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Psychoneuroimmunology and Aromatherapy:
A Neuropsychologist's Perspective


Joie Power, Ph.D.

Psychoneuroimmunology is the branch of biomedical science that explores the relationships between the nervous system, emotions, and the endocrine and immune systems; it is concerned with the links between our states of mind and our states of health. It is one piece of a very complex puzzle - the puzzle of what creates and maintains health and well-being.

Allergies, colds and other types of infections, autoimmune diseases, and cancer are illnesses that all arise from immune system dysfunction. While virtually everyone catches occasional colds or has had an infection of some kind, people vary in how frequently they experience these problems and most never experience the more serious consequences of immune dysfunction, such as cancer. Since most people are faced with similar immune challenges, why do some stay healthy and some do not? Why do some people's immune systems seem to hum along while other people succumb to various types of illness? Of course this is a complicated question and the causes of illness are many and multi-factored. Genetics play a part, as do lifestyle choices, and even luck is a factor, but a very significant contributor to immune system function, and therefore to health, is your state of mind.

The profound role played by mental and emotional states in the creation of illness has long been recognized by healers and practitioners of traditional medicine. Thus, the Astangahradaya Sustrasthana, the classic Ayurvedic text complied around 600 A.D. states:

"....poor prognosis is given to those who are afflicted by intensely negative emotions; hatred, violence, grief, ingratitude, and other distorted expressions of raga (desire, passion) are much stronger than the body's ability to maintain balance. When the patient is unwilling or unable to abandon these passions they will create new diseases just as fast as the doctor can remove the old ones."

As ancient as our recognition of the mind/body connection is, it has been largely neglected in the development of modern medicine which, since the 17th century, has been ruled by Rene Descartes' "Doctrine of Dualism", which defines the mind and body as separate and unrelated things. The renewed interest in Western medicine in the mind/body connection and the discovery of its routes and mechanisms of operation, through the emerging field of psychoneuroimmunology (PNI), represents one of the most significant and promising medical advances of the last several decades and is paving the way for the introduction of holistic practices into mainstream medicine.

So what exactly is this mind/body connection? The basic premise of mind/body medicine is that our thoughts, moods, and feelings influence our bodies at the physical level and express themselves in our health and that the state of our physical body, in turns affects how we feel and can even play a role in creating our personality. The brain has often been called the organ of the mind. It is the source and executor of all that we think, feel and do and it is through the brain's structural and chemical connections with our other organs, glands, and tissues that feelings influence health and health influences feelings.

The Stress Response:

The "Stress Response", which is also called the "Fight or Flight Response" was first described by Hans Selye in the early 1970's and still offers one of the best illustrations of the mind/body connection. The Stress Response occurs when a person experiences something that they perceive to be threatening. When the Stress Response is activated, the brain stimulates the release of a cocktail of chemicals that prepare the body to fight or flee. As a result, the body experiences increases in blood pressure, respiratory rate, heart rate, blood flow to skeletal muscles and other physiological changes. These physiological changes aid the body in surviving an immediate threat by temporarily increasing strength, speed and aggressiveness and decreasing sensitivity to pain but they have also been shown to cause short term decreases in immune function.

The Stress Response has been with us throughout our evolutionary development but in earlier times it was self-limiting - it enabled us to save ourselves when a lion charged but then, because of built-in feedback loops, it shut off and neural firing and chemical activity returned to baseline levels. Today, the Stress Response has become a threat to health because it can be repeatedly provoked by routine events, like an angry boss or a hectic commute, and, for some, has become a chronic way of responding. For those who are chronically "stressed out", the nervous system is in a constant state of excitation and the Stress Response is experienced over and over again, causing the built-in feedback loops that should shut the system off to fail, resulting in weakened immune function. In time, the adrenal glands may become exhausted, leading to symptoms of weakness, dizziness, tiredness, headaches, memory problems, allergies, and more serious illnesses.

Effects of Stress on Health:

This type of chronic stress can have a profoundly damaging effect on the mind and body because a strong and balanced immune system is something that is absolutely necessary to the maintenance of health and vigor. It fights off infections that originate outside the body and diseases, such as cancer, that originate within the body, and it initiates and coordinates the healing process. A functional immune system is almost as vital to even your short-term survival as is a functional heart. If your heart stops beating you will be dead in about four to six minutes. If your immune system were to completely stop functioning all together, you would be dead within less than an hour or so because that's how quickly your body would be overwhelmed by the reproduction of unopposed bacteria and other pathogens.

