Emotions and the Immune System

Have you ever noticed that you usually get colds a few days after a setback or bad experience in your life? A recent experiment reported in the New England Journal of Medicine (Cohen '91) confirmed that this is no mere illusion. The researcher gave psychological stress questionnaires designed to measure helplessness and negative emotions to 394 healthy subjects. He then gave them nose drops containing several types of cold virus. The chances of getting cold symptoms turned out be amazingly predictable from the test scores over an almost two to one range.

A similar experiment (Cohen '97), published in the Journal of the American Medical Association, found that people with poor social connections were four times as likely to come down with cold symptoms after intentional exposure to a cold virus than people with a wide variety of close friends. Major diseases, cancer and even accidents have been similarly linked to emotional reactions.

Emotional reactions are mediated by ancient chemical messengers in your bloodstream called peptides. To date some 88 different peptides have been identified (Pert '97). Many of these, such as endorphins, are directly associated with emotions. Each of your immune cells have receptors for all of these chemical messengers as does your gut and virtually all of your internal organs. They are in two-way communications with your brain but in particular with your limbic system, where 85-95% of the receptors are concentrated. This ancient part of your brain is the seat of your deep emotions and instinctive drives.

Evolution works by culling the weak and preserving the strong. Mating battles in some species allow only the strongest to reproduce. Predators cull the weak in others. Perhaps the weakening of the human immune system by feelings of helplessness is nature’s way of culling the outcasts and the unsuccessful to improve the breed. One massive study in Finland examined the health records of 96,000 widowed people and found that their probability of dying was actually doubled in the week after losing their mate.

Feelings of pleasure and well-being have the opposite effect. They indicate that you are thriving and your immune system responds by working at peak efficiency so that you can survive and reproduce. The feeling of exultation that follows successfully dealing with a challenge actually energizes your immune system. Stress which can be dealt with thus actually helps you to maintain good health.

The opposite of pleasure and well-being is hopelessness. Just as animals separated from the herd often quickly die from disease, humans who feel chronic hopelessness are extremely vulnerable to disease and even cancer. Experiments have shown that your immune system is significantly weakened by helpless reactions to stress yet can actually be strengthened by stress which is dealt with successfully.

This effect can be demonstrated experimentally on rats using an ingenious apparatus to induce the feelings of helplessness. Yes, rats can feel helpless just like we do when they are given an unpleasant stress which they have no power to control. The apparatus used consists of special pairs of cages wired to give the rat in each cage identical random shocks through its feet. One of the rats has control of the shocks because he has a bar in his cage that stops the shocks in both cages when he presses it. The helpless rat receives exactly the same shocks but the bar in his cage does nothing to stop them. When a cancerous tumor is implanted under the rat’s skins, only 27% of the helpless rats can reject it compared to 63% of the rats with control. Rats receiving no shocks at all reject the tumor 54% of the time.

Experiments on humans are necessarily much less direct, but they confirm that evolution has given us the same tendency for our immune response to give up when we experience feelings of helplessness. Helplessness even slows the healing of wounds. In a 1995 Lancet article, Kiecolt-Glaser compared the rate of healing of wounds of long-term caregivers with normal controls. The caregivers were people who had spent years of their lives caring for demented relatives. The feeling of helplessness resulting from their situation showed its effects in significantly slower healing of their (punch biopsy) wounds. After six weeks, 55% of the wounds of the control subjects were healed verses only 17% for the caregivers.

In one Finnish study (Everson '96), 2428 men aged 42 to 60 were tested for helplessness. When health status was checked six years later, the men with high helplessness scores were 3.4 times as likely to have died than those with low scores. When the people with a previous history of cancer, diabetes, respiratory or heart disease were excluded, the results were even stronger. Healthy people with low scores were six times as likely to have died than those with high scores.

Natural Killer Cell Activity

One important part of your body's immune system is the natural killer cells. These amazing fighting units have the ability to recognize and selectively kill both cancer cells and virus-infected cells. Experimenters have actually measured variations in natural killer cell activity based on interactions between stress and attitude. For example, Dr. Steven Locke at Harvard Medical School questioned subjects about stressful events in their life and also about their psychiatric symptoms of distress. He then took blood samples and used them to measure their natural killer cell activity. The subjects were sorted into four equal-sized groups according to the level of their stress and the degree of their symptoms. The median killer cell activities measured for the four groups were as follows:

Group Natural Killer Cell Activity
Good coping (high stress/low symptoms) 22.5
Lucky (low stress/low symptoms) 15.1
Neurotic (low stress/high symptoms) 10.6
Bad coping (high stress/high symptoms) 7.5

The killer cell activity level of the group with high stress and low symptoms was three times higher than those with high stress and high symptoms.( Locke 1984, p. 448) People under stress who know how to deal with it emotionally thus appear to have more immune activity than even unstressed people with poor mental habits.

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Copyright 1997 Thomas R. Blakeslee. All rights reserved. Revised: February 19, 2004.