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"You Thought it Was All in Your Head" How the field of psychoneuroimmunology is changing the way we view our bodies and our lives By Sarah Tewhey Psychology The study of mental and behavioral processes in humans and other animals. Psychology examines the nature and functions of the mind and the way that mental processes are affected by environment, situations, relationships, physical state, and mental state. Neurology The scientific study of the anatomy, physiology and pathology of the nervous system. This system consists of the brain, spinal cord, peripheral nerves, neuromodulators and muscles. Immunology The study of the body's natural defense system against disease and infection. The immune system consists of various immune organs such as the spleen, the lymphatic channels and the various immune cells that circulate in the blood and throughout the body. Endocrinology The study of the anatomy and physiology of the endocrine glands and the hormones that they produce. Psychoneuroimmunology This emerging field bridges and integrates the relationship between the mind, the nervous system, the endocrine system and the immune system, bringing new insight into the way that human physiology relates to our daily lives, our environment and the processes of disease and healing Psychoneuroimmunology has proven that neural pathways and chemical messengers connect these body systems in an functionally integrated network throughout the entire body (Pert, 1997). This network allows the mind and body to communicate with and influence one another on a moment to moment basis. Traditional healers and the general public have long understood the connection between the body and the mind. The scientific community has now begun to produce the evidence that this integration exists within our physiology. While many scientists over the past century have studied the possibility that these systems and the mind may be communicating, it was only in the 1970's and 1980's that their research began to be taken seriously. Psychoneuroimmunology as a terms was used first in 1974 by Dr. Robert Ader (Wachterman, 2002) and since then has slowly gained acceptance as a legitimate and worthy branch of science. Psychoneuroimmunology is on the cusp of understanding how human beings function and maintain health in changing situations. But how does it work? Why is it important? And how can it shape the way we live? The Physiological Pathways of Psychoneuroimmunology The best understood and most widely researched area of PNI is the stress response and its relationship to the immune system. This relationship is a valuable key to understanding how we stay healthy and what makes us susceptible to illness and disease. The human response to stress follows a path from the brain to the adrenal glands located above the kidneys. The hypothalamus receives sensory information from centers in the brain that process both logic and emotion, as well as from the nervous system. If relayed messages of a potentially stressful situation, the hypothalamus releases corticotrophin releasing hormone (CRH) into the anterior pituitary. The pituitary releases another hormone known as adrenocorticotropic hormone (ACTH) which triggers a response in the adrenal cortex to release corticosteroids. One of these corticosteroids, known as cortisol has the ability to act on many organs systems and cells throughout the body to create physiological changes. Cortisol also sends a signal back to the hypothalamus in order to stop the flow of hormones and inhibit the stress response (Marieb, 2001). Without this feedback loop to the brain via cortisol, the stress response continues indefinitely. As part of thr stress response the sympathetic nervous system also stimulates the adrenal medulla. This pathway is the fight or flight response and culminates in the release of epinepherine and norepinepherine. All of these chemicals create the wellknown characteristics that we recognize as the stress response (Marieb, 2001). This entire cascade is known as the hypothalamicpituitaryadrenal axis and is the process in action when we are cut off abruptly in traffic, frightened by a loud noise or subjected to work related stress. As individuals we know the feeling of this reaction through the increased heartbeat, ³butterflies² in the stomach, anxiety and ³rush² that it entails. During the hormone cascade of the HPA axis the chemicals to stimulate the reactions travel halfway down the body, from the brain all the way to the adrenal glands. Within three minutes stress hormones can be found throughout the entire body (Sternberg, 2001). This process of longdistance chemical transport and signaling is not unique to the HPA axis, but is a feature of many processes in psychoneuroimmunology. The immune system is closely connected to the stress response and this integration helps to explain why we are often more prone to illness when we are under significant amounts of prolonged stress (Sternberg, 2001). First, lets learn a little bit more about this system that supports our health. The Immune System Immune function is largely nonlocalized and made up of many different types of cells known as lymphocytes. These cells travel throughout the body via the blood and lymph. The numerous cells of the immune system circulate looking for foreign or "nonself" particles such as bacteria, chemicals and viruses that are a potential threat. Through a variety of different cells with highly specific functions the immune system surveys the body, identifies foreign particles and destroys them. In addition to these circulating cells, the immune system also has several localized structures such as the bone marrow, spleen, lymph, lymph nodes