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Happiness and the Immune System

by Dr Shara BA Cohen(more info)

listed in mind matters, originally published in issue 82 - November 2002


I remember when I used to travel to school I would practice my smile, trying to get it just right so that I didn't look false or silly. My parents told me that people would like you if you smile as it makes them feel good. But it made me feel good too, and enabled me to have a positive outlook through my school years. What I didn't realize was that I was empowering my immune system.

For over 20 years there has been scientific documentation suggesting that a positive outlook keeps your body healthy, whereas stress, anxiety, depression and bereavement have all been linked to serious diseases including cardiovascular disease, osteoporosis, arthritis, diabetes, certain cancers, Alzheimer's disease, periodontal disease and irritable bowel syndrome, to name a few.

Figure 1. Normal immune response against virus infection
Figure 1. Normal immune response against virus infection

The Brain and the Body

The major reason for these links between a person's mood and their illness is the strong relationship between the brain and the immune system. The classical stress hormones (for example cortisol) are released by the adrenal gland and controlled by the hypothalamus-pituitary-adrenal axis (HPA). Primate studies have demonstrated persistent alterations in the functioning of this HPA axis in animals reared by mothers living in moderately stressful conditions.[1] In addition, stress hormones controlled by the HPA have been shown to have direct modulatory effects on different immunological parameters. For example, in a recent study, 16 healthy human volunteers were randomly placed into two groups to receive either a stress hormone or a saline infusion for six hours.[2] Blood samples were taken before and after infusions and the effect of the stress hormones was assessed on the T cell populations. The stress hormone infusion produced a decrease in the percentage of both T helper and T cytotoxic cells. This suggests that it is modulation of the HPA that controls the balance between the brain and the immune system. It is therefore not surprising that there is documented evidence of a reduction of T cell function in the bereaved, people with post-traumatic stress and people with anxiety. This would lead to a reduced ability of these groups to fight infection and disease.

The Effect That Your Mood Has on the Immune System Can be Fatal

Most of us have heard stories regarding an elderly person who has died or fallen seriously ill within months of the death of a lifelong partner. These instances are no longer looked on with scepticism, as there are real scientific explanations for people dying from a 'broken heart'. Bereavement, depression, stress and anxiety can all reduce the numbers of immune cells which help you to fight against infection (See Figure 1 above).

Negative emotions will therefore contribute to prolonged infection, which could be fatal in the elderly or people with chronic infection. This has been particularly highlighted with people who are sero-positive with HIV. Several studies have shown that higher depressed moods in HIV patients are significantly associated with fewer CD[4] (helper/inducer) T lymphocytes and these that these patients consistently demonstrate immunological patterns consistent with HIV activity and progression.[3]

As with all science, however, it is not that simple. In diseases where the immune system is the cause of the disease, the HPA is altered.[4] In these cases negative emotions have been shown to enhance the number of and further activate the cells that are perpetuating the illness. This enhancement of the immune system is correlated with deterioration in symptoms. To illustrate are two examples of autoimmune diseases, 1) type 1 diabetes - where the body's immune system attacks the pancreas and 2) rheumatoid arthritis - where the immune system attacks the synovial membrane within the joint. In both these diseases negative outlooks influence the course of disease.

Diabetic Example

A study has shown that diabetics who have experienced the recent death of a loved one can show a marked increase in T helper cells, in contrast to diabetics who had not experienced a recent death, after both groups viewed a film about a happy, but doomed, love affair. This increase in T helper cells would augment the immune attack on the insulin-producing cells in the pancreas, perpetuating the diabetes.[5]

Rheumatoid Arthritis Example

Researchers in New York have shown that rheumatoid arthritis patients who perceived punishing responses (e.g. getting irritated or angry when the patient is in pain) from close others displayed increased negative emotions over time and were rated (independently) by their rheumatologist as having a more severe disease.[6]

With Cancer it is Different

The situation gets even more complicated when we look at cancer. It is well known that natural killer (NK) cells help the body fight against cancer development. NK cells recognise altered body cells, such as cells infected with virus or cancer cells, and they act as the body's first line of defence. They have a critical role in tumour immuno-surveillance, as they roam the body searching for cells that look slightly different from the norm and kill them. Thus, NK cells have been considered to be the major component of anti-tumour immunity, responsible for rapid elimination of malignant cells from the blood. However, stress hormones and negative moods have been shown to increase the levels of NK cells in our bodies.

