The InterRelationship between Stress and the Human Essay

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The InterRelationship between Stress and the Human Immune





The Inter-Relationship between Stress and the Human Immune
System upon Health Outcomes
By Luke Austin

The impact of stress on human immune system functioning and health outcomes is an area of
recent interest. This investigation as to how health outcomes are affected by this
inter-relationship will firstly operationalise all of the variables (health, stress,
immune system); and secondly, by describing the functions and reactions of the immune
system to clinically induced stressors, establish that there is a correlation between
stress and immune response. The final area of investigation will discuss how the human
body, when exposed to a variety of stressors, causes major changes within the immune
system (which can be scientifically measured), and thus affect health outcomes. How groups
are affected throughout the life span continuum will be discussed, with particular
reference to women diagnosed with breast cancer, HIV gay men, and the impact of
personality types deemed to be at greatest risk.


Stress, as defined by Selye (1960), is namely "the non-specific response of the body to
any demand made upon it; a stereotypical, phylogenetically old adaptation pattern,
primarily preparing the organism for physical activity" (cited Gunderson and Rahe, 1979,
p. 9). The current scientific paradigm asserts that stress has three distinct
characteristics.


External stress refers to any or environmental stimulus that causes a person to feel tense
or aroused. Internal stress refers to the subjective mental state of tension or arousal,
and involves the interpretive, emotive, defensive and coping processes occurring inside
that person. The third characteristic of stress involves the body's physical reaction to
demand or demanding intrusions (Rice, 1999). Baum argues that the primary functions of
these physical reactions are to support each individual's behavioural and psychological
response in relation to stress (1990, cited Rice, 1999).


There are two main categories of stress: acute and chronic. Acute (or external) stressors
include films, work overload, unexpected or uncontrollable noise, prestige or status loss,
electric shock, uncontrollable situations, physical illness, surgery, threats to
self-esteem, and traumatic experiences. Examples of chronic stressors include sleep
deprivation, role strain and social isolation (Elliott and Eisdorfer, 1982). Chronic
stress within an individual is often associated with negativity, and the observable
physical manifestations include exhaustion, disease and even death (Rice, 1999).


Individual differences in responding to stress are influenced by genetics, developmental
and environmental influences, as well as being linked with one's own life experiences
(McEwen and Stellar, 1993). However, stress does cause some common changes. Emotionally,
stress can lead to feelings of depression, anxiety and anger (McEwen et al, 1993).
Accordingly, on the basis of the above criteria, it is clear that stress has a direct
correlation on health outcomes.


In order to assess the interaction between stress, the immune system and health outcomes
it is necessary to operationalise the contextual meaning associated with health in this
instance. Stedman's medical dictionary (1961) defines disease as "an interruption or
perversion of function of any of the organs and/or tissues or an abnormal state of the
body as a whole" (cited Newberry, Jaikins-Madden and Gerstenberger, 1991, p. 23). Weiner
(1977, p. 11), using Stedman's criteria, suggests "illness" is a synonym of disease and
"health" as the absence of disease (cited Newberry et als., 1991).


By contrast Schwartz (1984) has distinguished between the current state of the organism
and its potential to resist disease. In his terminology, "wellness" refers to the current
state and "health" refers to the potential to be well. Thus people can be diseased (low
wellness) yet be healthy if they are exhibiting resistance to the pathology and healing
successfully. Conversely, a person can be well (not diseased) but still be unhealthy
(cited Newberry et als., 1984). The importance of Weiner's construct between disease and
illness in crucial to this argument, as it raises the issue of behaviour as an outcome
variable in stress-disease studies (Newberry et als., 1984).


The immune system constitutes a major defense against infectious organisms and possibly,
to a lesser extent, against cancer. It is now beyond dispute that the immune system is
affected by neuroendocrine factors and stress-related psychologic variables (Newberry et
als, 1984). For this reason, and because of its role in host resistance to numerous
disorders, the immune system has received a great deal of attention as a possible mediator
of the stress-disease relationship (Newberry et als, 1984). It is the immune system which
protects the body from disease organisms and other foreign bodies, known as antigens. The
first line of defense are local barriers such as the skin, peritoneum, etc, and
inflammation due to immunoglobulins, or antibodies. If these fail to block or destroy the
antigens, the cell-mediated immune and humoral immune responses takes over (Gallagher,
Gilder, Nossal and Salvatore, 1995).


The cell-mediated responses use sensitised T cells (white blood cells derived in the
thymus) to recognise, attach to, and render antigens inactive. Other types of T cells,
called helper T cells, aid in production of antibodies by B (bone marrow) cells, and
suppressor/cytotoxic T cells, (which inhibit that production), are also essential for
proper immune system function. Helper T cells are known as CD4 cells, and suppressor T
cells are known as CD8 cells (Kiecolt-Glaser, Cacioppo, Malarkey and Anderson, 1992).


Immunocompetence is the degree to which the immune system is active and effective (Rice,
1999), and it is the ineffectiveness of the immune system which is used to measure, in
this discussion, the inter-relation between stress and health outcomes. Up until the early
1980's, it was generally acknowledged by the then dominant scientific paradigm that the
immune system was an auto-regulating one, working with minimal input from the central
nervous system (CNS).


Robert Ader (1983, p. 251) established that "the immune system is integrated with other
physiological systems, and thus sensitive to regulation or modification by the brain"
(cited Rice, 1999). Pinel (1993) elaborated on Ader's research showing that "as
psychosocial stressors occur, neural cascade beings, a process which involves the
hypothalamic-pituitary-adrenal (HPA) complex" (cited Rice, 1999).