and thymus that support the circulating cells (Marieb 2001). In order for this system to provide protection and health it must be functioning optimally. An immune system that is overactive can result in the entire system mistaking self particles for foreign invaders. This gives rise to the class of diseases known as autoimmune disorders. On the other hand, an immune system that is deficient leaves the body open to and weak against infection and illness (Solomon, 1990). The Stress Immunity Connection There is an interesting relationship between the function of the immune system and the HPA axis. There is an understanding among the general pubic that situations of high, prolonged stress and emotional upheaval often can result in illness. Now, researchers have been able to show exactly why this is so. Short bursts of stress can actually be beneficial to the body and are necessary for survival. Brief periods of intermittent stress heightens the senses, increases performance and may actually boost immune function. The immune system takes hours or even days to stage a full response within the body. Therefore, the effects of a few minutes, or even several hours of the quickacting stress response is unlikely to effect the immune system. However, if the stress is prolonged it can create a situation that is harmful and debilitating. (Sternberg, 2001) Our bodies naturally have a lowlevel circadian HPA rhythm. When a stressful situation arises and jostles this pattern, the sympathetic nervous system interrupts the inhibitory action of cortisol on the hypothalamus (Marieb, 2001). Chronic stress means that the feedback loop to the hypothalamus is greatly reduced over a long period of time. The chemicals and hormones associated with the stress response continue to flood the body with no signal to stop. Cortisol also acts on immune cells to inhibit their reaction to foreign cells. If cortisol is constantly flowing throughout the body, then immune cells never have an opportunity to perform their proper functions, and newly born immune cells never have a chance to mature (Sternberg, 2001). The result is a severely depleted immune system and the onset of illness or infection when faced with foreign substances that enter the body. Hans Selye who coined the term "stress" in the middle of the twentienth century found that rats subjected to prolonged stress showed atrophy to the thymus, a structure that is instrumental in the production of Tcells. Unfortunately, the function of the thymus was unknown at this time and Selye did not fully understand the implication of his findings (Power, 2000). This is the actual physiology behind stress response and immunity, but what does this mean for our day to day lives? Studies have shown a variety of interesting results regarding the ways that mental state, life events and environment effect stress response, immune function and general well being. Some of the most conclusive studies have been conducted on family members of Alzheimer's patients who are primary care givers. These individuals are studied because they are generally under immense amounts of chronic stress. Studies have shown that these individuals suffer from immunosuppression and that the effects of the chronic stress on the immune system often remain for months after the family member dies or the situation changes (Cohen, 2002). In a different research study, Immunoglobulin E, the antibody that is responsible for allergic reactions as been shown to increase as a result of the stress response (Solomon, 1990). This physiological reaction makes logical sense for overall health and survival, as the body under stress must prepare for a variety of possible scenarios. The implications for this finding are interesting as they may in the future show a connection between chronic anxiety and allergies. Another popular research group are medical students around the times of major exams. In repeated experiments it has been shown in the days leading up to exams that the immune function of medical students will drop dramatically in response to stress, only to bounce back again after the exam as passed (KiecoltGlaser et all, 1984). This example is interesting as it shows that pure psychological stress without any threat of the physical harm that the fightorflight response is designed for is a very real phenomenon with actual physiological implications. The Body as an Information Network Until recently it was thought that the immune system operated independently and was relatively isolated from the other systems of the body (Solomon, 1990). Judging from the previous examples, this is clearly not the case. It is now understood that the cells of the immune system contain receptors for hormones and are in constant communication with the endocrine system (Pert, 1986). In addition, the nervous system plays a role in the regulation of the immune system. The structures of the immune system are innervated with large amounts of nervous tissue. The immune system also has the ability to talk back to the nervous system via substances called cytokines which are released by the cells of the immune system and travel to the brain directly. This creates a highly intelligent and completely bidirectional system in which information can be exchanged and regulation is an integrated process (Ader, Cohen & Felton, 1995). The connection between immune function and the nervous system is a sensible survival mechanism for the human body. As George Solomon (1990) states It would make sense for the two systems, nervous and immune to be linked. Both are concerned with adapting to and defending against the environment and relate the organism to the outside world....Two adaptivedefense systems that respond to the environment ought to