In addition to waging this constant battle against outside pathogens, your immune system is also protecting you constantly from abnormal cells produced within your body through mutation, including malignant cancer cells, by destroying them before they can cause problems. However your immune system not only needs to be strong enough to do these jobs, it also needs to be balanced because an immune system that's too strong or active will attack things from inside or outside the body that it shouldn't, or will attack them too aggressively. So, for example, allergies are produce when your immune system over-responds to the presence of something from outside your body, like pollen, and autoimmune diseases, like Hashimoto's Thyroiditis, are produced when your immune system attacks normal, healthy cells.

In the last decade, the medical community has come to realize that mental states and personality patterns are linked to the development of many illnesses and to the recovery from even more. Research in the field of PNI has demonstrated, for example, that personality traits such as pessimism or emotional states such as depression raise the risk of developing many illnesses, including cancer, heart disease, hypertension, autoimmune disease, asthma, diabetes, and arthritis. Even mimicking negative emotions or watching a violent movie cause short-term reductions in the number and activity of various immune cells.

For those who doubt that personality can play a role in the development of disease, consider the phenomena, well known in psychiatry, in cases of multiple personality disorder (Dissociative Identity Disorder) where one "persona" will have a disease, such as diabetes, allergies, asthma, or hypertension, and other "personas", living in the same body, won't show any laboratory findings or symptoms of that disease.

How It All works:

The Stress Response, as mentioned above, is a survival mechanism which becomes maladaptive when it begins to be triggered repeatedly on a chronic basis. People vary in how effectively they cope with the routine stresses of life and not everyone experiences activation of the Stress Response on a frequent basis. Those who do, however, face a significant potential challenge to their heath and well-being because the Stress Response affects your nervous system, your endocrine system, your immune system and through these systems, your whole body. These effects operate through two major pathways: the Hypothalamic-pituitary-adrenocortical axis (HPA axis) and the Sympathetic Nervous System.

When the brain perceives a threat, it alerts the hypothalamus, a small collection of cells deep in the brain that is responsible for coordinating a great deal of the body's physiological activity. By secreting hormones that act on the pituitary gland, the hypothalamus is the key link between the brain and the endocrine system. Once alerted, the hypothalamus then does two things in sequence:

First, it sends signals directly to the adrenal glands through the nerves of the Sympathetic Nervous System. These signals stimulate the adrenal glands to release increased amounts of epinephrine and norepinephrine. The increase in these chemicals has several effects, including increases in heart rate, respiratory rate, muscle tone, and blood sugar levels; blood vessels in the skin and abdominal organs constrict and those in the brain dilate and the brain becomes more alert and efficient.

These physiological changes serve to mobilize your energy reserves, increase your mental and physical capabilities and strength, decrease your likelihood of bleeding from cuts on the body and wounds to the gut, and so on.

If the threat is something that's removed fairly quickly and is over and done with then this is as far as the process goes and your levels of epinephrine and norepinephrine return to normal. But if the stress or threat isn't fairly quickly removed then the hypothalamus begins to secrete corticotrophin releasing hormone (CRH) which travels through the blood stream to the pituitary gland which is, in turn, stimulated by it to release adrenocorticotropin hormone (ACTH). This ACTH then travels to the adrenal glands, where it causes those glands to release increased amounts of cortisol and other corticosteroids, which mobilize fat reserves, keep blood sugar levels high, inhibit allergic response, decrease inflammation, and decrease pain perception.

Just as is the case when epinephrine and norepinephrine are increased, these actions in the body are mobilizing you to fight or run and are also preparing to limit your risk of impairment or death if you're injured. For example, inflammation is a natural immune response that normally begins as soon as your body gets hurt but, if you are under threat, inflammation in the muscles and joints can slow you down and thereby get you killed- by releasing corticosteroids, which have the effect of damping down normal immune responses, the adrenal glands are helping to insure that you won't be hindered by an inflamed musculoskeletal system.

Feedback loops in the HPA axis normally insure that the function of the adrenal glands returns to normal and that cortisol and other stress hormone levels decrease once a threat is escaped. However, when a person begins to become "stressed out" on a chronic basis, the feedback loops begin to fail so that cortisol and related hormones are regularly staying too high. Then these physiological changes such as suppression of the immune system, increases in blood sugar levels, and elevated cholesterol can become chronic and you see increased rates of infection and the development of diseases like diabetes, arteriosclerosis, hypertension, and osteoporosis (chronically elevated cortisol causes bone demineralization). Eventual physical changes may occur in the tissues and organs of the body, such as atrophy of the thymus gland.

