History of Stress

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History of Stress

Discover our podcast on History of Science and on health made by Florian and Yannick.

Hands shaking, sweating, the heart beating fast and strong… Everyone has already experienced these reactions to external aggression. But what do these reactions make you think of? Stress of course! The stress that everyone knows, and that will be our subject this November, is probably as old as mankind. But it was only discovered biologically in the first half of the 20th century. In this episode, we will study the few advances that allowed this biological discovery, starting, just this once, from the nineteenth century. At the end of this episode, we will also talk about Post Traumatic Stress Disorder, which aroused the interest of scientists only recently.

Around the concept

Mankind always tried to understand emotions and Charles Darwin, in particular, also showed a deep interest in them in his book published in 1872, The expression of emotions in humans and animals. In this book, the author of On the Origin of Species focused on six emotional states: happiness, sadness, fear, anger, surprise and disgust. But stress, or its equivalent, was not present in this book. Why? Because stress had not been “discovered” biologically at the time, and its terminology was still far from being established. But while the book of Charles Darwin was published in 1872, it was Claude Bernard, a French physiologist, who, that same year, would lay the foundations of stress research. He published his theory of the Constancy of the Internal Environment where he claimed that the organism is subject to a law of restoration of its internal environment towards a constant equilibrium.

A few decades later, it was an American physiologist, Walter Cannon, who invented the word homeostasis, whose concept was precisely defined by Claude Bernard, and summarized as follows by the Association Meditas Cardio: “An organism solicited by certain external constraints tends to produce adaptive responses. These adaptive responses have a high energy cost and the body must provide enough energy to react and thus ensure the stability of its internal environment.” Those who have been listening to our Podcast for a few months probably have recognized a certain reference to the theory of Humors and its quest for a perfect equilibrium. Cannon would also describe, in 1915, the two answers that, according to him, are possible in front of stress in his famous phrase “Fight or Flight”. A few years later, in 1928, he also emphasized the link between physiology and emotions to respond to stress. Cannon had demonstrated that adrenaline helps to cope with aggression, and all his work on the subject, would have a great influence on a certain Hans Selye.

But before mentioning Selye, it also seems important to mention Sir William Osler, a Canadian cardiologist living in the United States, who linked stress with heart problems. For him, and I quote: “To exercise a profession of high responsibility increases the risk of heart disease.” In fact, Osler noted that a strong stress felt by a patient could have an influence on the trajectory of a disease. What denotes him from his contemporaries is that Osler recognized the role of cognition in health problems.

Hans Selye and the “invention” of stress

But the creator of the biological concept of stress was Prof. Hans Selye, a man born in 1907 in the Austro-Hungarian Empire, in Vienna, and who emigrated to North America in 1931, first to the United States where he studied at the Johns Hopkins University, then to Canada, at the McGill University in Montreal. He later founded and directed the University’s Institute of Experimental Medicine and Surgery and the World Institute for Stress, also in Montreal, a city where he died in 1982 at the age of 75.

On July 4, 1934, Selye, then research assistant, published in the journal Nature “A Syndrome Produced by Diverse Nocuous Agents“, where he developed his idea of the General Adaptation Syndrome (GAS), which can be described in three phases:

The first phase is the alarm reaction, during which the body defends itself. The second phase is the resistance phase, where the body adapts to the aggression, which is still in force, concentrating its reserves against this aggression. The third phase is the exhaustion one, where the body, after this effort of adaptation, finally gives up, even if the aggression is over.

But it was more than twenty years later, in 1956, that Selye would be globally recognized with his book The Stress of Life, where he synthesized his theories around stress and the General Adaptation Syndrome. Polyglot by his origins (his mother spoke German and his father wanted him to learn Hungarian) and his experiences (he studied in Prague and Rome in his youth, and spent the last part of his life in the francophone Canada), Selye did not, however, find a French equivalent to the English word ”stress”. He therefore decided to keep the English word and thus created a new French word.

Our historical proximity to Selye has allowed us to access its many books and testimonials easily, including its biological discovery of stress. In this connection, he stated: “The idea of the concept of stress and the general adaptation syndrome came to me in 1925 when I was studying medicine at the University of Prague. […] I filled myself to the maximum with theoretical knowledge and I burned with enthusiasm for the art of healing […]. What struck me as a novice was that, apparently, very few symptoms characterized each disease; I could not understand why, from the dawn of the history of medicine, doctors had concentrated all their efforts on the recognition of particular diseases and the discovery of specific remedies without lending any intention to something much more obvious: “the syndrome of just being sick.” François-Joachim Beer, in a communication entitled History of the biological concept of stress, which was presented before the French Society of History of Medicine on January 22, 1977, told us: “From his first observations, Selye found the effects of stress, which later taught him that a large number of diseases, whether somatic, sociological or psychological, may be caused not by a toxic agent or a social situation, but by the reaction of the body. ”

In 1974, a few years before his death, Selye also distinguished two forms of stress. The ”distress”, which refers to negative / unpleasant feelings, and the “eustress” which refers to positive feelings, of well-being. In Selye’s terminology, stress-related research in many therapeutic areas is therefore largely focused on distress. Because for him, whether positive or negative, stress is associated with each of the activities of our existence and is therefore “the spice of life“.

