April 21, 2000 -- A team of British researchers has discovered a possible explanation for why some guys are so successful with pick-up lines: men who have been given high levels of the male hormone testosterone appear to have improved verbal abilities, compared with fellows who have normal levels of the sex hormone.
Although generalizations about gender-related skills are controversial, research suggests that men with normal amounts of testosterone are, as a rule, better than women at tasks requiring visual and spatial abilities, such as assembling blocks according to a specific design. Women are thought to excel at verbal tasks, such as word association.
But as Daryl O' Connor, PhD, and colleagues in Lancashire, England, discovered, healthy young men who got weekly injections of testosterone for two months -- enough to boost their blood levels to twice the normal amount -- showed significant improvement on tests of verbal ability, but seemed to have decreased spatial ability. In other words, the guys with extra testosterone tended to display a more "female" way of thinking.
There were no changes in any other measures of thought processes, and control subjects -- a similar group of men who received harmless dummy injections of a salt solution -- had no significant changes in any measures of mental ability. The research was reported at a recent meeting of the British Psychological Society.
The study suggests that the effects on thinking of extra testosterone may be due to the fact that testosterone can be converted in the body into estradiol, a form of estrogen, or into dihydrotestosterone, the form of testosterone that causes the development of secondary sex characteristics at puberty and governs adult sexual function.
"There is clearly data in animals that suggests that testosterone or its derivatives ... enhance memory," John E. Morley, MD, professor of internal medicine at St. Louis University, tells WebMD. Morley, who was not involved in the current study, has extensively researched hormonal replacement therapy in men.
"It was a surprise to find this elevation in verbal ability compared with the placebo group," O'Connor, a psychologist at the University of Manchester in England, tells WebMD. "It suggests, particularly with the reduced performance in the spatial ability, that there might be an optimal level of either testosterone or estradiol for optimal performance of different tasks."
O'Connor tells WebMD that men with a condition known as hypogonadism, in which their bodies produce abnormally low levels of testosterone, tend to do worse on spatial-ability tests than men with normal testosterone levels. In addition, in studies of female-to-male transsexuals -- women who receive testosterone injections as part of a sex-change program -- the women start out with typical female thought patterns, but after three months of testosterone therapy, they often exhibit enhanced spatial abilities and decreases in verbal skills.
O'Connor and colleagues say that the results of the latest study may contribute to the understanding of hormone-replacement therapy in men and to efforts to develop a male contraceptive. Some contraceptive methods now under study involve weekly or monthly injections of testosterone, which has been shown to suppress sperm production in many men.
The FDA recently approved a testosterone skin patch for treatment of men with hypogonadism. But testosterone supplements are not recommended for men with normal levels of the hormone, since it could increase the risk of enlargement of the prostate gland and encourage the development of prostate cancer. Injections of testosterone and other "anabolic steroids" are sometimes illegally used by athletes to improve muscle mass, but there are significant dangers associated with its use. These include heart disease and the potential for violent behavior.
Morley cautions that the results of the British study could be misleading. "The problem with giving 200 milligrams of testosterone to young men, without carefully looking at their testosterone status to start with, is that in some of them you may actually be producing an increase in testosterone, but in some you may actually be decreasing it a little bit, depending on when you test for it," he tells WebMD.