The corticotrophin-releasing factor (CRF) hormone is released by the hypothalamus, which
in turn causes the anterior pituitary gland to release a hormone named
adrenocorticotrophic (ACTH). This stimulates the adrenal cortex to secrete steroid
hormones called glucocorticoids (Pinel, 1993, cited Rice, 1999; Kiecolt-Glaser et als.,
1992). The primary purpose of this response is to contain (short term) the stress
reaction, and in so doing avert damage to itself. However, in response to higher-level
stressors, glucocorticoids negatively impact, resulting in suppression of the immune
system (Rice, 1999; Brosschot, Benschop, Godaert, Olff, DeSmart, Hgeiinen and Ballieux,
1994). Thus the likelihood of resulting illness is increased, due to the immune system
being weakened.


Ader's findings also provided researchers with credible and convincing evidence in
relation to the influence of conditioning on the immune function, and the relationship
between psychosocial factors, (such as life stress) and immunocompetence. (Rice, 1999).
Immunocompetence, as described by Rice, is the "degree to which the immune system is
active and effective" (1999, p. 142). Studies by Manuck, Cohen, Rabin, Muldoon and Bachen
(1991) showed that:


Psychological stressors induced cell division among CD8 cells, thereby increasing the
number of CD8 cells and suppressing immune function. Individuals fall into
categories…..those who are "high reactors", and those who are "low reactors". High
reactors are significantly affected by stress, as shown by a significant increase in heart
rate, blood pressure, catecholamines, and CD8 cells. Low reactors show little or no change
in those areas (p. 111).


Catecholamines are chemicals produced by the body that work in nerve transmission. The
three main catecholamines include dopamine, epinephrine and norepinephrine. Dopamine
raises the heart rate and blood pressure, epinephrine raises heart rate and opens blood
vessels (thereby lowering blood pressure); and norepinephrine closes blood vessels
(thereby raising blood pressure) (Glaser, 1996). Epinephrine and norepinephrine are the
catecholamines most commonly measured in stress experiments, and both increase under
stress.


Increases such as these can suppress aspects of immune function, including natural killer
cells (cells that attack antigens without having recognised them first) activity.
Increases in catacholemines may also rapidly alter cell numbers via redistribution.
Changes in epinephrine levels are also thought to reflect lymphocyte migration from bone
marrow, the extremities, and the thymus to other parts of the body (Gallagher et als.,
1995; Naliboff, Benton, Solomon, Morley, Fahey, Bloom, Makinodan and Gilmore, 1991).


All of the above supports the argument that there is an inter-relationship between stress
and immune system functioning, and that this interaction can be measured. Or to word it
another way, there is a clear causal relationship between the cognitive (stress in this
case being the manipulated independent variable), and the physiological (the immune system
which is being manipulated). Any variable which affects the normal immunocompetence of
the immune system (wellness), thus impacts on health outcomes (illness/low wellness).


Much anecdotal evidence is available in relation to psychoneuroimmunology (the interaction
between psychological and immune variables). Wolf, Cole and Coyne (1996), undertook a
statistical investigation to look at clustered psychological, health and immune variables
using canonical correlation techniques. Canonical correlation is a multi-variant
correlation technique for relating two separate domains where multiple measures exist
within each domain.


The results indicated that it was possible to identify specific indices of human stress
response which correlate with specific and non-specific components of immune response.
Wolf et als. (1996) concluded that in the case of the non-specific (inflammatory) immune
component: "there was a statistically significant correlation between psychologic indices
of stress and non-specific immune functions" (p. 9). Loneliness and helplessness
represent a stressful condition that can be correlated with a non-specific immune response
(Wolf et als, 1996).


Younger, more obsessive-compulsive and more exercising individuals raise the possibility
of increased tissue macrophage and mast cell activity. They were intrigued to note that:
"suppressed hostility (obsessive-compulsive) is associated with enhanced cellular immunity
while overt hostility is associated with enhanced humoral immunity" (Wolf et. als., 1996,
p. 11). This study is impressive in its findings as the association between psychology,
immune variables and health outcomes is deemed to be significant, and not the result of
chance (p less than .038, to p less than .006) (Wolf et als., 1996).


Strong relationships seem to exist between an individual's disease patterns and their
personality type, and may negatively influence the health of that person. Eysenck suggests
that various types of personalities are predisposed to particular illnesses. His is a
biological based theory, which takes into consideration, and allows for, social influences
(Wade and Tavris, 1993).


As defined by Eysenck, the type one personality tends towards hopelessness, helplessness
and suppression of emotion; and are prone to cancer (Hassed, 1998). Those categorised as
type two experience anxiety, aggression, ambition and they express emotion
inappropriately. These people are more prone towards heart disease. By contrast type three
are sensitive and gregarious. They communicate better, tend to be optimistic, and are able
to remain calm under stress. These individuals have significantly fewer illness,
especially cancer and heart disease (Hassed, 1998).


Hassed undertook two longitudinal studies aimed at testing Eysenck's hypotheses. The first
showed that individual's with type three personality lived longer, and that cancer or
heart disease being the cause of death was significantly decreased (Hassed, 1998).


Of particular interest is Hassed's second longitudinal investigation, carried out over
seven years, involving 490 cancer and heart disease prone individuals. The group that
undertook a six months autonomy training program (therapy group), when followed up seven
years later, had a death rate of only 20%. The group that received no therapy (control
group), at the end of seven years, had a death rate of 76%. Especially in relation to
cancer prone individuals, Hassed's findings clearly show that the effects of stress
(exhibited through hopelessness, helplessness and suppression of emotion) upon the immune
system (cancer) influence health outcomes (in this case positively).

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