By Matt Brignall, ND

Healthnotes Newswire — Six weeks of weekly intramuscular injections of testosterone led to improvements in some measures of mental function in men over age 50, according to a double-blind trial published in the July 10^th issue of Neurology.¹

In this study, the testosterone injections were associated with improved verbal memory as well as improvement in a test that assessed spatial relations. The authors did not report whether treatment with testosterone was associated with any side effects.

Previous studies of testosterone in older men have yielded mixed results, with some studies showing a benefit and others showing no improvement.^{2 3} However, the specific improvements found in the new study did not come as a surprise, as previous studies have shown that low testosterone levels correlate with declines in spatial and verbal memory.^{4 5}

While testosterone administration appeared to improve mental function over six weeks, long-term studies will be required to analyze the safety of this treatment. There is some concern that treatment with excessive amounts of testosterone could increase the risk of prostate cancer. Testosterone therapy must be monitored by a physician because it has occasionally caused dangerous elevations in blood count, or other side effects.

References
1. Cherrier MM, Asthana S, Plymate S, et al. Testosterone supplementation improves spatial and verbal memory in healthy older men. Neurology 2001;57:80–88.
2. Janowsky JS, Chavez B, Orwoll E. Sex steroids modify working memory. J Cogn Neurosci 2000;12:407–14.
3. Sih R, Morley JE, Kaiser FE, et al. Testosterone replacement in older hypogonadal men: a 12 month randomized controlled trial. J Clin Endocrinol Metab 1997;82:1661–7.
4. Flood JF, Farr SA, Kaiser FE, et al. Age-related decrease of plasma testosterone in SAMP8 mice: replacement improves age-related impairment of learning and memory. Physiol Behav 1995;57:669–73.
5. Morely JE, Kaiser F, Raum WJ, et al. Potentially predictive and manipulable blood serum correlates of aging in the healthy human male: progressive decreases in bioavailable testosterone, dehydroepiandrosterone sulfate, and the ratio of insulin-like growth factor to growth hormone. Proc Natl Acad Sci 1997;94:7537–42.

Matt Brignall, ND, is in practice at the Seattle Cancer Treatment and Wellness Center and at the Evergreen Integrative Medicine Clinic in Kirkland, WA. He specializes in integrative treatment of cancer.

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