A study of men with borderline testosterone levels found that half of them suffered either depressive symptoms or overt depression.

The cohort included 200 men, aged 20 to 77, who were referred to George Washington University’s Center for Andrology with testosterone levels between 200 and 350 ng/dl (6.9-12 nmol/L). Researchers there collected each man’s demographic information and medical history, noted what medications each man currently used and checked for signs and symptoms of hypogonadism and measured each man’s testosterone levels again.

The researchers, who presented their findings at The Endocrine Society’s Annual Meeting in San Diego, then used medical history, current medication usage and the validated Patient Health Questionnaire 9 (PHQ-9) to assess depression in the study cohort.

Some 56% of the men had received a clinical diagnosis or depression, were taking antidepressants at baseline and/or scored 10 or above of the PHQ-9.

The findings indicate that men with borderline levels of testosterone are significantly more depressed than either the general American population or demographically similar men. An ethnically diverse sample of primary care populations, for example, found that 15% to 22% of all people scored 10 or more on the PHQ-9.

That said, the most important finding might not have been overall levels of depression but, rather, the reluctance of many men to recognize or report the problem. Indeed, the PHQ-9 identified significant depressive symptoms in dozens of men who denied feeling depressed when asked flat out. Fully 7% of all the men in the study scored 10 or more on the test despite telling the researchers they felt okay.

“This study underscores the utility of a validated instrument to screen for depression, especially as some subjects may deny signs and symptoms during the interview,” the study team wrote in its abstract. “Appropriate referrals should be made for formal evaluation and treatment of depression.”

The population of this particular study tended towards problems other than borderline hypogonadism: 40% were obese while another 39% were overweight. Most patients suffered from erectile dysfunction (78%), low libido (69%) and low energy (52%). Another 42% of them said they suffered from sleep disturbances.

Lack of exercise could have accounted for some of the problem. More than half of all patients (51%) reported no regular exercise beyond walking.

The study authors did not take any stand about whether doctors, in assessing men with borderline testosterone levels and finding evidence of depression, should consider it as an extra symptom of hypogonadism and, thus, an extra factor that would count in favor of testosterone replacement therapy.

Previous research into the effects of testosterone replacement therapy on the mood of hypogonadal men has reached different conclusions about its effects. Some studies suggest that extra testosterone can be a relatively powerful mood booster. Others have found no evidence of significant benefit.

Studies have, of course, found significant evidence that testosterone replacement therapy can improve many of the other symptoms that researchers found in the study population, particularly erectile dysfunction and low libido. There is also widespread agreement that testosterone replacement therapy can help men shed excess fat.

The new study provides no new evidence about the effects of testosterone replacement therapy, but its authors believe that it does provide valuable new evidence about the inverse relationship between natural testosterone and depression. Little previous research had looked for a link between borderline testosterone and depression, they wrote, and the strength of the relationship they found suggests that a significant link does exist.