Biology 202
2004 First Web Paper
On Serendip

In the ethnographic study of disability, the subject shifts from THEM to US, from what is wrong with them to what is wrong with the culture that history has made for all of us, from what is wrong with them to what is wrong with the history that has made a THEM separate from an US, from what is wrong with them to what is right with them that they can tell us so well about the world we have all inherited. (1)

This study, the first of three papers, is intended to shed light on the effects of psychosocial factors on the human body and their influence on health. It will explain the physiological basis upon which the environment and society can promote poor health. Disability and pathology are symptoms of deeper problems; disease is the end product of malfunctioning systems. In the interest of better understanding the etiology of disease in human beings, we must recognize the many complex interacting systems that contribute to health and epidemiology. For this, we must take a step back and consider basic questions such as "What is health?". As defined by the World Health Organization, "health is a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity" (2). In this definition, accepted by most countries in the United Nations, physical well-being is clearly only one of several factors that constitute good health. So let this be our point of departure, and let us ask next what problems face global health.

Ironically, poverty is still considered the number one problem linked with poor public health around the world. There seems to be a wide gap between the WHO's definition of health and how health is actually being approached. As society is becoming more technologically advanced, the focus is shifting to a Bio-medical Model. With this specificity, the problem of health today may be that of limited perception. Our society seems to have forgotten the principles from which it has departed on the quest for "Healthy People". For example, the World Health Report 2000 found that despite the fact that the U.S. health system spends a higher percentage of its GDP than any other nation, it ranked 37 out of 191 countries according to its overall performance (3). In 2003, the Census Bureau recorded more than 43.6 million Americans with out health insurance (4). These absurd paradoxes of our society are grave symptoms of malfunctioning political and economic systems. Yet, these figures are often forgotten because of excessive specialization on the physiological aspects of health. Therefore, we need to reconsider the larger point of view, and the many variables that affect the health of individuals and populations. Just as the WHO's definition suggests, psychological and socio-economic well-being are essential to the overall formula of health.

It is the awareness and integration of these "global" factors that we will attempt to introduce with PsychoNeuroImmunology. This field studies the interactions between the mind, the Nervous and the Immune Systems. PsychoNeuroImmunology will help us establish a bridge between the material (biological and physiological) factors and "non-material" (societal, economical, political) factors that affect health and disease. The Nervous System, the brain in particular, is at the center of those interactions. It is the principal link between the mind (or the mental state) and the body's immune system. There are several existing models that try to map these complex interactions. For example, Kemeny's X-Y-Z model investigates the linkages between psychological processes, physiological mediators and disease progression (5). Kemeny indicates that "the brain is the most proximal physiological substrate through which psychological factors act on peripheral neural systems [...] to affect pathophysiological mechanisms and clinical disease" (5). Another model where the Nervous System is at the heart of the interacting factors is Costanzo's Biopsychosocial Model (6). This is a more complete model, integrating the psychosocial, biological and behavioral catalysts on health. According to the Biopsychosocial Model, these factors affects, via stress, the Neuroendocrine and Immune Systems, which in turn determine disease vulnerability and progression. Thus, by mapping those interactions, it provides us with the mechanisms of mind-body relations in disease. Castanzo asserts: "Interactions between psychosocial and immunologic factors are relevant to a variety of diseases including inflammatory diseases, cardiovascular disease, infectious diseases, cancer, diabetes, osteoporosis, muscle wasting, and multiple sclerosis, and processes such as wound healing, surgical recovery, and efficacy of vaccination" (6). It is true that various longitudinal studies have shown stress to be strongly related to heart disease, especially among people of low socio-economic status. Also, loneliness and social isolation have been linked to increased morbidity and mortality. In order to approach these issues, we will start by examining the mechanisms of interactions between the NeuroEndocrine and Immune Systems.

The "non-material" factors on health (psychological, social, economic and political) can affect the human body by inducing change in the physiological systems. This change is brought through by the working of the NeuroEndocrine and Immune Systems, and their effects on the rest of the body. Environmental events that are challenging, uncontrollable or unpredictable activate the body's stress or "fight-or-flight" response. This response triggers physiological and behavioral changes in taxing or threatening situations (7). The Sympathetic Nervous System promotes the release of hormones that affect both the Nervous and Immune Systems. "A key hormone shared by the central nervous and immune systems is corticotropin-releasing hormone (CRH); produced in the hypothalamus and several other brain regions, it unites the stress and immune responses" (7). CRH causes the pituitary gland to release adrenocorticotropin hormone (ACTH), which triggers the adrenal glands to make Cortisol. The HPA axis is composed of the Hypothalamus and the Pituitary gland, located in the brain, and the Adrenal glands, which lie above the kidneys. The HPA axis and its key hormone Cortisol, are major components of the NeuroEndocrine stress response. "Cortisol is a steroid hormone that increases the rate and strength of heart contractions" (7). Cortisol is also an immunosuppressor, a potent immunoregulator and anti-inflammatory agent. This is a key point, because this arousal is thought to be a mechanism by which the stress response affects health. It causes an increasing "wear and tear on bodily systems, and damage to arteries, neural systems, and organ systems, and reducing resistance to pathogenesis" (8). This emphasizes the inter-dependence of the nervous and immune systems, and indicates that the malfunction of their regulating mechanisms can have serious consequences on health. "The adoptive responses may themselves turn into stressors capable of producing disease" (7). Therefore, stress can have negative outcomes on health by dampening the functioning of the immune system and increasing the body's susceptibility to infections and diseases. "The regulation of the immune system by the neurohormonal stress system provides a biological basis for understanding how stress might affect these diseases" (7). It is upon this basis that we will develop the understanding of how psychosocial stress promotes pathology. For example, the feeling of loneliness in humans is associated with an adrenaline-like pattern of activation of the stress response and high blood pressure (7). Our attention will turn to such psychosocial catalysts of disease.

The disparity between the Bio-medical Model and public health is evidence that the integration of all the variables affecting health is lacking and needed. The Biopsychosocial Model is more comprehensive, and will thus help us in our approach to the problem of mind, society and wellness. PsychoNeuroImmunology gives us a physiological basis upon which we can build the mechanisms of how social interactions, or the lack there of, can affect health, for instance. In the next paper, we will explore stress and its correlation with socio-economic status. As we depart from the biological basis to the "non-material" influences on health, we will begin to attain a wider picture of what well-being means. It will eventually make it possible and meaningful to raise certain questions as "Do certain economic systems promote disease? Does a healthy economy necessarily mean a healthy population?"

Sources:

1)Culture as Disability, By Ray McDermott and Hervé Varenne. Serendip website.

2)World Health Organization

3)World Health Report 2000,WHO archives.

4)AMA decries rise in number of uninsured Americans, American Medical Association. Sept. 30, 2003.

5)An interdisciplinary research model to investigate psychosocial cofactors in disease: Application to HIV-1 pathogenesis, By Margaret Kemeny. Brain, Behavior, and Immunity 17. 2003. p. S62-S72.

6)Psychoneuroimmunology and health psychology: An integrative model, By Erin Castanzo and Susan Lutgendorf. Brain, Behavior and Immunity 17. 2003. p. 225-232.

7) The Mind-Body Interaction in Disease. By Esther Sternberg and Philip Gold. Scientific American. 2002.

8) HEALTH PSYCHOLOGY: Mapping Biobehavioral Contibutions to Health and Illness. By Andrew Baum and Donna Posluszny. Annual Reviews. Psychology. 1999. 50:137-163.


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