Myocardial infarctions are the leading cause of death worldwide. It is a type of lifestyle-related coronary heart attack; in particular, the occurrence of heart attacks is directly influenced by sustained stress and unhealthy habits.
In this article we will analyze the mechanisms by which stress can facilitate the occurrence of heart attacks . In order to do so, we must first define these two concepts.
What is stress?
We can define stress as a set of physiological responses to the appearance of stimuli or situations that the organism perceives as threatening or demanding .
These reactions of the body are unspecific and stereotyped; this means that they do not depend on a particular type of environmental stimulation and that they are very similar regardless of the causes that provoke them.
The physiological stress responses depend on the activation of the hypothalamus-hypophysis-adrenal axis and the autonomic nervous system . Short-term effects consist of an increase in heart rate and consumption of stored energy, as well as other signs of physical activation.
Physiologist Hans Selye described three phases of stress in his model of the General Adaptation Syndrome. During the alarm phase the body recognizes the stress and moves to cope with it; if the stress still persists, it moves into the resistance phase, where the activation decreases somewhat in order to be maintained in the long term.
When the organism has consumed its resources the third phase appears, called “exhaustion” and characterized by the reappearance of the intense symptoms typical of the alarm phase. Although the advanced phases of the stress response harm the organism, the alterations usually disappear after a period of rest during which the person generates new energy reserves.
Consequences of Stress
When stress is sustained, it causes what is known as stress syndrome, consisting of the appearance of peptic ulcer, the increase in the size of the adrenal gland and the decrease in the thymus. These alterations are related to the massive secretion of glucocorticoids and the suppression of the immune response , which facilitates the development of disease.
Today’s increasingly stressful lifestyle has promoted a clear increase in the prevalence of blood circulation disorders, such as heart attacks and hypertension. Having high blood pressure increases the likelihood of atherosclerotic plaques, and therefore of cardiovascular accidents.
There are also many psychological symptoms that can be influenced by stress: anxiety, irritability, apathy, sadness, emotional instability. Among the disorders caused by stress , anxiety and depression stand out, which, like cardiovascular disorders, are considered lifestyle diseases.
Definition of heart attack
Heart attacks are the world’s leading cause of death, according to the World Health Organization, and their frequency is increasing; while in 1990 they accounted for 12% of deaths, in 2013 this figure was close to 17%.
A heart attack is the death (or necrosis) of part of the tissue of an organ. Necrosis usually occurs as a consequence of the obstruction of the artery that irrigates it .
When necrotic tissue is found in the heart muscle we speak of myocardial infarction. Heart attacks can also occur in other organs; besides the heart, the most common ones are the brain, the kidneys and the intestine.
If the accident takes place in the kidneys we speak of renal infarction, while if it takes place in the intestine the correct term is “mesenteric intestinal infarction”. Strokes are known as “cerebrovascular accidents” or “encephalic vascular accidents”.
Arterial occlusion is usually due to the accumulation of atheroma plaques (or atherosclerosis) but can also be the result of hernias, the presence of tumours or deformation of the organ.
Among the most relevant factors that predispose to the appearance of heart attacks are the consumption of tobacco and alcohol, obesity, sedentary life , diabetes and high cholesterol levels. They also occur more frequently in men, in people over 40 years old, and in those with a family history of cardiovascular disorder.
How does stress cause heart attacks?
The appearance of heart attacks as a result of stress is due to the conjunction of a series of interrelated causal mechanisms. In particular, scientific research has linked heart attacks to increased levels of cortisol and hyperreactivity of the amygdala.
Cortisol is a steroid hormone that is produced in the adrenal gland and is released in response to conditions of stress. Although it is essential for the body to be able to consume energy, continued excessive secretion of cortisol can inflame the arteries, narrowing them and making it easier for them to become blocked.
The tonsils are two brain structures that are located in the temporal lobes and are involved in the learning of emotional responses , including those of fear, anxiety and stress. When stress levels are high for much of the time, neurons of the amygdala learn by classical conditioning to provoke stress responses to stimuli that do not really pose a threat.
Therefore, continuous stress in itself negatively affects the cardiovascular system, but also makes it easier for the amygdala to associate the fear response with harmless stimuli . This produces a vicious circle in which stress causes more stress, increasing the risk of heart attacks and other circulatory problems.
However, the continued practice of physical and cognitive relaxation exercises can help the body stop giving off stress responses at inappropriate times. Scientific research supports particularly progressive muscle relaxation procedures and slow, deep breathing.
- Ressler, K. J. (2010). Amygdala Activity, Fear, and Anxiety: Modulation by Stress. Biological Psychiatry, 67(12); 1117 – 1119.
- Tawakol, A. et al. (2017). Relation between resting amygdalar activity and cardiovascular events: a longitudinal and cohort study. The Lancet, 389(10071); 834 – 845.