The male condom is one of the oldest methods of contraception and, critical in the 21st century, one of the best methods to prevent the spread of sexually transmitted diseases.

Yet the male condom remains an "underused" device for sexually active Americans over 50.

This significant conclusion is one of many reached in a study released this week in The Journal of Sexual Medicine.

The study is the most important since the original sexual behavior study completed a little more than 60 years ago by Dr. Alfred Kinsey, says Dr. Pepper Schwartz, professor of sociology at the University of Washington. Schwartz, also "ambassador" on sex, love, and relationships for AARP, studied the sexual behaviors of Americans ages 50-plus for the report.

Q. Why is this study on sexual behavior from age 14 to 94 so important?

A. Because it scans a life cycle. We really have not had a study, until now, that didn't leave out at least one generation. And, frankly, there has been way too little attention paid to changes in sexual behavior on both ends—the youngest and the oldest.

But honestly, the majority of older people have only recently stayed sexually active so late in life. Or if they are not active, they are capable of being active.

Q. We know people are living longer. Your study assesses the context and frequency of sexual behaviors, condom use, and sexual pleasure. It does not seem surprising to conclude that, while people are sexually active into their 80s, the older they get, the less likely they are "partnered." What surprises you about the study?

A. The biggest issue is the low rate of condom use.

At least two thirds of the women do not demand protection. That both surprises and disappoints me.

We are talking about people in their 50s and 60s, who should know about disease. We don't see a significant drop-off in activity until the mid-70s among those who are partnered.

Q. Is there more pressure to have sex since the erectile dysfunction medication was introduced?

A. Many national studies of sexual behavior have not surveyed older adults. The study found relationship status can function in nuanced ways for many older men and women as they find themselves in new partnerships after divorce, illness, or death of their previous partner.

Not surprisingly, relationship status is particularly relevant for women who usually have had fewer sexual partners compared to men. For women, older age is related to a decline in sexual behaviors. Single people of both genders report a higher frequency of masturbation.

I think the use of medications for men has made a huge difference. Why don't they have one for women? Well, a lot of people are trying to work on this. Whenever there is a commercial possibility, there is interest, of course.

Meanwhile, I think vibrator use is going up for all age groups and all genders. It is more acceptable. Although it is true fewer older women will use a vibrator. Mainly because they didn't get permission in their youth, I think.

Q. You say older men don't realize condoms are "more comfortable" today? Don't they get the health message about spreading disease?

A. The problem is the 50-plus crowd doesn't have the same messages. Fifty-year-old women meeting 50-year-old men don't realize they should insist on protection.

Everybody should do it to respect the individual.

It is taking a while for the older generation to catch up to the more liberated younger generations.

Q. Women should insist?

A. Yes.