In an uncomfortable reversal of roles, new research suggests the children of baby boomers may have to sit down to have "the talk" with their aging parents.

Sexually transmitted infection rates have doubled in the past decade among adults aged 50 to 90 in Canada, the U.S. and the U.K., says a study released Thursday.

There has also been a significant increase in the number of older adults accessing HIV care, up 82 per cent since 2001. While much of that increase is due to HIV patients living longer because of new treatments, new HIV diagnoses in adults over 50 doubled between 2000 and 2009 in the U.K.

The statistics also show increases in incidents of syphilis, chlamydia and gonorrhoea in adults in the 45-to-64 age bracket.

"Over the last 10 to 15 years, we were seeing in this (over 50) group that . . . (sexually transmitted) infections were really rising . . . across the board," one of the study's authors, Rachel von Simson, told CTV News. "In some cases, they now form a larger group of infections than those aged 15 to 29.

"Statistics show in Canada that in adults over the age of 45, they are seeing more cases of syphilis in them than in adults aged 15 to 29."

The authors of the study, von Simson, a medical student at King's College London and Ranjababu Kulasegaram, a doctor specializing in genito-urinary medicine at St Thomas' Hospital London, say little research has been done on why there has been the rise of STIs among older adults.

The authors' say post-menopausal women are physically more vulnerable to STIs, which is a factor.

"Post-menopausal changes to the vagina, such as . . . narrowing and shortening of the vagina, and decreased lubrication leave women more vulnerable to minor genital injuries and microabrasions that facilitate the entry of pathogens," the report says.

But the authors note that physical changes do not explain why older adults are exposing themselves to more sexual risk.

They theorize that the increase in the use of erectile dysfunction drugs has allowed men to stay sexually active longer, increasing the amount of time a man can put himself and his partners at risk.

"When we started seeing Viagra used more in the late 1990s, that was really the start of this upswing," von Simson said.

A recent study out of the U.K. said 80 per cent of adults over 50 there are sexually active.

Family doctors and other physicians, especially those prescribing erectile dysfunction drugs, should discuss safer sex methods with their older adult patients, the authors say.

Von Simson says doctors should look at older patients the same way they do younger patients, and examine the possibility that they may have an STI.

"Doctors don't really particularly expect to see (older) patients at risk, so they might not be picking up infections like HIV early on when they need treating and that might mean a greater spread," von Simson said. "(Doctors) are very afraid they may offend older adults by speaking about it."

The study is published in the Student BMJ, the international medical journal for students.

With a report from CTV's medical specialist Avis Favaro and producer Elizabeth St. Philip