So can stress, anxiety, bereavement and other negative emotions be good for cancer patients because of the rise in NK cells? The simple answer is no! Firstly, this increase in NK cell numbers is not observed in the long term and it has been suggested that this transient phenomenon occurs prior to the downregulation of immune function, reflecting the body's defence to a stressor.[7] Secondly, these NK cells have increased in number only and are not activated i.e. they are not ready to kill (Table 1). In cancer it is more important to have cells that are ready to kill than to have large numbers of cells waiting to become activated. To become activated the NK cell needs to receive the immune systems hormones (cytokines) from T cells (which are reduced in number with negative emotions). Thus, it has been shown that NK cell activity is reduced in cancer patients when the patient is anxious about the cancer, whereas encouragement of the expression of feelings (especially anger), in cancer patients is associated with a longer survival of the patient.[8]

What can we do?

It is easy to say relax, be happy and then everything will be OK. Obviously this is naive, but there are scientific studies that show that, just by staying relaxed and having meaningful relationships you can boost your immune response. Below I have highlighted six of the ways we can enhance a positive outlook and their effect on the immune system:

1. Inducing a relaxed state, for example, by hypnosis can prevent the decline in T cells induced by stress.[9],[10] Hypnosis has shown to have a positive effect on allergy management, alleviate dermatological disorders such as psoriasis and decrease progression of HIV.

2. Maintaining close personal relationships that diminish negative emotions can enhance health, in part through their positive impact on the immune system. For example, a happy functional marriage has been shown to be consequential for good health, whereas negative dimensions of marital functioning directly influence cardiovascular, endocrine, immune, neurosensory, and other physiological mechanisms in a negative manner.[11]

3. Simply holding a person's hand can reduce stress hormone levels in times of anxiety. This has been clearly shown by studies of patients undergoing cataract surgery under local anaesthesia, who had reduced levels of stress hormones in their circulation due to handholding/massage either before or during surgery.[12],[13]

4. Music. Listening to music in a relaxed state can increase well being and relaxation and reduce tension during the listening experience. It can also decrease the levels of the stress hormone cortisol.[14]

Making music, for example playing an instrument or singing can reduce anxiety and tension. The beneficial effects are further enhanced if the music making is within a group. Even group drumming will increased NK cell activity.[15] Choral singing can make the participant feel more positive, more alert and spiritually uplifted. It may also improve lung function and breathing, mood and reduce stress.[16]

5. Having a massage significant decreases anxiety and increases relaxation. Stress hormones, NK cell function and cytotoxic T cell function are also increased.[17]

6. Emphasizing emotional expression results in smaller stress-induced changes in NK cells and has shown survival benefits in breast cancer and melanoma patients.[18]

In addition, optimism in the absence of academic-social conflict can increase the number of circulating T cells[19], exercise can improve the mood[20], and humour and an ability to laugh reduces stress, enhances hope, relieves tension, and stimulates the immune system.

Psychosomatic Health

It seems obvious from the discussion above that a positive frame of mind can help the body fight ongoing diseases such as cancer, HIV infection, diabetes and so on. But your state of mind is also important when you are healthy. By maintaining a positive state of mind you can keep these diseases at bay. Your stress hormone levels are minimal and your immune system becomes primed for action, your NK cells maintain a level of activation ready to kill any altered cells such as cancer or virally infected cells and your T cells are at an optimal concentration to fight disease.

In a normal individual there is also a balance of the immune system's hormones (cytokines). These cytokines act in a feedback mechanism, maintaining the right concentration and level of activation of immune cells in the body. A shift in cytokine concentration can therefore alter the immune status. The concentration of cytokines is also effected by emotion (Table 2). Thus, a healthy individual with negative emotions could have an increase in anti-inflammatory cytokines and/or a decrease in the pro-inflammatory cytokines. This would inhibit a normal immune response to virus infection by T cells and tumour surveillance by NK cells.

To Conclude

Negative emotions can intensify a variety of health threats and distress-related immune dysregulation may be a core mechanism behind a large and diverse set of health risks associated with negative emotions. Conversely, staying calm, being optimistic, expressing your feelings and having close personal relationships are all good ways to boost your immune system and help you to maintain your health.

Don't worry, be happy, stay healthy.


