When we think about the powers of testosterone, we usually do not consider mental processes. However, research suggests that testosterone levels may affect men’s cognitive performance, reports the January 2008 issue of Harvard Men’s Health Watch.

All the body’s attributes change with age, and mental functions are no exception. Memory is the most fragile mental function. With age, new learning is slower, new information is processed less carefully, and details often slip. These changes give rise to the “senior moment” in healthy elders and to cognitive impairment and dementia in others.

Testosterone levels decline with age, just when memory begins to slow. Might falling hormone levels account for some of the problem? Perhaps, says Harvard Men’s Health Watch. The data are far from conclusive, but studies have found some connections. For instance, higher testosterone levels in midlife have been linked to better preservation of tissue in some parts of the brain. And in older men, higher testosterone levels have been associated with better performance on cognitive tests.

If higher testosterone levels are associated with better mental function, do treatments that reduce testosterone lead to cognitive decline? Three studies linked impaired performance on cognitive tests with androgen deprivation therapy, which is sometimes used in treating prostate cancer. However, the effects were modest and certainly should not deter men from receiving this treatment if needed.

This research also raises the question of whether testosterone therapy might improve mental function in healthy older men, or even in those with cognitive impairment. Only a few small, short-term studies have examined this, and some have reported subtle improvements on cognitive tests. However, high testosterone levels may have harmful effects as well. Harvard Men’s Health Watch suggests that until more research findings are available, men should not use testosterone or any other androgen to improve mental function.