Sorting out the effect of stress on the heart is made complicated by three factors: 1) people mean different things by “stress;” 2) the kind of stress people think causes heart disease may not be the worst kind; 3) until recently, there has been little scientific evidence that stress causes heart disease.
What kind of stress are we talking about?
When people refer to “stress,” they may be talking about two different things: physical stress, or emotional stress. Most of the medical literature on stress and heart disease refers to physical stress. But most people are referring to the emotional variety when they talk about stress.Physical stress. Physical stress – exercise or other forms of physical exertion – places measurable and reproducible demands on the heart. This physical stress is generally acknowledged to be good. In fact, the lack of physical stress (i.e., a sedentary lifestyle) constitutes a major risk factor for coronary artery disease. So this kind of “stress” is usually considered to be good for the heart – as long as the heart is normal.
If there is underlying heart disease, however, too much physical stress can be dangerous. In a person who has coronary artery disease, for instance, exercise can place demands on the heart muscle that the diseased coronary arteries cannot meet, and the heart becomes ischemic (i.e., starved for oxygen.) The ischemic heart muscle can cause either angina (chest pain), or a heart attack (actual death of cardiac muscle).
In summary, physical stress is generally good for you, and is to be encouraged, as long as you have a normal heart. On the other hand, with certain kinds of heart disease, too much or the wrong kind of physical exertion may be harmful.
But either way, physical stress does not cause heart disease.
Emotional stress. Emotional stress is generally the kind of stress people are talking about when they refer to stress causing heart disease. “It’s no wonder she died,” you’ll hear people say, “with all the mess he put her through.” But is it true? Did Ed really kill Elsie with all his gambling and drinking and staying out all hours of the night?
Everyone – even doctors – have the notion that emotional stress, if it is severe enough or chronic enough, is bad for you. Most even believe that this kind of stress can cause heart disease. But scientific evidence that it actually does so has been hard to come by.
Emotional stress and heart disease
There is a fair amount of circumstantial evidence that chronic emotional stress can be associated with heart disease and early death.Several studies have documented that people without spouses die earlier than married people. (While some might claim this constitutes evidence that emotional stress is actually good for you, most authorities agree that having a spouse actually provides a significant degree of emotional support and stability.) Other studies have shown fairly conclusively that people who have had recent major life changes (loss of a spouse or other close relative, loss of a job, moving to a new location) have a higher incidence of death. People who are quick to anger or who display frequent hostility have an increased risk of heart disease.
So emotional stress is bad, right? It didn’t start out bad. Evolutionarily speaking, emotional stress is a protective mechanism. When our ancestors walked over a rise and suddenly saw a saber-tooth tiger 40 yards away, a surge of adrenaline prepared them for either fight or flight as they considered their options.
But in modern times, now that saber-tooth tigers are few and far between, most often neither fight nor flight is the appropriate reaction to a stressful situation. (Neither fleeing from nor punching your annoying boss, for instance, is generally considered proper.) So today, the adrenaline surge that accompanies a stressful situation is not channeled to its rightful conclusion. Instead of being released in a burst of physical exertion, it is internalized into a clenched-teeth smile and a “Sure, Mr. Smithers, I’ll be happy to fly to Toledo tomorrow and see about the Henderson account.”
It appears that the unrequited fight-or-flight reaction, if it occurs often enough and chronically enough, may be harmful.
