Dr Eva Varadi: Neuro-physical response to stress

Our lives are full of stressful situations. An average person encounters about 2000 stimuli per day. They can encounter stressful situations anywhere, such as in their environment, at their work place, on the street, or in relationships. Additionally, it could be physical or mental stress. These stimuli can trigger stress hormones that produce physiological changes. A stressful incident can make the heart beat faster, breathing quicken, muscles tense and sweat to increase.

Unfortunately, the body can also overreact to some everyday stressors like traffic jams, work pressure, and family difficulties, even though these are not life-threatening. Over time, repeated activation of the stress response takes its toll on the body. Research suggests that chronic stress contributes to some physical symptoms (high blood pressure, formation of artery-clogging deposits, brain changes, obesity, sleeping difficulties) that may cause anxiety, depression, and addiction.

In our body we also experience some stress in the physical meaning. Stress is often a response to an external stimulus. This is demonstrated by the level of arousal, such as the sinoatrial node in our heart, our brain cells communicating with electrical impulses with each other, and the physical tension in our muscles. Stress increases this arousal level in our body when we feel stress input. We need to distinguish between physical and psychological stress, as well as positive and negative stress.

Physical stress: “either physiological or biological, is an organism’s response to a stressor such as an environmental condition”
Psychic Stress: “a conscious or unconscious psychological feeling or physical condition resulting from physical or mental ‘positive or negative pressure’ that overwhelms adaptive capacities”
Positive Stress: “helps improve athletic performance. It also plays a factor in motivation, adaptation, and reaction to the environment.”
Negative stress: which keeps us under pressure.

What happens in our brain and body?

The stress response begins in the brain (see illustration). When someone encounters a stressful situation or any danger, the eyes or ears (or both) send the information to the amygdala. The amygdala is the area of the brain that interprets images and sounds and contributes to emotional processing — it sends a distress signal to the hypothalamus in case of danger.

So that a person has the energy to survive, this area of the brain communicates with the rest of the body through the nervous system. Specifically, the hypothalamus is the area that communicates with the rest of the body through the autonomic nervous system (ANS). The ANS controls involuntary body functions such as heartbeat, breathing, and blood pressure.

The path of the signal is as follows:
1. the amygdala sends a distress signal
2. the hypothalamus sends signals through the autonomic nerves to the adrenal glands
3. the sympathetic nervous system is activated
4. the adrenal glands respond
5. the hormone epinephrine (also known as adrenaline) is pumped into the bloodstream and starts to circulate throughout the body
6. physiological changes happen: the heart beats faster, pushing blood to the muscles while pulse rate and blood pressure go up, and breathing quickens. Small airways in the lungs open wide, and oxygen-intake increases. “Extra oxygen is sent to the brain, increasing alertness. Sight, hearing, and other senses become sharper.” During this action the body reaches its best alert state ever.
7. the surge of epinephrine subsides.
8. the hypothalamus activates the HPA axis as well (hypothalamus — pituitary gland — adrenal glands) for maintaining the alert state.
9. the hypothalamus releases corticotropin-releasing hormone (CRH), which triggers the release of adrenocorticotropic hormone (ACTH) in the pituitary gland.
10. cortisol is released by the adrenal gland.

Thus the body stays on high alert. When the threat passes, cortisol levels fall and everything returns back to its normal state. It has side effects on the body, because “cortisol increases appetite, so that people will want to eat more to obtain extra energy. It also increases storage of unused nutrients as fat.”

These changes happen very quickly. People are not aware of them because they happen in their subconscious mind. That is why people are able to do things even before they think about what they are doing.

Musculoskeletal system

The body’s response to stress is muscle tension. Muscle tension is a reflex reaction to stress. This is about guarding against physical injury and pain. The difference between sudden onset stress and chronic stress is the time period. When we feel sudden onset stress, the muscles tense up all at once, and then release their tension when the stress passes.

Chronic stress causes a constant state of stress. In this case the stress is lighter but longer. When muscles are tense for a long time, this may cause other body reactions and even promote stress-related disorders. For example, chronic muscle tension in the area of the shoulders, neck, and head is related to tension-type headaches or migraine headaches.

A huge number of individuals suffer from chronic painful musculoskeletal disorders. Some individuals are fearful of pain and re-injury, and therefore they do not maintain enough physical activity. They seek only a physical cause behind their problems. They generally have a worse recovery than individuals who also consider the mental aspects, who have regular physical activity under medical supervision. Muscle tension can eventually promote chronic, stress-related musculoskeletal conditions.

Nowadays we know that relaxation techniques and other stress-relieving activities and therapies can help to effectively reduce muscle tension. These can decrease the incidence of certain stress-related disorders, like headache, and increase a sense of well-being, improve mood, and improve daily function.

