Among those surveyed for the study, 78 percent of men aged 75 to 85 reported having a spousal or other intimate relationship, while only 40 percent of women reported the same.
While there exists a tendency for the mind to run wild with possible explanations for this discrepancy, the real reason may be much simpler.
Men generally tend to marry younger women, remarry earlier after divorce or death of a spouse, and eventually die younger than their female counterparts.
Also, just as with younger generations, older men and older women may have different reasons for engaging in sexual activity.
In an editorial that accompanies the study, Dr. John Bancroft of the Kinsey Institute for Research in Sex, Gender and Reproduction in Bloomington, Ind., cites relationship and intimacy as one of the major motivations for sex in women.
Sadock agrees. "Being in a caring and intimate relationship is of extreme importance, especially for women," she said.
Women also appear more likely to rate sex as an unimportant part of life, and they were more likely to report that they no longer get pleasure from sex.
Such a situation is a familiar one for 71-year-old divorcee Lynn Kaleen of Spring, Texas.
"My sex drive has diminished over the years, especially after I turned 50," she said. "My libido basically died out. It surprised me."
Physicians also cite physiological reasons for these differences. Menopause plays a role in women's hormonal profile, as well as their own feelings of sexuality. For men, there are changes in certain blood vessels which can cause erectile dysfunction as well as changes in testosterone levels that can affect their sex drives.
Mautz said that when her doctor asked her whether she was seeing anyone, she started to rattle off a list of other physicians with whom she had had recent appointments -- until she realized that her doctor was inquiring about her intimate relationships.
"I am rarely asked about this by other doctors," she said. "It took me by surprise."
She may not be alone. According to the new study, only 38 percent of women and 22 percent of men had discussed sex with their physicians since turning 50.
Butler said he feels the underlying problem is twofold.
"Doctors in general have hardly any time to talk to patients," he said. "They are also not educated about sexuality -- especially old age sexuality."
Lindau adds that there are other issues as well. For example, she said, older women may feel too embarrassed or intimidated to ask a young male doctor about sex.
But as new information about sex in seniors continues to unfold, doctors say that conversations about sex must become more of a fixture in older Americans' doctor visits.
"It should be a routine part of any general clinical appraisal to check whether there are any sexual concerns," Bancroft said. "It is then up to the patient whether he or she responds."