Although stress wasn’t identified until around World War 11, it did exist. Nervous breakdowns, men coming back from war shellshocked, and homes for the bewildered give an inkling that stress existed, named or not.
In 1914 Harvard Professor of Physiology, Walter Bradford Cannon, coined the phrase ‘fight or flight’ syndrome. He observed physical changes in animals endangered by predators, including heart rate and decreased digestion. In the 1930s Austrian-born Canadian physician Dr Hans Selye identified three stages in the body’s response to stress: alarm, resistance and exhaustion. It is the second, and particularly third, stages that reveal the physical manifestations of the ill effects of stress.
A useful definition of stress is ‘the actual or perceived threat to wellbeing’
Stressors need not be physical, and indeed most 21st-century stress comes from a psychological perception of ‘threat to wellbeing’, with the physical stressors being less obvious in the form of chronic pain or illness.
The two main stress hormones, adrenaline and cortisol are produced within the adrenal glands, from the medulla and cortex respectively. Adrenaline is the better known ‘show pony’ of the two, whereas cortisol is more silent and stealthy, and in my opinion the one to be more feared from the health perspective. Adrenaline’s effects on the body are often compared to ‘fight or flight’ response our forebears would have experienced in the prehistoric jungle. The following table summarises these effects.
|Body part|Sympathetic nervous system response when stimulated by adrenaline. Adrenaline causes the body to respond to stress in the fight/flight mode, just like running or fighting in the prehistoric jungle| |Eye (pupil)|Dilated (to see in darker places like the jungle)| |Sweat glands – general|Copious sweating| |Apocrine gland (underarm and groin)|Odiferous secretions – smelly sweat| |Lungs (bronchi)|Dilated (making it easier to breathe when you are running away from T. Rex) In an emergency adrenaline is injected to relieve asthma attacks because it widens the breathing tubes.| |Digestive system|Decreases peristalsis (the normal downward movement of the digestive tract) total lack of muscular tone will cause diarrhoea| |Penis|Ejaculation – adrenaline IS exciting| |Skin|The blood vessels to the face and outer parts of he body become constricted – blood drains from the face ‘you look as white as a ghost’ while blood goes to more important places like legs for running.| |Metabolic rate|Increases by up to 100%| |Piloerector muscles (muscles around the hair roots)|Contracted – goosebumps| |Blood vessels|Constricted – heart attack or angina material.| |Kidneys|Decreased output – no time for a wee| |Blood|Increased coagulation (so blood can clot, and we don’t haemorrhage to death in case of goring), increased blood glucose (for muscle energy), increased blood fats (for muscle fuel)| |Mental activity|Increased. You’d best have your wits about you in a fight to save your life.| |Skeletal muscles (legs etc)|Strength increased. All the better for running. In times of great stress we can lift far greater weights than normal. You hear stories of fathers lifting a car if they think their child is trapped underneath.|
Cortisol is secreted at the same time adrenaline is. It’s purpose is to reduce inflammation. However, cortisol is also secreted with more chronic stressors. See below
Some of the different types of stress that increase cortisol release are:
The effects of hypersecretion of cortisol on the body are:
Cortisol is created from cholesterol, and cannot be stored, so that when in demand we need to create more cholesterol or use from dietary source, which may explain why blood cholesterol levels can be high in stressful times.
Peak cortisol levels 2-4 hours after waking with it’s nadir at around 11pm. (Corticosteroid therapy more effective given at midnight rather than noon) Controlled by dark/light, sleep/wakefulness, also food.
Basal production 30mg every 24 hours up to 300mg in stressful conditions. (Despite similar 24hr mean concentration, rats with significantly elevated trough levels of corticosterone show evidence of insulin resistance and immune suppression. Jacobson.)
Ideally cortisol acts as a negative feedback; however, if chronic stress then increased cortisol all the time.
Chronic ACTH stimulation causes an increase in size, cell number and secretory activity of adrenal cortex cells.
High levels of cortisol interfere with memory. If the stress is short term (ie less than 6 months) the effect is not permanent, and memory will return to normal once cortisol levels drop. However, repeated and long-term stress can atrophy or shrink the hippocampus the very part of the brain where we store memories.
Cortisol affects long-term memory more than short-term recall. You can still learn under stress, but it’s harder to recall after 24 hours.
We are able to create new brain cells all our lives, they don’t have to diminish with age. However, in a study by the American National Institute of Health it showed that cortisol, significantly reduces our bodies ability to grow new brain cells.
A study reported in the International Journal of Neuroscience found that high stress levels could be linked with the onset of Alzheimer’s disease. Research into drugs that lower cortisol levels is being pursued.
Cortisol reduces protein synthesis, and increases protein breakdown. This translates to loss of muscle tissue and poor wound healing. With lots of stress our muscles get weak and lose tone, also increasing risk of osteoporosis.
