Do women stay sexy -- and interested in sex -- as they grow older? For many of us, the assumption is women stop having sex as they age, either because they are not interested or not physically able to. But a new study finds those ideas are generally untrue.

Researchers at the University of Pittsburgh Medical Center recently completed a study of about 350 women, ranging in age from their 40s to mid-60s, and tracked them for several years to see how their sex lives changed.

They asked the women about their sex lives using a standard test called the Female Sexual Function Index. It asked the women how strong their sex drive was, whether they had trouble becoming aroused, or felt pain during intercourse, among other things.

The researchers found that, over eight years, more than 85 per cent of the women remained sexually active.

Interestingly, the study also found that most of the women scored poorly on the Female Sexual Function Index. And yet, most continued to be sexually active.

One of the most important factors that determined whether women stayed sexually active was their perceptions about sex. Those who said at the beginning of the study they felt sex was highly important were about three times as likely to still be sexually active at the end of the study, compared to those who thought sex was either a little or not at all important.

Dr. Marla Shapiro, Canada AM’s medical expert, says it appears that women who have an interest in sexuality in their younger years, that will persist.

“So that tells you that early investment in that intimacy, in that friendship, in that relationship will predict the survival of intimacy as time goes on,” she told Canada AM of the study with which she is familiar, but was not involved in.

Having a lower body mass index was also a key factor linked with maintaining sexual activity. And white women were more likely to still be sexually active, compared to other ethnic groups.

The study authors say they also learned that the Female Sexual Function Index may not be the best tool for assessing sexual health. That’s because the test focuses so specifically on intercourse. The researchers found that, after menopause, many of the women placed a higher priority on other aspects of sexuality, such as kissing, touching and general intimacy.

The test’s focus on intercourse therefore didn’t accurately reflect what constitutes satisfying sex for older women, the study authors found.

The study's full results appear in the journal, JAMA Internal Medicine.