It is well known that stress can cause cardiovascular disease. Scientists have established the precise link between stress and cardiovascular problems: abnormal production of stress hormones and, surprisingly, inflammation in the brain during chronic stress conditions.
Acute and chronic stress
As we have explained in an earlier article, stress can arise and disappear quickly, or can become long-lasting and turn into a condition of chronic stress.
Acute stress may occur when you have to jump away from a fast approaching car. Once the car has passed (without hitting you I hope), your stress will go away fairly quickly. During acute stress, your body will produce the stress hormones adrenaline (epinephrine), noradrenaline (norepinephrine) and cortisol. These hormones will also be produced during chronic stress, and can be found in high concentrations in the blood for a long period of time.
Effects of stress hormones on the heart and blood vessels
The actions of the stress hormones help you to deal with a stressor, the problem that causes stress, like the upcoming car in the example.
The stress hormones increase heart rate and blood pressure by narrowing the arteries. They also liberate glucose from the liver to supply the body with energy. Also, stress hormones accelerate breathing to increase oxygen levels in the blood. The energy- and oxytocin-rich blood is guided to the muscles, so that they can function optimally for the so-called “fight-or-flight” reactions. You would thus be able to attack or to run away from a stressor (like you do with the upcoming car).
Stress hormones can therefore be life-saving chemicals that circulate in your body when needed. Very useful during acute stress.
Chronic stress and cardiovascular disease
When the body experiences stress for a long time, stress has become chronic. This is a condition that can negatively influence health. The stress hormones keep stimulating the cardiovascular system, which can lead to disease of the heart and blood vessels.
As the stress hormones continuously stimulate the heart and blood vessels, heart rate and blood pressure may be elevated for a long time. This can lead to aggravation of atherosclerosis, thrombosis, and even heart attack.
Other consequences of chronic stress on the cardiovascular system include spasms in the heart’s blood vessels and an interruption in electrical pulses. These lead to irregular heart frequency, chest pain or shortness of breath.
Cardiovascular problems are typically found in people with high-stress occupations, such as fire fighting or law enforcement, and in patients with stress-related disorders, such as depression.
Stress causes cardiovascular disease through inflammation
Scientists have recently discovered that stress can cause cardiovascular disease in two ways. The first is the one we talked about above. It involves mostly the sympathetic nervous system that promotes the release of adrenaline (you can read more about the rapid stress response through the sympathetic nervous system here).
The second way is a bit more complicated, and involves a particular structure in the brain: the amygdala. The amygdala is the brain’s center of fear. It also switches the hypothalamus on to elicit stress responses and hence the production of stress hormones. By making scans, researchers have found that the activity of the amygdala at rest (without stress occurring) can predict whether somebody will develop cardiovascular problems following a stressful event. The more active the amygdala is at rest, the more likely it is that cardiovascular disease will develop.
By making additional scans of the aorta, the blood vessel through which the blood leaves the heart and travels to the rest of the body (except the lungs), scientists observed enhanced activity in people that developed cardiovascular disease later. They observed the same for bone marrow, where blood and immune cells are made. Some of the immune cells are white blood cells that produce molecules that provoke inflammation.
There is thus a pathway from the amygdala to the aorta and the bone marrow, ultimately resulting in inflammation.
Activity of the amygdala in the brain (purple dot) has been linked to the production of white blood cells in the bone marrow. These cells produce chemicals that provoke inflammation in the arteries, leading to artherosclerosis, thrombosis, stroke, or heart attack. The sympathetic nervous system also plays a role in this. How the amygdala and inflammation are biologically precisely linked is currently not precisely known.
Activity of the amygdala in the brain (purple dot) has been linked to the production of white blood cells in the bone marrow. These cells produce chemicals that provoke inflammation in the arteries, leading to artherosclerosis, thrombosis, stroke, or heart attack. The sympathetic nervous system also plays a role in this. How the amygdala and inflammation are biologically precisely linked is currently not precisely known.
Why is this pathway so important for the development of cardiovascular disease during prolonged periods of stress? To answer this question, we have to turn to scientific studies on mice. In mice it was found that the white blood cells inducing inflammation migrate to the wall of arteries (including the aorta) during stress. Here they instigate arthersclerotic inflammation, leading to atherosclerosis. Scientists estimate that inflammation of arteries is a more important way that stress causes cardiovascular disease than the prolonged activity of adrenaline, noradrenaline and cortisol.
Unhealthy habits
There is still a third way by which chronic stress can cause cardiovascular problems. This is rather an indirect way, and concerns the adoption of unhealthy habits.
If you are under chronic stress, you may be tempted to smoke more and to eat high-calorie food such as french fries and hamburgers.
Smoking has many negative effects on the cardiovascular system:
- An instant and long-term rise in blood pressure.
- An instant and long-term increase in heart rate.
- Reduction of blood flow from the heart.
- Reduction of the amount of oxygen that reaches the body's tissues.
- Increase of the risk for blood clots.
- Damage of the blood vessels.
- Double the risk of stroke (reduced blood flow to the brain).
Eating a diet high in saturated fats, such as when you consume cheeseburgers and fries frequently, can reduce the ability of the body’s “high-density lipoprotein”, also known as the good cholesterol, to protect against clogged arteries. High HDL levels reduce, whereas low levels increase the risk for heart disease. Therefore eating the wrong fats puts you at higher risk for developing cardiovascular disease.
What to do to prevent cardiovascular disease during chronic stress
If inflammation is the major risk factor for the development of cardiovascular disease during chronic stress, one could look for ways to reduce inflammation to prevent cardiovascular problems from happening. And such in a natural way.
Fortunately, there is something you can do to achieve exactly this. Many scientific studies have shown the benefits of physical exercise on stress. Individuals who regularly exercise have lower activity of the sympathetic nervous system (and therefore less adrenaline and noradrenaline). Also, the activity of the HPA-axis (and therefore cortisol levels in the blood) is significantly lower in trained people.
Importantly, physical exercise lowers the concentration of pro-inflammatory substances in the blood. Exercise increases the resistance to two of those, TNFa and interleukin-6, and therefore protects the cardiovascular system against heart attack and atherosclerosis.
Physical exercise is one of the best ways to make you more resilient to stress. There are many aspects to this, and we will devote an entire article to this soon.
Another thing you can do to lower stress is to gain control over the problem that causes your stress. The greater the amount of control you perceive you have over a situation, the lower the concentrations of stress hormones in your blood will be. Heart rate and blood pressure do not rise as much as when you would have no control over a situation.
In general, your aim should be to become more stress resilient, and take the causes of your chronic stress away, so that the stress will no longer occur. Stress relief and prevention are therefore important topics in our course "Surmounting Stress" and the Stressinsight Community.
