Sexual Research

In the world of sexual research, some experts like to compare men to a light switch: It doesn't take a whole lot of effort to turn them on. Women, by contrast, supposedly have as many gears and dials as the control panel of an airplane, all needing to be synchronized before liftoff.

The analogy may seem pretty simplistic, and even insulting to men. But some researchers say the complexity of women does explain one thing: why there isn't a female equivalent of Viagra -- an all-purpose, sexual-dysfunction-buster. "It's more complex," said Lori Futterman, a specialist in female sexual dysfunction. "Rather than just giving a Viagra, which increases blood flow, we're talking about balancing the whole system."

Women's sexuality has been in the news this month since a Food and Drug Administration panel rejected Procter & Gamble's bid to market the first prescription drug for female sexual dysfunction. Other companies, sensing a possible multibillion-dollar market, are working on similar drugs.

Overall, an estimated 40 percent of women suffer from sexual dysfunction. The wide majority of them -- 85 percent -- have trouble developing desire for sex in the first place. About 10 percent can't get turned on, and an estimated 5 percent can't have orgasms, said Futterman, an assistant professor of psychiatry at the University of California at San Diego.

According to researchers and sex counselors, treatment is challenging because much of women's sexuality takes place above the neck instead of below the waist. "They need to have some type of emotion, some type of caring shown to them," said Rutgers University professor emeritus Beverly Whipple, a neurophysiologist who named and popularized the G spot. "They don't just have a spot rubbed and have an orgasm."

Then again, experts used to think that men's sexual problems were mental: They blamed almost all cases of impotence on psychological factors instead of problems with the male plumbing system. But along came Viagra and its imitators, and millions of men suddenly began having erections again without needing to visit a shrink.

Researchers don't expect a similar turnaround for women, even though Viagra does seem to help some female patients, especially those who are on antidepressants that dampen sexual response. Viagra boosts erections by allowing more blood flow to the penis; circulation problems contribute to women's conditions, too, but at a much smaller level, perhaps affecting just one in 20 women with problems, said Dr. Kate O'Hanlan, a gynecologic cancer surgeon in Northern California.

"Women don't get hardening of the arteries like men do, and women don't have difficulty with orgasms for the same reasons men do," O'Hanlan said. "That's why there's a pill for men."