Stress has
become a word used colloquially in many circumstances of minor or major
complaints. An annoying person is a ‘stress’, work is ‘stressing’,
the weather can be ‘stressful’ etc. It is a common saying but it is all also
anatomically true; all these are real stresses, or better, stressors. The use
of the word stress in biology and medicine is precise and indicates a ‘response
to any threat to life or wellbeing’
(therefore the pressure at work would be a threat
and the persistent rain another one).
Stress can be brought on by either physical
strain (the stressor): a long run, exposure to toxins or environmental poisons,
heat or cold; or by emotional strain: a divorce, a move, a marriage,
bereavement, academic pressure, loosing a job, deadlines at work, etc. The physical and physiological
reaction is identical in the two cases. Stressors of both types elicit a
sequence of reactions by the body, which is called the “stress response” or “fight-or-flight
response”. We learned this type of reaction when humans had to face attacks
from ferocious predators or had to survive in face of extreme conditions (life
in a cave, hunting in a jungle). Although most humans don’t face such threat
anymore, the reaction to modern life stressors (traffic jams, playing a rugby
match – or sometimes just watching it!-, buying a house) has remained the same.
The fight-or-flight response is initiated by nerve impulses from the
hypothalamus (a part of the brain that controls most involuntary responses like
body temperature, hunger, fatigue, attachment behaviors etc.); such nerve
commands reach the adrenals (glands that sit on the kidneys) directly, stimulating
release of adrenaline and noradrenaline, which increase heart rate, blood
pressure and breathing rate: they get the body ready to fight or to run. Impulses
from the hypothalamus reach also the endocrine (hormonal) system, via the
hypothalamus-pituitary tract, to stimulate the pituitary gland (or hypophysis) and
the adrenals again. The adrenal glands, stimulated both by the nervous system
and by hormones, release cortisol (the major stress hormone), which, along with
the growth hormone released by the pituitary gland, stimulates catabolism or
production of glucose, aminoacids and fatty acids from fat stores and proteins
to provide the necessary energy for movement (fight or run), repair or defense.
The pituitary gland also promotes the secretion of thyroid hormones T3 and T4
that increase use of glucose as well, while the insulin response (insulin is
the hormone needed to store glucose inside the cell) is shut down so that
increased sugar can remain in the blood ready for energy need. Pancreatic
release of insulin is thus depressed.
All these reactions aim to put the body in action with increased
breathing, increased heart rate, increased muscular contraction needed for the
fight or for the flight in front of the threatening predator or office boss or
running competitors. At the same time the activity of the digestive, urinary
and reproductive systems, quite useless in those situations, is depressed.
Stress
in moderation is not harmful and can be necessary as an incentive in some
actions (positive stress or eustress),
like getting ready to win a match.
However, when
stress is prolonged, repetitive and not dealt with, it can become harmful and
lead to diseases: constant stress in fact brings hormonal changes in the body,
lowers the immune functions and can lead to many diseases including auto-immune
diseases. It is the individual response to stress that can make a difference
between a healthy happy life and a miserable life threatened by chronic
illness. This is because it is not the
type of stressor that initiates a response but the “perception” of such a
stressor by the individual. The perception of an experience determines how we
feel when it is happening and how our bodies will be affected (Martino, 2011). What
is terribly difficult to endure for one person can be easily managed without
consequences by someone else.
Since
constant or repetitive stress can have adverse effects on the body, in order to
avoid stress-induced illnesses one should become more relaxed about life and always
try to see issues in perspective. Since avoiding stress is rare or impossible,
it is important for all to apply measures to release the tension: deep
breathing, relaxation techniques, massages, cardiac coherence etc.
How does stress cause
disease? Stress has impact on the nervous system, the immune system and the
hormonal system. In an emergency situation immediate responses from these
systems are needed, but in an unnatural prolonged state of stress they harm the
individual. A physical or psychological stress affects the functioning of cells
and can have long-lasting influences on physiology and behavior.
- Impact on the nervous
system: prolonged or repetitive stress can lead to physical changes in the
brain, such as shrinking of the amygdala (center of emotions, decision making,
memory) or the hippocampus (memory). Learning, memory and behavior are thus affected.
- Impact
on the immune system: it is well accepted and understood how a psychological
stress is directly correlated to the prevalence of diseases such as infections.
The immune cells have receptors for the hormones released during the stress
response by the adrenal glands, the pituitary gland and the autonomic nervous
system: cortisol, adenocorticotropic hormone, endorphins, noradrenalin, growth
hormones, prolactin all influence the immune system. This explains the
mechanism of the direct effect of stress on the immune system functioning.
Cortisol triggers an increased “innate immune response” represented by high inflammation,
a high allergic response, an increase in viral infections and a higher cancer
risk. These are responses that you do not wish on a long term. (As a comparison,
therapeutic cortisol (cortisone) instead lowers inflammation and suppresses
immune and allergic reactions).
