Vitamin T for Sex
Hot, hot hormones.
Oct. 16, 2000 -- Testosterone has been the subject of controversy recently, fueled partly by an April cover story in The New York Times Magazine. Author Andrew Sullivan extolled the effects of the hormone as treatment for his HIV-induced deficiency. Citing bursts in libido, confidence, and energy as a result, he refers to his testosterone injections as "a biweekly encounter with a syringe full of manhood."
Interest rose even higher when, shortly after Sullivan's piece appeared, AndroGel was introduced on the market. The injections used in Sullivan's treatment are painful (he describes the three-inch needle and the resulting trickle of blood) and produce wildly erratic hormone levels (huge burst shortly after the injections, insufficient levels a few days later). But AndroGel, a user-friendly cream containing androgens (the class of steroid hormones to which testosterone belongs), can be absorbed through the skin. AndroGel boasts no-muss, no-fuss easy daily applications that produce far more consistent blood levels of the drug. A cover story in Time Magazine on this development aroused further lively media coverage.
All this buzz about testosterone supplementation evoked a burning question, especially among men of a certain age: Where can guys who are no longer teenagers sign up for this stuff?
The Story Behind the Story
Unfortunately, the optimistic reports about testosterone have omitted some important information, such as the need for painful injections. And they failed to consider the very basic question: Do most men need extra testosterone to reverse some of the typical declines in sexuality as they age?
Interestingly, the answer is no.
Extra testosterone can definitely improve the lives of men with extremely low levels of testosterone due to disease -- say, 5% of normal, due to conditions such as the removal of a pituitary tumor, removal of the testes (in the case of testicular cancer, for example), or in Sullivan's case, HIV. In these cases, the lowered level would likely affect libido. If you were to boost such a man's testosterone levels by giving him supplemental doses of the hormone, you would expect his behavior to return to normal. That was Sullivan's experience, with some healthy placebo effects tossed in on top -- a possibility he barely raises in his piece.
But most men simply don't need AndroGel. Here's why.
Testosterone and the Aging Male
Testosterone levels tend to decline gradually in men, starting in early middle age. The popular perception, and one trumpeted throughout Sullivan's piece, is that this decline is a cause of the typical decrease in energy, edge, and sex drive that often accompanies aging.
But there is simply no scientific data to support a cause-and-effect relationship between the (slow) decline in testosterone experienced during normal aging and a negative impact on libido, sexual performance, or level of energy. Furthermore, even the temporary declines in testosterone experienced by many men during periods of stress (traffic jams, a poor evaluation by a superior) typically do not appear to make any long-term difference in their libido and performance, either.
Behavior Drives Hormones, Not Vice Versa
For argument's sake, let's suppose that for every smidgen of a decline in testosterone, there was a proportional decline in sexual drive, energy, and libido, while for every smidgen of a rise, there was an increase. If that were the case, researchers should be able to select a group of normal, healthy guys for a study, measure their testosterone levels, and show that the men with the higher testosterone levels are more libidinous, sexually active, or more aggressive.
Indeed, some studies have suggested such a correlation. But there turns out to be a confounding factor: Acting aggressively and having sex both raise testosterone levels, so the correlation seems due to behavior driving the hormones, rather than the other way around. This phenomenon has been discussed in many leading texts on the subject.
When experiments control for those factors -- acting aggressively and having sex -- the vast majority of studies, whether of humans or animals, show that individual differences in testosterone levels across the normal range don't particularly predict individual differences in aggressiveness or sexual activity. My own study, "Testicular function, social rank, and personality among wild baboons," published in the journal Psychoneuroendocrinology (Vol. 16, No. 4, 1991), is among the many to have found this.
A Mere 15% of Normal Is Enough