Alberta Cancer Foundation

The Science of Stress

Illustration by Pete Ryan

When Dr. Kathy Hegadoren was diagnosed with breast cancer on May 14, 2010, the nurse who researches stress at the University of Alberta was well aware of what was going on in her body, and in her mind.

“I felt blind-sided,” says Hegadoren, who holds a Canada research chair in stress-related disorders in women. “Even though I didn’t perceive myself as stressed, when I was diagnosed I had lots of behavioural evidence of stress – a hard time sleeping, a hard time concentrating at work – but I didn’t feel jittery. My mind would just wander.”

When she started her first round of cancer treatment in late July, Hegadoren just wanted to get on with it, so she could take some action over her diagnosis. “In some ways, it allows me to feel more in control, which makes you feel less stressed,” she says. “It’s about personal control. It’s a journey. You have to believe in getting up and having hope, not having your diagnosis becoming your whole life.”

A cancer diagnosis obviously causes a lot of stress, but Hegadoren says the concept of stress is very elusive for many people. “It’s so difficult to define because it has so many meanings,” says Hegadoren. “It can be used as a noun, a descriptor, a perception, a physiological and biological pathway, all of those things can be characterized as part of the stress response.”

You can’t see it, but people respond differently to stress in various circumstances and different levels of stress can be either positive, or negative. Too little stress, or too much, has been linked to the onset or worsening of certain diseases, such as heart disease, diabetes and many others.

One of two key stress hormones, cortisol, increases insulin resistance, for example, which means insulin has a harder time getting into certain cells in the body. “If you have that chronic insulin resistance, there is some evidence that chronic state of insulin resistance can increase your risk for Type 2 diabetes,” says Hegadoren.

People who have chronic stress also tend to end up with more symptoms of irritable bowel syndrome and inflammatory bowel disease, according to Dr. Donna-Marie McCafferty, an associate professor at the University of Calgary. She studies the link between irritable bowel disease and cancer, involving metabolic stress. Current research suggests a link between stress and worsening irritable bowel disease symptoms, including diarrhea, stomach cramps and other digestive problems.

Some studies also link irritable bowel disease to an increased cancer risk. “However, no conclusive study demonstrates that stress management has a beneficial effect on inflammatory bowel disease,” says McCafferty. “There are a couple of (studies) which indicate that the duration and severity of inflammation in irritable bowel disease patients is linked to the development of cancer. Therefore, if stress is linked… to irritable bowel disease then, in theory, it could contribute to cancer development.”

Stress even has implications on memory. Dr. Ken Lukowiak, a University of Calgary professor who studies how stress alters memory function, agrees there is a strong link between feeling in control and how stress affects people. “What form the most stressful stimuli are those that we don’t control,” he says. “If you can’t control the stimulus, then you can predict quite highly that it’s going to be a stress stimulus in the wrong way. Some stresses are very useful and others are extremely detrimental.”

Yet, even Hans Selye, a Hungarian-born Canadian who Lukowiak calls the “father of stress research,” had a famous quote about how elusive stress is for most people, saying: “Everybody knows what stress is, but nobody really knows.”

Lukowiak describes stress as a bell-shaped curve, where you plot memory function, from poor to good, on one axis and stress level on the other axis. “At low stress, you won’t learn anything and if you are far too stressed out, you’re not going to learn anything,” says Lukowiak. “There’s an optimal level of stress that one wants to achieve. You want to always get into that sweet spot and that sweet spot is going to change dramatically, depending upon all sorts of things.”

Age and individual circumstance, for example, can greatly alter what would be considered the optimal, moderate level of stress. “It’s all in the eyes of the beholder and, even then, it’s going to change depending on your internal state,” he says.

Kathy Hegadoren knows that her mental state changed when she learned of her breast cancer diagnosis, but she credits a strong support network, personal resources and a positive outlook with helping her to achieve a balanced state, despite the presence of some understandable stress. “Stress is actually very positive and, in its most elemental way, it’s our instinct to survive,” says Hegadoren. “When we talk about disease, not only can overwhelming stress lead to chronic diseases, but it can lead to mental disorders.”

Being aware of stressors in your life is the first important step to address how you handle your body’s response and how you cope mentally. Hegadoren, meanwhile, is focused on her treatment plan and will continue her own journey, dealing with stress the best she can along the way. “I have a huge support network – a strong marriage, children who care deeply about me and lots of people that love me,” she says. “I have the luxury of having lots of things that others don’t always have.”