Post-traumatic stress disorder

Selye has also developed theories and concepts on the body’s response to emotions, including post-traumatic adaptation. This gives us a great opportunity to discuss the Post-Traumatic Stress Disorder, commonly known as PTSD. The term Post Traumatic Stress Disorder (PTSD) has become widely known since its first appearance in 1980 in the third edition of the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association. At the time, this term was associated with the psychological conditions of many American veterans of the Vietnam War. It is interesting to note that PTSD has had different names for different eras and conflicts. For example, the term “soldier’s heart was used during the Civil War in the United States (1861-1865). That of “Shell Shock” was used during the First World War and was of course referring to the harsh and terrible conditions of trench warfare. Finally, the term “war neurosis” or “combat fatigue” was used during the Second World War. In 2013, a study focusing on US soldiers returning from Iraq and Afghanistan estimated that 20% of them experienced the disorder when they returned. But it is important to note that Post Traumatic Stress Disorder is not just about soldiers and veterans.

Returning to the original 1980 definition, a traumatic event is conceptualized as a stressor that is outside the range of normal human experiences. The authors of the concept assumed that torture, rape, the Nazi holocaust, the atomic bombings of Hiroshima and Nagasaki, natural disasters (such as earthquakes, hurricanes and volcanic eruptions) and disasters of human origin (such as factory explosions, plane crashes, and car accidents) were all traumatic events. Nowadays, we can also add to this list other events such as terrorist attacks. In particular, the authors of the concept considered that traumatic events were very different from normal life events, such as divorce, failure, rejection, serious illness or financial setback. In these cases, it is therefore possible to use the term “ordinary stressors” to characterize them. But what is important to note, and what makes all the difference, is the capacity of the human being to cope with the ordinary stress, notably thanks to its capacity of adaptation. Traumatic stress is far too strong for a person’s ability to adapt, and that’s why it is so dangerous.

PTSD is indeed unique among psychiatric diagnoses because of the great importance given to the traumatic stressor. In fact, a diagnosis of PTSD can only be made if the patient has actually been exposed to an event that is considered traumatic. But what about the symptoms? I quote the information page of the website of the famous Mayo Clinic in the United States: “Symptoms of Post-traumatic Stress Disorder can appear in the month following a traumatic event, but they can sometimes not appear before years. These symptoms cause significant problems in social or professional situations and in relationships. They can also interfere with the ability to perform normal daily tasks. The symptoms of PTSD are generally grouped into four types: intrusive memories, avoidance, negative changes in thought and mood, and changes in physical and emotional responses. The symptoms may vary over time or from person to person.”

The experience of diagnosing post-traumatic stress has, however, shown that there are individual differences in a person’s ability to cope with this type of stress. Therefore, while most people exposed to traumatic events do not develop PTSD, others develop the complete syndrome. The traumatic experience is filtered through cognitive and emotional processes before it can be considered an extreme threat. Because of the individual differences in this assessment process, different people seem to have different trauma thresholds: some are better protected while others are more vulnerable to developing these symptoms after exposure to extremely stressful situations. Although the aspects of traumatic exposure are subjective, it must of course be emphasized that events such as rape, torture, genocide and intense stress caused by war zones are experienced as traumatic events by almost everyone.

To conclude this episode of our podcast, it is interesting to note that since 1956 and the release of “The Stress of Life” by Hans Selye, many advances have been made about stress. Thus, no less than 300,000 articles have been dedicated to this subject, and our interest in it is far from weakening. In 1984, Susan Folkman and Richard Lazarus, both American psychologists, defined stress as “a transaction between the person and the environment in which the situation is assessed as overflowing an individual’s resources and endangering his well-being.” For a little less than a hundred years, the study of stress has aroused the interest of many disciplines such as physiology, psychiatry, psychology, neuroscience or endocrinology. But in the end, the study of stress is as subjective as the experience that individuals have of it, which makes it, as Alexandra Robinson says in her publication entitled Let’s Talk about Stress, “relevant and mysterious.”