1. Marshall RD and Garakani A. Psychobiology of the acute stress response and its relationship to the psychobiology of post-traumatic stress disorder. Psychiatr Clin North Am. 25(2): 385-395. 2002.
2. Januszkiewicz A, Essen P et al. A combined stress hormone infusion decreases in vivo protein synthesis in human T lymphocytes in healthy volunteers. Metabolism: Clinical and Experimental. 50(11): 1308-14. 2001.
3. Kemeny ME, Weiner H et al. Repeated bereavement, depressed mood, and immune parameters in HIV seropositive and seronegative gay men. Health Psychology. 13(1): 14-24. 1994.
4. Mukai E, Nagashima M. et al. Comparative study of symptoms and neuroendocrine-immune network mediator levels between rheumatoid arthritis patients and healthy subjects. Clinical and Experimental Rheumatology. 18(5): 585-90. 2000.
5. McClelland DC, Patel V et al. The role of affiliative loss in the recruitment of helper cells among insulin-dependent diabetics. Behavioral Medicine. 17(21): 5-14. 1991.
6. Griffin KW, Friend R et al. Distress and disease status among patients with rheumatoid arthritis: roles of coping styles and perceived responses from support providers. Ann Behav Med. 23(2): 133-8. 2001.
7. Koh KB. Emotion and immunity. Journal of Psychosomatic Research. 45(2): 107-15. 1998.
8. Magarey, CJ. Aspects of the psychological management of breast cancer. The Medical Journal of Australia. 148(5): 239-42. 1998.
9. Gruzelier J, Smith F et al. Cellular and humoral immunity, mood and exam stress: the influences of self-hypnosis and personality predictors. International Journal of Psychophysiology. 42(1): 55-71. 2001.
10. Kiecolt-Glaser JK, Marucha PT et al. Hypnosis as a modulator of cellular immune dysregulation during acute stress. Journal of Consulting and Clinical Psychology. 69(4): 674-82. 2001.
11. Kiecolt-Glaser JK and Newton TL. Marriage and health: his and hers. Psychological Bulletin. 127(4): 472-503. 2001.
12. Moon JS and Cho KS. The effects of handholding on anxiety in cataract surgery patients under local anaesthesia. Journal of Advanced Nursing. 37(3): 407-15. 2001.
13. Kim MS, Cho KS et al. Effects of hand massage on anxiety in cataract surgery using local anesthesia. Journal of Cataract and Refractive Surgery. 23(6): 884-90. 2001.
14. Burns SJ, Harbuz MS et al. A pilot study into the therapeutic effects of music therapy at a cancer help center. Alternative Therapies in Health and Medicine. 7(1): 48-56. 2001.
15. Bittman BB, Berk LS et al. Composite effects of group drumming music therapy on modulation of neuroendocrine-immune parameters in normal subjects. Alternative Therapies in Health and Medicine. 7(1): 38-47. 2001.
16. Clift SM. Hancox G. The perceived benefits of singing: findings from preliminary surveys of a university college choral society. Journal of the Royal Society of Health. 121(4): 248-56. 2001.
17. Ironson G, Field T et al. Massage therapy is associated with enhancement of the immune system's cytotoxic capacity. Int J Neurosci. 84(1-4): 205-17. 1996.
18. van der Pompe G, Antoni MH et al. An exploratory study into the effect of group psychotherapy on cardiovascular and immunoreactivity to acute stress in breast cancer patients. Psychother Psychosom. 70(6): 307-18. 2001.
19. Segerstrom SC. Optimism, goal conflict, and stressor-related immune change J Behav Med. 24(5): 441-67. 2001.
20. Starkie RL, Rolland J et al. Effect of adrenergic blockade on lymphocyte cytokine production at rest and during exercise. Am J Physiol Cell Physiol. 281(4): 1233-40. 2001.


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About Dr Shara BA Cohen

Dr Shara BA Cohen BSc (Hons) PhD CBiol FWIF FRCPath FIBMS FRSB started her working life as a research scientist and lecturer with over 100 peer-reviewed scientific publications. She followed a classical scientific career until she left mainstream science in 2000 (which coincided with the birth of her first daughter) to establish the Life Science Communications company, which she sold in 2016.  In 2013 she was diagnosed with Cancer and set up Cancer Care Parcel with information about dealing with cancer treatments. Dr Shara Cohen may be contacted on Tel: (+44) 020 7183 8231;

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