Public Release: 

Testosterone May Affect Learning Skills; May Be Put In Tablet Form

Johns Hopkins Medicine

Johns Hopkins scientists studying testosterone-replacement therapy report that the primary male sex hormone may affect some learning skills, including improving visual and perceptual abilities. The findings may provide additional insight into testosterone's role in the brain.

"This is an interesting, early finding and it highlights the importance of studying the effects of sex hormones on brain function," says Adrian Dobs, M.D., senior author and an associate professor of medicine.

Results of the study, funded by the National Institutes of Health, will be presented June 14 at the International Congress of Endocrinology's annual meeting in San Francisco. Ten men with low testosterone underwent word, memory, coordination and other learning tests while on and off testosterone treatment. When receiving testosterone, they had improved visual and spatial skills and a better "mental grasp of objects" -- fitting building blocks into the correct spaces, identifying pictures and remembering shapes, patterns and locations, the results showed. When not receiving testosterone, the men showed improved verbal fluency and verbal memory -- making up sentences, defining words and recalling words from a test.

Researchers at Hopkins and elsewhere are studying whether testosterone-replacement therapy may improve men's muscle mass and strength, bone density, cholesterol level, sense of well-being, cognitive function and balance.

"Compared to estrogen research, we're 15 years behind in investigating the benefits of testosterone," says Dobs.

Testosterone replacement therapy has been shown to improve sexual function in men with low testosterone, while many studies suggest that estrogen replacement therapy reduces the risk of heart disease and osteoporosis in women after menopause. It is unclear whether estrogen replacement therapy increases the risk of breast cancer. Hopkins scientists also are investigating whether estrogen has a role in brain function, including preventing or delaying the onset of Alzheimer's disease.

Other authors of the current study were J.B. Rich, M.D., of York University in Ontario, and Jason Brandt, Ph.D., of Hopkins.

A new form of testosterone delivered in a tablet may improve sexual function in men with low testosterone without side effects, a Johns Hopkins study shows.

"This is an easy way to administer a drug, and it was found to be safe and effective," says Dobs, the lead author.

Results of the study, funded by the National Institutes of Health and Watson Pharmaceuticals, will be presented June 12 at the International Congress of Endocrinology's annual meeting in San Francisco.

Thirteen men with low testosterone received a testosterone tablet that dissolves in the mouth or a placebo. Three months later, the men receiving the hormone tablets had normal sexual function and performed significantly better than those getting the placebo, the results showed. The tablets allowed the men to perform as well sexually as when they received testosterone injections but without prolonged exposure to a high hormone level caused by injections. The hormone level rises and drops steeply with injections, often causing mood swings and other side effects in some men. Studies have shown that recently developed testosterone skin patches also deliver the hormone at a steady level for a long period.

Other authors were Kathy Lesh, R.N., Donald R. Hoover, Ph.D., and Richard P. Allen, Ph.D.

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