talk to each other, as actually appears to be the case (p.176). There is a growing amount of evidence that Solomon is correct and that these two systems, along with the stress response are vitally linked for our survival and wellbeing. Receptors and the Chemical Messengers Attached to the surface wall of every living cell are tiny molecules known as receptors. They float along the outside of the cell wall with "roots" that can stretch deep within the interior. Each cell can have millions of various receptors on its surface and the receptors act as a sensory system for the cells that they inhabit (Pert, 1997) Receptors assess the environment around a cell and pick up chemical "messengers" known as ligands that are present in the interstitial fluid. Each receptor is build to bind to a specific messenger, and when the proper chemical comes along it will fit into the receptor the same way that a key fits into a lock. When this binding is successful the information contained in the ligand is able to enter the cell via the receptor, creating a series of chemical reactions within the cell. Depending on the molecular make up of the ligand it can bring a variety of messages to the cell that alter the cell's function (Pert, 1997). Ligands have extremely specific messages and are divided into a variety of different groups. Both the chemical signals of the nervous system and the endocrine system act as ligands. In the nervous system the ligand group known as the neurotransmitters are small molecules that are used to carry information from neuron to neuron throughout the nervous system to various parts of the body. Over fifty neurotransmitters have so far been discovered and include substances such as acetylcholine which stimulates the skeletal muscles, histamine and dopamine. They have been described as the "language of the nervous system" (Marieb, 2001). The ligands of the endocrine system are hormones that are excreted by endocrine glands and travel throughout the body with the general function of regulating metabolic processes within the cells. Hormones also alter the activities of a cell, usually either increasing or decreasing certain processes. Examples of hormones include the ones previously mentioned that are involved with the stress response, insulin, thyroid hormone and melatonin which controls our patterns of wakefulness and sleep (Marieb, 2001) "In short, the life of the cell, what it is up to at any moment, is determined by which receptors are on its surface, and whether those receptors are occupied by ligands or not." Candace Pert (1997 p. 24) What this amounts to is that we as humans are composed of a kind of chemical messenger soup that is changing with each passing moment. While the body was once perceived to be a hierarchal mechanism largely controlled by the brain, it is now becoming clear that the body instead functions as an ever changing network of information with open lines of communication between all systems of the body, the brain and the processes of the mind (Pert, 1986). Mood, Mind and the Chemical Messengers Many of the chemicals released by the endocrine, immune and nervous systems travel throughout the body and seem to play a role in mood regulation. Hormones released by the adrenal cortex such as cortisol can induce anxiety and nervousness (Marieb, 2001). Cytokines secreted by the immune system can effect sleep and appetite and are the substances that make us feel depressed and lethargic when we are ill (Sternberg, 2001). Neurotransmitters released by the nervous system such as serotonin can produce feelings of relaxation (Wurtman, 1986). There is one group of ligands that we have not yet discussed that may effect mood more than the others. These are the neuropeptides. Neuropeptides are short strings of amino acids that comprise the majority of the ligands and regulate nearly all of the processes that keep us alive. These small proteins are released from nerve cells, and like the chemicals of the HPA axis can create reactions in distant parts of the body. The neuropeptide group contains substances such as the family of endorphin molecules that mediate pain perception and give the feeling of runner's high after intense exercise. The endorphin family also contains the peptide that is the body's natural opiate (Marieb, 2001). This opiate peptide appears to also be responsible for human bliss and bonding (Pert, 1997). Neuropeptides are considered to be the body's natural answer to psychoactive drugs, pain killers and other substances. When looked at as a group they truly appear to be a sort of endogenous pharmacy. In an example of how the lines between body systems are truly being blurred, neuropeptides also sometimes double as hormones. Insulin, generally thought of as a hormone that is created by and used within the pancreas to regulate blood sugar has now been found to be produced within the brain and can behave as a neuropeptide (Pert, 1986). Dr. Candace Pert, a pioneer in the field of neuroscience and psychoneuroimmunology suggests that these neuropeptides are actually the biochemical basis of emotion. She asserts that the presence of particular emotions may stimulate certain peptides, thereby altering the chemical balance of the entire body. To complete the cycle, this chemical balance of the peptides may help to evoke a particular mood or emotional state (Pert, 1997). This process occurs with fluidity over the course of our lives. Neuropeptides create what Candace Pert calls "altered states of consciousness" (Pert, 1997). While we may think of this as a dramatic shift in perception, these altered states are far more subtle and intrinsic to daily life. An excellent example is the case of angiotensin. This hormone is created in the liver and