Respiratory system

The task of the respiratory system is to supply oxygen to cells and remove carbon dioxide from the body. Stress and strong emotions can have respiratory symptoms such as shortness of breath and rapid breathing. For people who do not have respiratory disease, this is generally not a problem because their body can manage the extra work to breathe comfortably. But for individuals who have pre-existing respiratory diseases, psychological stressors can increase these breathing problems.

We know that some acute stress such as the death of a loved one. For instance, this can actually trigger asthma attacks for those who have asthma problems previously. Additionally, the rapid breathing — or hyperventilation — caused by stress can cause a panic attack in someone prone to panic attacks. Working with a specialist can help to learn relaxation, and calm breathing, and choose other cognitive behavioral strategies.

Cardiovascular

The task of the cardiovascular system is to provide nourishment and oxygen to the organs. Acute stress — that is, momentary or short-term — causes an increase in heart rate and stronger contractions of the heart muscle. Stress hormones have a great role in these situations — adrenaline, noradrenaline, and cortisol. When the acute stress situation has passed, the body returns to its normal state.

Stress increases heart rate — even if we are talking about positive stress or negative stress. Chronic stress can contribute to problems for the heart and blood vessels, such as long-term ongoing stress that can increase the risk for hypertension, heart attack, or stroke. This could be led by the repeated acute stress that could cause problems with the circulatory system, coronary arteries, and cholesterol levels. This is a pathway to heart attack.

Endocrine

When someone feels challenged, threatened, or out of control, the brain initiates a range of events through the hypothalamic-pituitary-adrenal (HPA) axis, which is the driver of the endocrine stress response.

At this point, cortisol levels start to go up. We often call it the “stress hormone”. During a stressful event, increased levels of cortisol can provide the energy required to deal with an extreme challenge.

The HPA axis

During times of stress, the hypothalamus sends signals to the pituitary gland to produce a hormone that sends signals to the adrenal glands to increase the production of cortisol. Upon awakening, the concentration of cortisol is higher and slowly declines throughout the day. Cortisol increases energy by mobilizing glucose and fatty acids from the liver.

Stress and health

Glucocorticoids, including cortisol, are important for the immune system. While this is valuable during stressful situations, chronic stress can lead to the deterioration of the immune system. All of this could be linked to the development of numerous physical and mental health conditions, including chronic fatigue, metabolic disorders (e.g., diabetes, obesity), depression, and immune disorders.

Gastrointestinal

The gut has hundreds of millions of neurons and bacteria. Neurons are in constant communication with the brain. Stress can affect this brain-gut communication, and may cause pain, bloating, and other gut discomfort. Additionally, stress is associated with changes in gut bacteria which can influence mood. The nerves and bacteria of the gut influence the brain and vice versa. Early life stress can affect the development of the nervous system and later the response of the body to stress situations.

Esophagus and stomach

Stress can make swallowing food difficult or it can increase the amount of air swallowed. This phenomenon can also increase burping and bloating. Additionally, stress can make pain, nausea, and other discomfort feel in relation to the stomach. Sometimes vomiting may occur. When individuals are in stressful situations, sometimes they eat much more or much less than usual. Last but not least, all unhealthy diets may generally spoil the mood.

Bowel

The bowel nerves are sensitive and their immune responses change under the influence of stress. Stress can make pain, bloating, or discomfort felt in the bowels. It can affect food moving through the body, which can cause either diarrhea or constipation, or spasms in the bowel. Gas production can increase.

Nervous system

The divisions of the nervous system:
1. the brain and spinal cord (central division)
2. the autonomic (sympathetic nervous system called SNS, and the parasympathetic nervous system called PNS) and somatic nervous systems (peripheral division)

The central nervous system regulates the autonomic nervous system. The autonomic nervous system plays a role in the physical response to stress. When the body is under stress input, the SNS contributes to the “fight or flight” response — it means exactly fighting off a life threat, or fleeing from a dangerous situation. The SNS stimulates the adrenal glands to release hormones called adrenalin (epinephrine) and cortisol (see Endocrine System). These hormones cause the heart to beat faster (see Cardiovascular System), increase respiration rate (see Respiratory System), dilate blood vessels in the arms and legs (see Musculoskeletal System), change digestive processes and glucose levels (sugar energy), and last but not least increase bloodstream flow to deal with the emergency (see Gastrointestinal System). When the crisis is over, the body normally returns to the pre-emergency, unstressed state. Stressors over a prolonged period of time can have long-term effects on the body. These drain the energy of body and soul continuously. In this case, the autonomic nervous system can cause wear-and-tear on the body. If activation of the nervous system is continuous, it can cause problems in bodily systems.

Sexuality and sexual desires

Ongoing or chronic stress over a long period of time can affect testosterone production. The consequence can be reduced libido and erectile dysfunction, which leads to impotence. Women have a lot of activities nowadays that require responsibility. These include jobs, family, goals, and decisions across their lives. These require attention and can lead to tiredness. Especially when women have a baby who needs daily care, and she has an ill relative. These can cause stress, depression, relationship difficulties, and work problems.

