nothing in life is free" certainly holds true for male hormone therapies. The benefits they promise are accompanied by risks, including:
- Possible prostate enlargement, with obstruction of urine flow or even an increase in cancers.
- Blood cholesterol levels leading to hardening of the arteries (atherosclerosis) and greater risk of heart attacks, strokes, etc.
Studies have not shown whether testosterone actually produces either of the above adverse effects when given to healthy older men with low testosterone levels. A recent study showed that men with adult onset (type 2) diabetes are at greater risk for heart disease if they also have low testosterone levels; so it may be that higher levels of testosterone actually protect men from atherosclerosis. Again, we cannot really assess the risk-benefit ratio for male hormone replacement until we complete more well-controlled studies. Currently, California researchers are treating 300 older men with a testosterone gel to examine the effects on atherosclerosis as well as muscle strength and endurance, fitness, body fat, glucose tolerance, and psychological and sexual function.
And, despite the uncertainties, it is still considered good clinical practice for knowledgeable geriatricians and endocrinologists to treat men, regardless of age, with male hormone replacement when they are clearly testosterone deficient. However, as we noted, many older men with this condition are never diagnosed or treated. If you are experiencing one or more symptoms of low testosterone, you should discuss them with your physician.
Aging alone brings changes
However, you should also keep in mind that aging itself is associated with changes in body composition similar to those observed in younger men with testosterone deficiency. These include:
- Loss of libido and decrease in erections.
- Decreases in lean body mass, muscle strength, and endurance.
- Decreases in bone density.
- Increases in body fat and insulin resistance.
Non-hormonal factors such as nutrition, exercise, oxidative damage, and so on, can also play important roles in the biology of aging. Therefore, testosterone, or even multiple hormone replacement, is not a magic solution that will reverse the effects of aging. Further studies of the risks and benefits of male hormone replacement are needed to clarify the issues we have discussed.
S. Mitchell Harman, MD, PhD, is director and president of the Kronos Longevity Research Institute, a not-for-profit, 501(c)(3) organization that conducts state-of-the-art clinical translational research on the prevention of age-related diseases and the extension of healthier human life. If you would like more about KLRI or its research, please visit their website at www.kronosinstitute.org or call 866-840-1117.