has long been known to mediate thirst (Marieb, 2001). However, this hormone also acts as a neuropeptide. Concentrations of receptor sites for angiotensin can be found in the amygdala, an area of the brain that processes fear. In rats, if the portion of the amygdala that is rich in angiotensin receptors is stimulated with a drop of this substance, then the rats will begin to drink, even if they are already sated with water (Pert, 1986). It is this type of "altered state", the desire for water, even if one is not thirsty that suggests that neuropeptides may have a connection to the way that humans experience their internal environment and emotions. When mapping for neuropeptides throughout the brain an extremely high concentration of receptors are found in the various structures of the limbic system, an area associated with emotion (Marieb, 2001). The limbic system is not the only place that neuropeptide receptors are found. High concentrations are also found in areas of nerve ganglion that are responsible for the entry of information from each of the senses into the nervous system. Neuropeptides and neuropeptide receptors have also been found in high concentrations in the gut, giving way to speculations about why humans claim to have "gut feelings" (Pert, 1997). Neuropeptides and the immune system also share an important link in our physiology. Within the immune system are cells called monocytes. These cells travel through the blood stream and ingest harmful foreign substance. They are also involved in tissue repair after there is a trauma to the body. Remarkably, receptors for every single neuropeptide recognized so far, have been found on monocyte cell walls. Through a process called chemotaxis, monocytes as they float through the blood are attracted to nearby neuropeptides (Pert, 1986). The monocytes navigate their way through our bodies by picking up the signals of these small proteins that have a close connection with our state of consciousness. Psychoneuroimmunology is a true body wide system of communication that utilizes the the brain, the nervous system, the endocrine glands and the immune system. It appears that the neuropeptides act as messengers, traveling throughout the body to keep these systems in harmonious communication. In the words of Candace Pert, We are all aware of the bias built into the Western idea that consciousness is totally in the head. I believe....that we need to start thinking about how consciousness can be projected into various parts of the body (1986, p.154). Implications for Mind/Body Therapies The field of psychoneuroimmunology is new and its true implications in health care and its effectiveness as a new model with which to develop therapeutics is still being studied. Evidence has still not been produced that established illness can be healed by lowering the stress response. And, drugs created to mock viruses such as AIDS that attach themselves to neuropeptide receptors have still not made their way through clinical trials (Pert, 1997). It is clear however, to individuals in the field of mind/body medicine that the current research may lead to new understandings regarding CAM therapies. Some studies into the biological mechanisms for CAM therapies are already underway, bringing increasing credibility to these types of treatments. Slowly, over time PNI may begin to uncover the mechanisms behind many ancient healing modalities. Acupuncture Acupuncture may date back as far as 4500 years ago and is an instrumental treatment in traditional Chinese medicine (Mayer, 1998) . This treatment, used most widely for nausea and pain here in the United States is being closely studied. Thus far, there may be an explanation for the effectiveness of acupuncture in the context of pain relief. Within a research group, pain was stimulated and an acupuncture treatment was admisnistered. The group showed relief to the stimulated pain because of the treatment. Naloxone was then given to the group. Naloxone is a substance that is known to bind to the opiate receptor, but does not convey the same pain relieving properties as our own endogenous opiates. Naloxone also has the ability to act as an antagonist and "bump" our endogenous opiate neuropeptides off of opiate receptors after they have bound. (Mayer, 1998). Because pain relief given by the acupuncture treatment was negated by the presence of naloxone, this study shows that bound opiates were the molecules responsible for the pain relief and that acupuncture has the ability to stimulate the release of these molecules. Keeping in mind that every neuropeptide receptor has been discovered among the monocytes of the immune system the following research shows that the physiological implications of acupuncture may extend beyond the area of pain relief. Voluntary Respiratory Control Breath control is perhaps one of the oldest mind/body mechanisms known to humankind. In the yogic tradition it was developed into an elaborate series of techniques known as pranayama. Voluntary changes in breathing patterns have been shown to create distinct changes in the autonomic nervous system. This system regulates body functions that humans typically do not have much control over such as heart rate and digestion (Marieb, 2001). In numerous studies voluntarily slowing the rate of respiration has reduced the stimulation of the autonomic nervous system with measurable differences in pulse rate, skin resistance and "selfreported anxiety" (Sovik, 1998) The autonomic nervous system and the stress response go hand in hand and it appears that voluntary respiratory control creates a reduction in the signs of stress. Given what has been presented about the long term effects of stress on the immune system it is possible that engaging