Testosterone Levels May Be Lower in Men Who Develop Alzheimer's
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By VRP Staff
Two studies published in the January 27 edition of Neurology indicate that free testosterone levels—testosterone not bound to any other substance in the blood—are lower in men who later develop Alzheimers disease and that testosterone levels are controlled by a substance known as sex hormone-binding globulin in both males and females.
Past studies have explored the relationship between Alzheimers and low testosterone levels. Those studies have reported on reduced testosterone levels in men with Alzheimers compared to men who do not suffer from this disease. However, those studies have not determined whether the low testosterone levels are actually a cause of Alzheimers or merely a consequence of the disease itself.
In the two current studies in Neurology, researchers sought to further explore whether low testosterone levels are actually a cause of Alzheimers disease. In one study, they examined data from 574 men who were free of Alzheimers at the studys start and who participated in the Baltimore Longitudinal Study of Aging. The subjects ranged from 32 to 87 years of age at the beginning of the study. In the average follow-up period of 19.1 years, 54 subjects were diagnosed with Alzheimers.
The researchers in this study looked at whats known as the free testosterone index (FTI), which is calculated by dividing serum testosterone by sex hormone-binding globulin. The study authors determined that the higher the FTI, the lower the risk of developing Alzheimers. With each 10-unit increase in FTI, there was a 26 percent reduction in Alzheimers risk, indicating that testosterone does protect against the development of Alzheimers and that low testosterone levels are not merely a consequence of Alzheimers but rather a cause of the disease.
In the other study, Italian researchers examined 32 men and 64 women who already had Alzheimers and compared these subjects testosterone levels with those in 32 men and 72 women free of Alzheimers. In subjects with Alzheimers, levels of sex hormone-binding globulin were significantly higher and the FTI was significantly lower in subjects with Alzheimers. These high levels of sex hormone-binding globulin indicate that testosterone in these patients is not as bioavailable as in subjects who do not have Alzheimers and who have lower levels of sex hormone-binding globulin.
The study authors recommend that further small-scale clinical trials be conducted in groups of men who have low testosterone levels, to determine the effectiveness and safety of testosterone supplementation.
Reference:
Moffat SD, Zonderman AB, Metter EJ, Kawas C, Blackman MR, Harman SM, Resnick SM. Free testosterone and risk for Alzheimer disease in older men. Neurology. 2004 Jan 27; 62(2): 188-93.
Paoletti AM, Congia S, Lello S, Tedde D, Orru M, Pistis M, Pilloni M, Zedda P, Loddo A, Melis GB. Low androgenization index in elderly women and elderly men with Alzheimers disease. Neurology. 2004 Jan 27; 62(2): 301-3.
AndroSpray™ and AndroCaps (available from VRP) contain the testosterone precursors androstenediol and androstenedione.
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