Stress is more powerful than diet in influencing cholesterol levels. Several studies including one of medical students around exam time and another of accountants during tax season, have shown significant increases in cholesterol levels, when there was little change in diet. Dr. Paul Rosch, Professor of Medicine New York Medical College)
Severe stress is one of the most potent risk factors for stroke, even 50 years after the initial trauma. In study of 556 WWII veterans, the rate of stroke among those who had been prisoners of war was 8 times higher than among those not captured.Alan Young MD Cardiologist Harvard Medical
Chronic stress linked with increased platelets and fibrinogen, high cortisol levels increase aldosterone, (increasing blood volume and pressure), Excess cortisol increases High Density Lipid ratio and Increases BMI. MI waiting to happen!
Elevated cortisol increases insulin production. With a chronic elevated cortisol, there is an increase in abdominal fat, which is a risk factor for heart disease and diabetes.
When cortisol is secreted, so is aldosterone, which causes an increase in fluid retention.
Elevated cortisol decreases glucose uptake into cells and thus glucose utilisation. Cortisol is diabetogenic, either aggravating existing diabetes, unmasking latent diabetes or causing insulin resistance.
Acute stress i.e. no more that 3-5 days can increase immunity battle stations, in the middle of a crisis, you rarely get sick, but the minute the alarm bells have finished you are wide open to infection.
Longer-term stress with its higher cortisol output decreases the number of immune cells – eosinophils and lymphocytes in the blood. In addition large doses of cortisol causes significant shrinkage of all the lymphoid tissue (the lymph is where the immune cells mature and travel) throughout the body, which in turn decreases the output of both T cells and antibodies. As a result the level of immunity for almost all foreign invaders of the body is decreased.
This ability of cortisol to suppress immunity makes it of use to prevent immunological rejection of transplanted hearts etc. explains why transplant patients are at risk of getting infections.
A study looked at one marker of the immune system – S-IgA (Salivary immunoglobulin) found in mucosal secretions. It is the first line of defence against pathogens in mouth and gastrointestinal tract, urinary tract and throat and lungs. The study showed various videos to the participants. One video was of Mother Theresa doing work with the dying in India. The participants noted feeling of love, compassion, and tranquillity and lo and behold an immediate increase in S-IgA was observed. S-IgA will increase in positive mood states. Then a ‘feel bad’ violent video was shown and the participants noted feelings of frustration, aggravation and resentment, and the S-IgA levels fell.
In yet another study 400 people were exposed to the cold virus. It is often the strength of our immune system that decides whether we ‘catch’ viruses. Otherwise everyone would catch every virus. Those who scored highest on the test of stressful life events were more than twice as likely to develop colds after exposure than people who scored lowest.
A study in 2000 in the Journal of the National Cancer Institute found that cancer patients with high stress levels were less likely to live as long as patients who coped well with stress. Although no one knows the reason for cancer, a healthy immune system is better equipped to kill cancer cells as they are formed.
Rats unable to escape electric shocks had earlier tumour appearance and decreased survival time compared to rats who could escape.
High proportion of depressed patients show elevated cortisol, evidence that high cortisol may contribute to depression rather than being a reflection of the disease. Jacobson
Stress is a fact of life. Learning to manage it well can help to prevent or treat a number of illnesses. Each person needs to find the combination of modalities/treatments which suits their lifestyle and personality.
In most cases you need to treat the presenting symptom eg insomnia, overweight as well as the underlying stress.
Key treatments include:
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p(note). Larsen Williams Textbook of Endocrinology, 10th Ed. 2003 Elsevier (via MD consult website) Adrenal Cortex and Endocrine Hypertension, Adrenal Steroids and Steroidogenesis
p(note). Mills, Simon; Bone, Kerry. Principles and Practice of Phytotherapy Modern Herbal Medicine Churchill Livingstone (Harcourts) 2000
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p(note). Reiche, Edna Maria Vissoci; Nunes, Sandra Odebrecht Vargas; Morimoto, Helena Kaminami; Stress, depression, the immune system, and cancer The Lancet Oncology Volume 5 Number 10 October 2004
p(note). Vicennati, Valentina; Ceroni, Luana; Gagliardi, Lorenza; et al. Response of the Hypothalamic-Pituitary-Adrenocortical Axis to High-Protein/Fat and High-Carbohydrate Meals in Women with Different Obesity Phenotypes Journal of Clinical Endocrinology and Metabolism Volume 87 Number 8 August 2002
p(note). Von Hertzen, LC Maternal stress and T-cell differentiation of the developing immune system: possible implication for the development of asthma and atopy J Allergy Clin Immunology 01-JUN-2002; 109(6): 923-8
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