The stress of aging

By James Martin

Interview with Jens Pruessner, director of the McGill Centre for Studies in Aging

Jens Pruessner studies the psychoneuroendocrinology of aging. Much of his research focuses on biomarkers— such as the hormone cortisol, heart rate and blood pressure—to assess your levels of stress and their relationship to neurodegeneration. “The long-term goal,” he says, “is to hopefully understand the mechanisms behind neurodegeneration and prevent it from happening.” The last five years have seen his work — and, indeed, much of that done at the McGill Centre for Studies in Aging (MCSA) at the Douglas Mental Health University Institute, where he’s served as director for the past two years — switch from finding a cure to such preventative interventions. “We’ve realized that efforts to intervene once someone has a disease such as Alzheimer’s have not been very successful,” he says. “The changes in the brain have been so great that all we can do is maybe slow the progression, but we can’t stop it. If we can start the process earlier, we have a chance to prevent full-blown onset — and to do that, we need reliable biomarkers and better methods to detect who is normally aging and who is moving toward disease.”

Photo by Allen McInnis
How does stress affect aging?

If you’ve been chronically exposed to high levels of stress over the course of your life, there’s a chance that this has chronic effects on your cortisol regulation—which greatly increases your chances of developing a host of health problems. Our work investigates the link to develop dementia and neurodegeneration as a consequence of life-long stress, and how it affects our brain. We are still only beginning to understand that link, and all the factors which are involved, but it seems that there is a systematic relationship that warrants further investigation.

How do you define stress in your studies?

We use the definition by Richard Lazarus which involves comparing your available resources with the demand of the situation at hand. If you feel you’ve got what it takes to cope with a certain situation—whether it’s the daily hassle of getting your children to school on time, or a major occurrence like losing a loved one—you’re not stressed. You may be challenged, but you can do it. We’re studying the stress response that happens when you feel that you don’t have what it takes.

Is that response the same for all types of stressful situations?

No, there are two stress systems. Fight-or-flight is the stress of facing a wild lion. The other one, the hypothalamic pituitary adrenal axis, is more about responding to social situations — the end product of that axis is the hormone cortisol, and that’s what we’re studying. It’s particularly important for aging research as it has been shown to have neurotoxic properties, which might influence how our brain ages.

What is social stress?

A big part of it now is insecurity about losing status or rank as a consequence of a negative outcome. The psychological term is “social evaluative threat.” If you failed to complete an assignment at work, for example, you could lose the respect of your co-workers when they realize you’re not on the top of your game. It’s a very powerful source of stress for your hormonal system.

Why the focus on social stress? Is it just because it’s more predominant, or does it have more effect on the aging process?

Social stress is the worst stress to have. Fight-or-flight seems to be more transient: Adrenaline levels skyrocket but go back to baseline very fast. Social stress is longer lasting; we’re observing cortisol changes that last for hours, which puts your whole system in a state of extreme defensiveness and the consequences last longer before you return to the baseline.

Jens Pruessner’s research is funded by the Canadian Institutes of Health Research, the Natural Sciences and Engineering Research Council of Canada, the Alzheimer Society of Canada, Fonds de recherche en santé du Québec and the donors of the McGill Centre for Studies in Aging.