Experts have long assumed that as a man’s testosterone level declines, so does his sex life. But a new study suggests the reverse may be true.
“Most people in or out of medicine assume that a lowered serum testosterone may cause reduced sexual activity. But our study questions, if not fully refutes, that assumption and suggests it is the other way around,” said Dr. David Handelsman, a researcher at the University of Sydney, in New South Wales, Australia.
And skyrocketing sales of testosterone supplements are being fueled by that popular assumption, even though it might not be correct, Handelsman added.
But one doctor not involved with the study questioned the finding, noting that other lifestyle factors might be affecting testosterone levels as men age. And the study wasn’t designed to take those factors into account.
In the study, the researchers evaluated more than 1,700 men, age 70 and above, in Sydney. The researchers tested the men at the study’s start and then again two years later, when the number of men in the study had dropped to about 1,300.
At both visits, the men answered questions about sexual functioning, including how often they were able to get and keep a viable erection, how often they had sexual activity that led to ejaculation, including masturbation and intercourse, and how much desire for sex they had compared to when they were 50.
The researchers also measured blood levels of testosterone and other hormones at both visits. They found that a decline in testosterone, although it was less than a 10 percent drop, was linked to decreased sexual activity and desire, but not to fewer erections.
“The reduction in sexual function was strongly associated with reduction in serum testosterone [levels] in our study,” Handelsman said. However, the decrease was small and other research has shown that it takes a 70 percent or 80 percent drop in testosterone to affect sexual functioning, he added.
“So, the effect of lower testosterone in the study is too small to cause reduced sexual function, and it must be a cause or an effect, so it is mostly likely an effect of less sexual activity,” Handelsman said.