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Low Testosterone Linked to Alzheimer’s Risk

Study Shows Low Levels of the Male Sex Hormone May Be a Predictor of Cognitive Decline
WebMD Health News
Reviewed by Laura J. Martin, MD

Oct. 8, 2010 -- Low testosterone levels in older men with memory problems may signal progression to Alzheimer’s disease or even increase the risk for developing age-related dementia.

In a newly published study, older Chinese men with early memory declines who did not yet have Alzheimer’s were far more likely to develop the disease over a year of follow-up if they had low testosterone at enrollment.

The study was small, but the findings suggest low testosterone may be an independent predictor of rapid cognitive decline in older men with early memory loss, Saint Louis University Medical Center professor of gerontology John Morley, MD, tells WebMD.

“The next step would be to replace testosterone in these men with memory declines to see if we could slow the progression to Alzheimer’s disease,” Morley says.

The Testosterone-Alzheimer’s Link

The study, led by researchers at the University of Hong Kong, included 153 older Chinese men followed for one year.

All the men underwent testing to assess memory function at enrollment, and 47 were determined to have evidence of mild cognitive impairment.

Over the course of the next year, 10 men received a diagnosis of Alzheimer’s disease. All were in the previously identified group with early memory declines and all had low levels of free testosterone in blood samples.

Free testosterone level was one of only three independent predictors of progression to Alzheimer’s disease in the study. The others were high systolic blood pressure and presence of the apolipoprotein E (ApoE) protein genotype, which is an established genetic risk factor for Alzheimer’s disease.

According to the National Institute on Aging, the genetic variation occurs in about 25% of the population and about 40% of people who develop Alzheimer’s disease late in life.

Men in the study with the genotype were five times as likely to develop Alzheimer’s disease over the next year as men without it.

The research appears in the online version of the Journal of Alzheimer’s Disease.

Testosterone’s Role in Preventing Alzheimer’s

The study is not the first to suggest a protective role for testosterone in Alzheimer’s disease.

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