The struggles of a lifetime together may well take a toll on a couples' passion for each other.

But not on love. There's no age limit on love.

Psychologist Norm O'Rourke says love may help sustain people in their later years.

His research has shown people who idealize their partners later in life, who unconsciously choose to remember only the good things, have fewer incidents of chronic disease.

O'Rourke, an assistant professor with the department of gerontology at Simon Fraser University in Burnaby, B.C., is now recruiting couples who he will follow over three years to try to find out why.

"In the lab, we're looking at physiological processes that might be related to this idealization process, which seems to be related to superior physical health outcomes.

"Why are people who idealize a spouse more likely to have fewer chronic health conditions?"

He is focusing on the partner in the relationship who idealizes the most. O'Rourke says their view of the relationship has no effect on how the other person sees it. They may or may not idealize. If they do, it could be to a lesser degree.

To find out more, he is working with couples to find a common point of disagreement. Financial issues are most common and then there's sex, inlaws and children.

"Basically, we're asking them to have an argument," says O'Rourke, who has funding for his research on love from the Canadian Institutes of Health Research.

His lab has been set up to resemble a comfortable living room in which couples are asked to discuss various ways they might resolve their issues.

He tapes the conversations and studies facial expressions and body language in addition to what the couples say to each other.

O'Rourke also takes samples of the hormone cortisol before, during and after the discussion to measure stress levels.

If cortisol levels spike over the course of the discussion and remain high, then he knows that stress levels have increased significantly.

From early results, O'Rourke has noticed where one or both partners idealize their married lives, they don't fight as much as they discuss.

"They approach the talk as an opportunity for growth, to learn something new. They listen and remain calm and rational. They approach it as more of a challenge than fight," he says.

O'Rourke assumes that within these couples, cortisol levels remain relatively low -- and so does the stress.

This is an important finding, because high cortisol levels are significantly associated with illnesses such as heart disease.

O'Rourke says whether people will end up idealizing their spouse in old age depends on their personality factors.

"The most important one seems to be the absence of a trait called neuroticism or a tendency toward negative emotional responding," he says.

"People who are higher in the trait of neuroticism tend to be more on edge, more prone to depression."

O'Rourke says people who aren't neurotic are more easy going, and more likely to idealize their spouse and approach arguments in a calm, open way.

"You know, those people who can withstand travails of life without too much hardship," the psychologist says.

To learn more about the phenomenon of marital aggrandizement, as O'Rourke likes to call this process of idealizing one's spouse, he intends to follow couples over time.

O'Rourke will watch how their health changes and what factors predict these changes.