in controlled breathing practices may boost immunity and possibly even alter the chemical balance of the brain and body. Faith and Spirituality Faith and contact with spirits, gods and other dimensions have been a prominent and important part of traditional medicine. Strong research is emerging that spiritual faith plays an important role in healing and that humans may be "hardwired" (Koenig, 2002) for spiritual faith as a survival mechanism. Religious belief has been shown to correlate with reduced stress and anxiety, to promote hope and an optimistic outlook and foster greater social support, especially among women and AfricanAmericans (Koenig, 2002). While these areas are relatively subjective, there is data that correlates these specific factors with a positive physiological response. In a study conducted in 1999 among HIV positive gay men significantly higher CD4+ Tcell counts were found among men who participated in religious activities such as prayer, spiritual discussion and service attendance. In transcendental meditation practitioners researchers found a decrease in circulating stress hormones and among women awaiting biopsies for breast cancer, levels of cortisol were found to be lower among those who used prayer and faith as a coping mechanism (Koenig, 2002). It is still speculative at this point, but the overall better health of these individuals can probably be attributed to the reduction in stress, the positive outlook and the social support that spiritual faith provides. Its Not All in Your Head What were once considered to be separate systems are now being integrated as a functional network of information that has connections to every system of the body. "Our consciousness effects our physical bodies. It is life affecting the flow of a river by placing rocks in the stream. These rocks are our thoughts. They represent our true intent. Brain researchers estimate a person thinks some 60,000 thoughts a day. This is like putting 60,000 rocks a day into our river to make it flow the way we choose. Nintyfive percent of these thoughts are the same we had as yesterday. We use alot of energy day after day picking up these rocks and returning them to the same place. Thoughts are like the directors in the creation of the molecules of your body. Think back to a few years ago. Your body replaces many of its cells every year. The body you had a few years ago no longer exists. Your body recreates itself using...thoughts, beliefs attitudes and emotions." Carl Brahe (1992, p.xii) Our bodies are not static, not impermeable and are influenced by the thousands of stimuli, both internal and external that we encounter each day. Through our relationship to environment, to others and to ourselves we not only shape our minds, but our physiology as well. How we choose to interpret and react to our lives not only effects our happiness and peace of mind, but also the billions of tiny immune cells, hormones and neuromodulators that regulate the internal landscape of our bodies. Bibliography Ader R., Cohen N. & Felten D.L. (1995). Psychoneuroimmunology: interactions between the nervous system and the immune system. Lancet, 345, 99-103. Brahe, C. (1992). Healing on the edge of now. Hygiene, Colorado: SunShine Press. Cohen, S (2002). Psychosocial stress, social networks and susceptibility to infection. In H.G. Koenig & H.J. Cohen (Eds.), The link between religion and health: Psychoneuroimmunology and the faith factor (pp. 101-123). New York: Oxford University Press. Kiecolt-Glaser JK, Garner W, Speicher C, Penn C, Holliday J & Glaser R. (1984). Psychosocial modifiers of immunocompetence in medical students. Psychosomatic Medicine, 46, 7-14. Koenig, H.G. (2002). The connection between psychoneuroimmunology and religion. In H.G. Koenig & H.J. Cohen (Eds.), The link between religion and health: Psychoneuroimmunology and the faith factor (pp. 11-30). New York: Oxford University Press. Marieb, E.N. (2001). Human anatomy and physiology (5th ed.). San Francisco: Benjamin Cummings. Mayer, D.J. (2000). Biological mechanisms of acupuncture. In E.A. Mayer & C.B. Saper (Eds.) Progress in brain research, Vol 122 (pp. 457-478). Amsterdam: Elsevier Science B.V. Pert, C. (1997). Molecules of emotion. New York: Simon &Schuster. Pert, C. (1986). The wisdom of the receptors: Neuropeptides, the emotions and body-mind. Advances, 3(3), 8-16. Power, J. (2000). Psychoneuroimmunology. Retrieved May 9, 2004 from http://www.dreamingearth.com/psychoneuroimmunology.html Solomon, G (1990). Emotions, stress and immunity. In R. Ornstein & C. Swencionis (Eds.), The healing brain: A scientific reader (pp.174-181). New York: The Guilford Press. Sovik, R. (2000). The science of breathing - the yogic view. In E.A. Mayer & C.B. Saper (Eds.) Progress in brain research, Vol 122 (pp. 491-506). Amsterdam: Elsevier Science B.V. Sternberg, E. (2001). The balance within: The science connecting health and emotions. New York: W.H. Freeman and Company. Wachterman, M. (2000). Psychoneuroimmunology: Bi-directional interactions between the brain and nervous system. Retrieved May 13, 2004 from http://serendip.brynmawr.edu/bb/neuro/neuro00/web1/Wachterman.html copyright 2003 ____________________________________________________________ Sarah Tewhey is a student and teacher of Yoga, Ayurveda and the healing arts. She completed two years of study with Dr. Vasant Lad at The Ayurvedic Institute and a B.S. at Lesley University in Mind/Body Studies with a specialization in the female healing process and its relationship to modern medicine. Sarah is currently a student in the Masters program at Southwest Acupuncture College in Albuquerque. Sarah can be contacted at: sarah@ayurlight.com |
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