Although the classic model of the Stress response is based on what happens in the body when a threat is encountered, it's very important to understand that many things short of a real threat to life or safety may provoke the same chain of events through the sympathetic nervous system and the HPA, with resulting effects on endocrine function, immunity and health. As little as a week of inadequate sleep (75% of your "normal" sleep) will raise cortisol levels and therefore blood sugar levels and if this becomes chronic, diabetes can result. Common anxieties such as worry over money, fear of failure, stress in the home and so on create feelings of "being on edge" and lead to over-stimulation of the HPA.

Adrenal Fatigue/Exhaustion

If chronic stress is intense enough and goes on long enough, eventually the HPA axis gets too tired to keep producing enough epinephrine, norepinephrine, and cortisol and the levels of these chemicals goes from too high to too low and blood pressure and blood sugar levels which have been elevated may actually drop. Then, however, other problems appear. Because epinephrine and norepinephrine function as neurotransmitters, when they are elevated nerve pathways begin to become less sensitive to them and this is especially true in the hippocampus, an area of the brain that is involved in long-term memory storage. Memory impairment is often a symptom of chronic stress at stages where epinephrine/norepinephrine are high but when the HPA axis begins to "collapse" and the level of the neurotransmitters drops, then that memory impairment can worsen dramatically. In my years as a neuropsychologist, I have seen many cases of memory loss from chronic stress misdiagnosed as Alzheimer's disease and similar types of dementia.

Another serious consequence of adrenal fatigue involves the inflammatory and immune responses. Because circulating cortisol normally acts to suppress inflammation and to keep the immune system in check so that it doesn't become overactive, when the adrenals can no longer produce enough cortisol the way is opened for the development of autoimmune and inflammatory diseases such as arthritis, allergies, and Systemic Lupus Erythematosus. Because the immune system is complex, immune system dysfunction can eventually lead to manifestations of both immune and auto-immune illnesses at the same time, such as a person with Hashimoto's Disease who develops cancer.

Now for Some Good News

PNI has given us some bad news about the high stress lifestyles that so many of us live. At the same, however, it has brought some very good news. The good news is that the body knows and can re-establish a more adaptive way of responding. Shortly after Selye began talking about the Stress Response, Herbert Benson, a Harvard cardiologist, began reporting on the Relaxation Response. He identified this response while studying the physiological changes that occur in people practicing transcendental meditation. The Relaxation Response also involves communication between the brain and other body systems and is characterized by decreases in blood pressure, respiratory rate, heart rate, and muscle tension. The Relaxation Response is mediated by the Parasympathetic Nervous system: while the Sympathetic Nervous System, which was mentioned above, carries signals to the body to gear up for flight or fight, the Parasympathetic Nervous System carries signals to "rest and relax".

The Relaxation Response has been found to counter many of the negative physiological effects of stress and to enhance immune system function and the body's capacity for healing. Many activities and lifestyle changes have been shown to support the Relaxation Response and to have beneficial effects on health. These include progressive relaxation, mental imagery, breath work, proper diet and exercise, biofeedback, massage therapy, aromatherapy and many others.

Broader Implications

Studies in PNI have shown us that chronic stress and emotions like depression, anger and fear have adverse effects on our physical bodies. There is good reason to believe that negative attitudes in general have negative health repercussions and it seems likely that if we developed studies to examine the immune and general health effects of such negative attitudinal and spiritual states as bigotry, sexism, intolerance and hatred in all its forms we would find that holding these patterns in the heart and mind makes us sick.

Energetically, we may consider anything with a negative resonance to be a "pathogen" that invades the mind, body and spirit and provokes a defensive response within both the physical and subtle bodies. Up to a point, our innate defenses will fight these pathogens off but this fight weakens us if it is continual and eventually we become sick in body and exhausted in spirit.

So it's important to be aware of the energetic quality of the thought patterns that we hold, as well as of the physical environment around us. The culture that we live in is one in which we are all exposed to a continual flood of negative thought forms: violence, aggression, greed, materialism, terror, hatred. Many of us are also overwhelmed by other less obvious negative patterns in the form of attachments - to possessions, to power, to self-image and status. Just as you would not drink from a stagnant pool due to concerns of bacterial infection, be careful what you "drink up" from the world around you. Many thought forms are harmful to body, mind, and spirit; holding them in our consciousness drains us and squanders our energy.

