A prospective population-based study has found that higher estrogen levels in older men are associated with an increased risk of dementia. By contrast, levels of testosterone were not associated with cognitive decline. The study is in the August issue of Annals of Neurology, a journal published by John Wiley & Sons. (http://www.interscience.wiley.com/journal/ana).
As our population ages, the impact of dementia will grow. By the year 2050, some 13 million Americans could have Alzheimer's disease, which is the most common cause of dementia. Researchers are searching to understand risk factors and some studies have suggested that sex hormones play a role. One large study showed that women receiving estrogen therapy had an increased risk of cognitive impairment and dementia. However, the evidence for how testosterone levels affect men is contradictory.
To better understand the role of sex hormones in dementia, researchers led by Mirjam Geerlings, Ph.D. of the University Medical Center Utrecht, studied whether older men's levels of testosterone and estrogen were associated with their risk of cognitive decline and developing dementia, including Alzheimer's disease.
They examined data from the prospectively studied population-based cohort of 2974 Japanese-American men aged 70 to 91 who participated in the Honolulu-Asia Aging Study. Participants showed no signs of dementia at baseline in 1991-1993, at which time fasting blood samples were drawn. The researchers measured the levels of testosterone and estradiol, the major estrogen in humans, in the samples and the men were reexamined for evidence of cognitive decline or dementia in 1994-1996 and 1997-1999 using the Cognitive Abilities Screening Instrument (CASI). At each exam, researchers also collected physical, demographic and medical information.