- Hormonal system: a
continuous stress or a frequent presence of even smaller stresses drain the
adrenal glands from which the main stress hormone, cortisol, is released.
Prolonged stress can also lower the level of sex hormones like oestrogens and testosterone.
Pancreatic production of insulin is interrupted and this, on the long run, can
lead to diabetes type 2.
As
many as 80% of all major illnesses have been related to stress as a contributor.
Chronic
stress, especially through the high level of cortisol released, causes wasting
of muscles, suppression of immune system (by cortisol, which suppresses part of
the immune system), generation of auto-immune diseases (like rheumatoid
arthritis, lupus, multiple-sclerosis), cancer, hyperlipidemia (high fat content
in the blood and wrong types of fats),
atherosclerosis, increase of cholesterol, hypertension, hyperglycemia, diabetes
mellitus, abdominal obesity (metabolic syndrome), osteoporosis, mood-behavioral
changes, ulceration of GI tract (peptic ulcer, liver damage, irritable bowel syndrome,
and ulcerative colitis and Chron’s disease, which are precursors of colorectal cancer), insomnia, anxiety,
depression.
Stress
is a significant factor also in the birth of certain psychiatric disorders such
as depression and anxiety.
Anxiety is one of the most serious emotional
manifestations of stress and is caused by expectations
of anything that threatens a person’s body, job, loved ones, values. It occurs
in situations perceived as uncontrollable or unavoidable, but that are not really so. It is a state of
inner apprehension, often accompanied by nervous behavior, like pacing back and
forth, foot tapping, teeth grinding etc.
Anxiety can also be a response to a past mismanaged stress.
Symptoms of stress are high blood pressure, neck-ache, backache, muscles
tension, muscle twitching, being unable to sit still or relax, fatigue,
insomnia, lack of concentration, teeth grinding, nail biting, suppressed anger,
feeling unloved, lack of self-esteem, low sex drive, irritability, tearfulness,
loss of appetite or overeating, constant anxiety, frequent infections, allergies,
blood sugar disturbances appearing with irritability and sugar cravings.
As many as 77% of people in
Western countries complain of stress, and many are related to work. Many young
people (younger than 18 years of age) are affected by stress. Some people are
stressed but they are not aware of it, but the consumption of their teeth for
example is testimony of it. Alert!
Stress also causes body mineral
changes: it causes sodium retention, which in turn increases blood pressure.
Adrenalin also causes a loss of Mg, Ca (from the bones), K and P. Also, during stress, nutrients
are not efficiently absorbed. A nutrient deficiency is thus created with
deleterious consequences for many organs. Many of the diseases related to
stress are not due to stress alone but to the loss of nutrients: vit C, K, P, B and minerals.
Some
people are more at risk of chronic stress depending on their genetic pattern
but also on their innate and acquired inability to face challenges and respond
properly to increased demands from work, financial issues, surgery or
illnesses, society, pollution (noise, atmospheric, toxins), allergies, etc. Nutrient
deficiencies from other causes, like improper nutrition, ex lack of B vitamins
or Mg, make an individual more at risk of succumbing to chronic stress. Age,
gender, social status, social support, religious/spiritual beliefs, personality
traits, self-esteem, past experiences are all factors contributing to such
susceptibility.
Again, there are many tools that help in
learning to managing and coping with repetitive stress: regular exercise, both moderate
low-intensity aerobic exercise to boost immunity (too much exercise increases
inflammation) and physical practice that balances the immune system reactions and
boost an antibody response (suppressed in stress condition): walking, jogging,
biking, yoga, tai chi, chi gong; relaxation, breathing practice, like cardiac
coherence or pranayama (yoga breathing exercises), meditation and massage are
all useful tools that should be relied upon on a regular basis to improve the
reaction to stressors.
Stress: "The
best care for the body is a quiet mind". Napoleon.
Bibliography
Mifsud KR1, Gutièrrez-Mecinas M, Trollope AF, Collins A, Saunderson EA, Reul JM., Epigenetic mechanisms in stress and adaptation.Brain Behav Immun. 2011 Oct;25(7):1305-15. doi:
10.1016/j.bbi.2011.06.005. Epub 2011 Jun 14.
Craft, J.,
Gordon. C., Tiziani,. A.
et al. 2012 Understanding Pathophysiology, Elsevier, Houston pub.
The Free Library, 2009. Exercise
is medicine: using exercise to manipulate TH1 and TH2 immune function. The Townsend Letter Group 06 Jul. 2014 http://www.thefreelibrary.com/Exercise+is+medicine%3a+using+exercise+to+manipulate+TH1+and+TH2+immune...-a0202661767