Native American wisdom counsels us to "walk in beauty" and the whole deeper point of the findings from psychoneuroimmunology is that this isn't just pretty advice - it's a key to good health and long life.


Many studies have shown that some significant indicators of immune system function are affected by psychological factors such as mood and perceived levels of stress. Essential oils have been shown to have significant effects on mood states and these effects are believed to arise from stimulation of the olfactory nerve which sends signals into the limbic system, an area of the brain involved in the regulation of mood and emotions. Because the olfactory connections to the limbic system are very direct, inhaled odors can affect brain function, mood, and mental state almost instantly. In fact, an inhaled aroma affects the brain and its electrochemical signaling activity more quickly than an IV injection and one way in which essential oils may help to support healthy, balanced immune function is indirectly through the fairly rapid situational induction of the relaxation response and the reduction of anxiety and stress. Used consistently over time essential oils may promote lasting improvements in mood and reduction of stress levels, thereby aiding in the restoration of healthy immune system function.

Essential oils may also exert more direct effects on the immune system via their actions on the hypothalamus, the pituitary gland, the brain stem and other neural centers. The projections of the olfactory nerve are complex and one of the more interesting and relevant features of this system is that specific odors are routed to specific locations, depending on which olfactory receptors they bond with. Thus, one aroma may travel a specific pathway to the pituitary gland, where it triggers or inhibits the release of ACTH, while a different aroma may travel to a nucleus in the brain stem and stimulate the release of epinephrine. Though this phenomena has not been extensively studied with regard to essential oils, it supports the general idea that different essential oils may have different effects on both mood and immune system function.

In clinical practice, I have found aromatherapy to be a useful adjunctive intervention in cases of chronic stress and/or depression with resulting immune system weakness, fatigue, low vitality and other symptoms. To be fully effective when used in these conditions, aromatherapy must be integrated into a comprehensive treatment program that also includes proper diet and exercise, stress management, counseling, alternative treatments and appropriate medical supervision and treatment of on-going medical conditions when needed. The use of essential oils in massage is an especially effective method in such instances since massage also has a well established ability to reduce stress and promote relaxation. However, because alteration of hypothalamic and limbic system function by essential oils relies on nerve transmission pathways, and not on the transport of essential oil molecules through the blood, it is the inhalation of essential oil aromas that is the key to altering mood states, reducing stress, and supporting a balanced immune system. While massage does have the advantage of incorporating two modalities useful for stress reduction (touch and inhalation of essential oils), topical application is not a necessity and this is an area where good use can be made of diffusers and other devices, such as aromatherapy jewelry, that release essential oils into the air.

Essential Oils to Reduce Stress and Support the Immune System

There is a wealth of information on the use of specific essential oils for improving mood, reducing stress and addressing specific maladaptive emotional states. Some of those which I have found to work well include the following:

Essential Oils for Relaxation:
  • Lavender (Lavandula angustifolia)
  • Roman Chamomile (Chamaemelum nobile)
  • Clary Sage (Salvia sclerea)
  • Bergamot (Citrus aurantium ssp. bergamia)
  • Marjoram (Origanum marjorana)
  • Rose Otto (Rosa damascena)
  • Neroli (Citrus aurantium var. amara)
Essential Oils to Ease Fear/Anxiety:
  • Frankincense, Somalia (Boswellia carterii)*
  • Melissa (Melissa officinalis)
  • Patchouli (Pogostemon cablin)
  • Rose (Rosa damascena)
  • Lavender (Lavandula angustifolia)
  • Cedarwood (Cedrus atlantica)
  • Neroli (Citrus aurantium var. amara)
  • Spikenard (Nardostachys jatamansi)
  • Vetiver (Vetiveria zizanioides)
  • Valerian (Valeriana officinalis)
Essential Oils to Help Lift the Spirits:
  • Ylang Ylang (Cananga odorata var. genuine)
  • Bergamot (Citrus aurantium ssp .bergamia)
  • Geranium (Pelargonium graveolens)
  • Melissa (Melissa officinalis)
  • Sweet Orange (Citrus sinensis)
Essential Oils for Adrenal Support:
  • Geranium (Pelargonium graveolens)
  • Rosemary (Rosmarinus officinalis)
Nervines/Nervous System Tonics:
  • Frankincense (Boswellia carterii)
  • Roman Chamomile (Anthemis nobilis)
  • Clary Sage (Salvia sclarea)
  • Lavender (Lavandula angustifolia)
  • Palmarosa ( Cymbopogon martini)
  • Patchouli (Pogostemon Cablin)
  • Ylang Ylang (Cananga odorata)
Essential Oils That May Stimulate Immune Response:**
  • Tea Tree (Melaleuca alternifolia)
  • Cajeput (Melaleuca cajaputi)
  • Niaouli (Melaleuca viridiflora)
  • Bergamot (Citrus aurantium ssp. Bergamia)
  • Vetiver (Vetiveria zizanioides)
  • Lemon (Citrus limonum)

