Decreased Sexual Activity and Desire May Lead to Lower Testosterone in Older Men

By Lorraine L. Janeczko

March 19, 2015

NEW YORK (Reuters Health) - In older men, decreased sexual activity and desire may lower serum testosterone, according to new research from Australia.

Declines in sexual activity and desire, but not in erectile function, may be the cause, not the consequence, of the decrease in serum testosterone, but not in dihydrotestosterone (DHT), estradiol (E2), and estrone (E1), study investigators reported here in a poster March 7 at ENDO 2015, the annual meeting of the Endocrine Society, in San Diego, California.

"Our findings give little support to the huge increase in prescribing testosterone for middle-aged and older healthy and eugonadal men to improve sexual function," wrote lead study author Benjumin Hsu, a PhD candidate in the School of Public Health and the Australian and New Zealand Army Corps Research Institute of the University of Sydney in New South Wales.

"Testosterone therapy should be considered as hormonal replacement for men with reproductive system pathology, not as a treatment for men who complain of sexual dysfunction but do not have reproductive system pathology," he added in an email to Reuters Health.

Hsu and colleagues assessed 1,705 men, aged 70 years and older in Sydney, and they analyzed the data from the 1,226 participants who completed the study.

At the test and retest two years later, researchers asked the men identical questions about their sexual functions, including, "How often are you able to get and keep an erection that is firm enough for satisfactory sexual activity?" and "How many times over the last month have you had sexual activity (including intercourse and masturbation) reaching ejaculation?" and "How much desire for sex do you have now, compared with when you were 50?"

Both times, the researchers also measured serum testosterone, DHT, E2, and E1 by liquid chromatography-tandem mass spectrometry, and sex hormone-binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) by immunoassay.

Over two years, baseline serum testosterone, DHT, E2, and E1 did not predict decline in sexual activity, sexual desire, and erectile function. By contrast, the decline in testosterone (not in DHT, E2 or E1) was strongly associated with decreased sexual activity and desire, but not with erectile dysfunction.

For each standard deviation decrease in testosterone from baseline to follow-up, the adjusted odds ratio for further decline in sexual activity was 1.23 for testosterone.

Men whose ejaculation frequency declined had decreased serum testosterone, and those who became sexually inactive during the two years had a 7% decline in circulating testosterone levels.

Changes in testosterone over 2 years were significantly associated with changes in sexual desire. For each standard deviation decline in testosterone levels, there was an adjusted odds ratio of 1.19 for decline in sexual desire.

For men whose sexual desire declined over the two years, circulating testosterone levels decreased nearly 10%.

Baseline E1 was the only hormone significantly associated with erectile dysfunction, with a multivariate-adjusted OR of 1.19 for each standard deviation decline in E1.

Hsu said his research team is planning further studies to explore the association between hormone level change and sexual function change over five years.

Dr. Bradley D. Anawalt, professor and vice chair of the Department of Medicine of the University of Washington in Seattle, who was not involved in the study, wrote in an email to Reuters Health that "the premise and conclusion are interesting and surprising, but they are not supported by the study findings. Data from other studies suggest that 1) exercise acutely increases testosterone concentrations; and 2) in obese men with low testosterone concentrations, weight loss achieved by diet and exercise may increase serum testosterone concentration."

"The problem is that this is not an intervention," he wrote. "The authors simply measured blood testosterone concentration serially over time and surveyed these men with a questionnaire about sexual activity. It is not a surprise that blood concentrations declined over time; that finding has been confirmed in numerous studies of older men. It is not a surprise that sexual activity and desire declined over time."

"However, the study is not designed to attribute cause and effect," he added.

"For men interested in maintaining normal sexual activity and normal serum testosterone concentrations as they age, the best recipe is regular, ideally daily, exercise of at least 20 minutes (and ideally 40 to 60 minutes), a good, healthy diet of whole grains, fresh vegetables and fruits and avoiding excessive alcohol and any tobacco," he wrote.

The authors and Dr. Anawalt did not report any conflicts of interest.


ENDO 2015.


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