Reproduction and diseases of the reproductive system

Chronic stress can also negatively impact the reproductive system of both partners, including the members of the couple.

“Researchers have found that men who experienced two or more stressful life events in the past year had a lower percentage of sperm motility (ability to swim) and a lower percentage of sperm of normal morphology (size and shape), compared with men who did not experience any stressful life events.”
Stress also affects ovulation.

The reproductive system of both genders is influenced by the nervous system. The parasympathetic nervous system causes relaxation whereas the sympathetic one causes arousal. In the male anatomy, the “fight or flight” response produces testosterone and activates the sympathetic nervous system which creates arousal. When cortisol is released in the body, it has an effect on the blood pressure increase, circulation and male reproduction.

Stress also affects menstruation and pregnancy. Stress may affect menstruation in several ways. It affects absent or irregular menstrual cycles, more painful periods, and changes in the length of cycles. As for woman’s reproductive plans and ability to conceive, stress has a negative impact on both of them, and moreover the health of her pregnancy, and her postpartum adjustment. Depression is the leading complication in this phenomenon nowadays. Stress increases depression and anxiety during this time.

Maternal stress can negatively impact the development of the fetus, such as the child’s development in childhood and bonding attachment. Finally, we need to mention menopause. In this period, hormone levels fluctuate rapidly. This period is full of changes. Women can feel anxiety, stress, and mood swings. These feelings are difficult to cope with. It can cause physical symptoms to be worse. Menopause can be a stressor in itself.

Stress management

Nowadays we know a lot about stressors and symptoms, mental and physical health, and diseases. Many people cannot break stress. The main problem is that chronic stress keeps the HPA axis activated. Sooner or later this state will cause health problems.

But what can we do as prevention? What can support us in these kinds of situations? We need to get to know some techniques for stress management. My solutions are the following:
1. Healthy nutrition including daily eating and good quality food supplements.
2. Maintaining healthy relationships.
3. Regular physical exercises.
4. A sufficient amount of sleep each night.
5. Regular coaching or psychological sessions for prevention.

At this point I would like to mention Dr. Herbert Benson, director emeritus of the Benson-Henry Institute for Mind Body Medicine at Massachusetts General Hospital. He dealt with relaxation response techniques in his research and he helped people to apply them. Such as “deep abdominal breathing, focus on a soothing word (such as peace or calm), visualization of restful scenes, repetitive prayer, yoga, and tai chi.”

Some people who had hypertension or other heart disease took part in this research and were asked to evaluate how effective the relaxation response was against chronic stress. It seemed that it may be worth trying — although they were not healed by the techniques. Physical activity also can help people to decrease stress. For instance, taking a short walk after stress input can help breathing and relieve muscle tension. Movement therapies such as yoga, tai chi, and qi gong (mentioned above) are a combination of movements, deep breathing, mental focus, meditation, and concentration.

Besides, social support has been found very important. I mean relatives, spouses, friends, co-workers, confidants and so on. They are the ones who build up our life-enhancing social network. We do not have an explanation why, but those people who have close relationships with family and friends can battle better against health difficulties and diseases.

De Kloet said that hormones are able to elicit biological effects on different parts of the central nervous system and have an important role in behavior and cognition. McEwen’s hypothesis that stress can cause functional changes in the CNS was accepted. The effects of stress on the nervous system have been researched for about fifty years. These studies showed that stress has many kinds of effects on the human nervous system, including some structural changes in different parts of the brain (Lupien et al., 2009). We know from Sarahian that chronic stress can decrease the weight of the brain. Reznikov confirmed this.

To research the effects of stress is important because we need to learn to live with many kinds of stress input and stimuli. If we clearly know what happens inside our body, we will have the chance to handle this question seriously enough and have the possibility of thinking in terms of prevention.

Bibliography

1. Empson (1989) cited in: Rob Mclveen and Richard Gross (1996) Biopsychology, Hodder Arnold
2. Empson and Clarke (1970) cited in: Mclveen and Richard Gross (1996) Biopsychology, Hodder Arnold
3. Eysenck, H.J. (1988) Personality, stress and cancer: prediction and prophylaxis. British Journal of Medical Psychology.
4. Freud, S. (1909, reprinted 1990) Case study of Little Hans, in Sigmund Freud 8, Case Histories I. London: Penguin Books.
5. American Psychological Association (2019) Stress effects on the body, https://www.apa.org/helpcenter/stress-body
6. Harvard Medical School (2011, updated 2018) Understanding the stress response, Chronic activation of this survival mechanism impairs health, https://www.health.harvard.edu/staying-healthy/understanding-the-stress-response