The results of these studies indicate that testosterone treatment in older men with low testosterone levels may offer some benefits. Many men over 65 with low testosterone levels say that their sense of well-being, not to mention sexual function, is no longer the same as before. The Emmelot-Vonk study, published in January. Small randomized trials suggest that testosterone therapy may improve depressive symptoms in men with persistent depressive disorder (dysthymia) late in life (20).
Aging in men is also associated with a reduction in serum testosterone, increasing the possibility that the decrease in the concentration of circulating testosterone contributes to age-related cognitive decline. It has been hypothesized that this decrease in testosterone can result in several factors, such as decreased sexual function, energy, mood, and clarity of thought, as well as anemia and bone fractures. Until the first year of the trials ended, neither the participants nor the researchers knew which men were receiving the placebo or testosterone gel. Testosterone administration also moderately improves aerobic capacity and mitigates the age-related decrease in maximum oxygen consumption (VO2peak).
The results of an extensive RCT in men with glucose tolerance problems or type 2 diabetes (trial with type 2 diabetes) suggest that testosterone treatment given in conjunction with a lifestyle program is more effective than the lifestyle program alone in reducing the proportion of men with type 2 diabetes (2). However, in men who used testosterone and who had reported memory problems at the start of the study, there were no improvements in memory or cognition. Testosterone treatment increases spontaneous sexual thoughts, attention to erotic cues, the duration and frequency of nighttime penile erections, and ejaculation volume. Among men who used the testosterone gel, there were statistically significant improvements in bone density in the lumbar spine and hip and in bone strength.
The studies are collectively called testosterone trials (TTrials) and compared a testosterone gel, AndroGel, with a placebo. In 2003, a panel from the Institute of Medicine concluded that there was insufficient evidence to support the benefits of testosterone in older men and recommended further research. These results may have clinical value, and testosterone treatment could be used to increase hemoglobin levels in men over 65 with unexplained anemia and low testosterone levels. Some trials have seen greater improvement in measures of insulin resistance with testosterone treatment in men with type 2 diabetes or metabolic syndrome than with placebo (but testosterone treatment has not consistently improved glycemic control).
However, large, long-term studies have not been conducted to determine if testosterone treatment actually helps treat these conditions. Dr. Emmelot-Vonk and his colleagues gave testosterone supplements (or an inactive placebo) to 237 healthy men aged 60 to 80 years. Testosterone may also reduce the propensity for falls due to its effects on muscle strength and reaction time.