Essential oils may be used singly or as blends. I have had good results in some cases with the use of Melissa essential oil for controlling acute panic attacks when that oil is inhaled at the onset of an attack or just before and is used in conjunction with relaxation techniques or EFT (Emotional Freedom Technique). Lavender (Lavandula angustifolia) is another oil that can be used alone to help promote relaxation and relieve stress. This is the first essential oil that I discovered and used in practice and in the years when I was working in the operating room and performing cortical mapping procedures on patients who were awake during brain surgery I found that if I applied a single drop of lavender essential oil to my own arms before entering the operating room it helped to calm my patients' anxiety (as well as my own) during this long and stressful procedure. Frankincense is another oil that works well on its own to induce deep breathing and relaxation and I have found it to be a favorite among acupuncturists and dentists who are looking for something to reduce client anxiety since it can be diffused in the office without causing drowsiness.

It is chronic stress and chronic mood disturbances, however, rather than situational ones which eventually lead to on-going suppression or imbalance of immune function and to compromise of vitality and health. In these situations, the use of essential oil blends is generally more effective than single oils. By using two or more oils in a blend, several aspects of a problem can be addressed at one time and there are synergistic benefits that arise from the interactions among the oils. The oils can also be rotated over time to keep the blends fresh and interesting to the client, to address changing symptoms, and to avoid any potential problems which could arise from long-term use of particular oil. For example: lavender, bergamot, frankincense and ylang ylang blend well for use with someone who has prominent symptoms of depression and exhaustion as a part of the clinical picture. Frankincense is an essential oil that I use frequently with people who are exhausted and debilitated as I find it has an overall strengthening and fortifying effect on the mind/body/spirit. Other essential oils listed under the category of nervines/nervine tonics will also help to strengthen and restore the nervous system when it has been exhausted or thrown out of balance by chronic stress. Where chronic anxiety is a prominent feature and there is restlessness lavender, cedarwood, vetiver and neroli could be tried and, again, frankincense and other nervines could be of use for their calming and restorative properties. Effective blending is the true art of aromatherapy; there are no hard and fast rules and all of us who practice in this field have our own favorite combinations. In all instances, however, a blend must be aromatically pleasant to the person using it and must not contain aromas that the user associates with a bad experience.

*Note: Boswellia carterii is endangered in Oman

** Immune stimulating essential oils should generally be avoided in the presence of autoimmune disorders/diseases

This document is copyrighted and may not be copied, published or reprinted in any form without written permission of the author, Joie Power, Ph.D.

Copyright © 2010 Joie Power, Ph.D. / The Aromatherapy School  |  All Rights Reserved

Dr. Power is a retired board certified neuropsychologist and former Assistant Professor of Surgery/Neurosurgery at the Medical College of Georgia, where she performed intra-operative cortical mapping with renowned neurosurgeon Herman Flanigan, M.D. She has over 20 years of clinical experience in both in-patient and out-patient settings and during her years of practice has also been both a practitioner and student of alternative healing methods, including herbal medicine, aromatherapy, Reiki, Chinese Medicine, and other energetic healing systems. Her extensive formal training and experience in the olfactory and limbic systems of the brain give her a unique qualification for understanding the actions of essential oils in the body. Dr. Power, founder of one of the earliest essential oil companies in the U.S. to specialize in therapeutic quality essential oils, is now a clinical consultant for Artisan Aromatics as well as an internationally known writer and teacher in the fields of aromatherapy and alternative medicine. Her approach to aromatherapy weaves together her solid scientific training and strong clinical skills with a holistic philosophy that honors body, mind and spirit. Dr. Joie Power is also the author of The Quick Study Guide to Aromatherapy and numerous published articles on aromatherapy and related topics.

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