Slap and tickle in the sixties, seventies and eighties - those oldies are still at it!

According to a new study, for many seniors sex remains an important issue in their lives.

The researchers say seniors into their 80s and 90s put time and effort into their sex lives even when illness or other problems present a problem.

The researchers found that for many older people sex is as regular a part of their lives as it is for younger people.

Lead researcher Dr. Stacy Tessler Lindau of the University of Chicago says the frequency of sexual activity does not change a great deal across age groups.

For their study Lindau's team carried out surveys of more than 3,000 American adults which were designed to give some insight in what is normal and what is possible for senior citizens.

The researchers defined sexual activity as "any mutually voluntary activity with another person that involves sexual contact, whether or not intercourse or orgasm occurs".

The research team found that 73 percent of people aged 57 to 64 reported having sex at least once in the past year, which put them into the "sexually active" category of the study.

The number fell to 53 percent for men 65 to 74 and to 26 percent for those 75 to 85; women were likely to be less active possibly because they were more likely to be without a partner.

Dr. Lindau says around 50 percent of men and a quarter of the women reported that they masturbated, and this was irrespective of whether or not they had a sexual partner and she says this suggests that in older adults there is an internal drive or need for sexual fulfillment.

The researchers say while the prevalence of sexual activity declines with age, a substantial number of men and women engage in vaginal intercourse, oral sex, and masturbation, even in the eighth and ninth decades of life.

Lindau says the discussion of sexuality later in life has long been a taboo subject, and doctors like everybody else have been guilty of perpetuating stereotypes.

She says the study allows people to see where their experiences align against the experience of others of similar age and similar health status and might also encourage doctors to ask more questions about a patient's sex life and arrange for treatment if necessary.

The study revealed that:-

• more than half of the sexually active people surveyed said they had sex with a partner two or three times a month, even at age 75 to 85;

• that 14 percent of men and 1 percent of women said they took some type of drug to improve sexual function;

• that 35 percent of women rated sex as being "not at all important," compared to just 13 percent of men.

About half of those questioned said they had at least one bothersome sexual problem; for men, it was often erection difficulties, lack of interest or climaxing too quickly; while for women, the problems included pain, inability to climax or lack of lubrication.

When men aged 75 to 85 who had a spouse or intimate relationship were asked why they had not had sex in the last three months, 19 percent cited lack of interest, 17 percent said their partner was not interested, 9 percent said religious beliefs prohibited sex outside marriage and 2 percent said they lacked the opportunity.

Sixty one percent cited health problems or limitations, and 23 percent said the limitations of their partner was the reason.

The study reveals that the assumption that people old enough to be grandparents are too old to care about sex, is misguided, as it is clear that sex looms large in the lives of the over-60s.

The study was funded by the National Institute on Ageing, part of the US National Institutes of Health (NIH) and is published in the New England Journal of Medicine.