The Dialog Between the Brain and the Body

Ester Fride (right) with her late brother Ies (CF)

Psychosomatic medicine refers to the view that psychological factors are involved in health and disease. The complex interaction between the brain and the body has been recognized for centuries. More recently, a whole new area within medicine has sprung up, called ‘Behavioral Medicine,’ according to which, disease is not just a direct result of a physical insult, but the eventual outcome of a combination of physiological and psychosocial factors, such as stress, personality and genetic predisposition to disease (see Figure 1).

An example is the development of ulcers: Experiments performed in humans as well as in animals have indicated that one of the contributing factors to the development of ulcers is psychological stress or tension. In addition, personality, gastric secretions and genetic predisposition contribute to the ulceration process.

How does the brain communicate with the body? A major way in which our body fights off assaults by environmental hazards, such as invading viruses or bacteria, is by activation of the immune system. Thus the immune system is considered a major mediator between brain and body. Although once considered an ‘unscientific’ area of interest, today, laboratories investigating the regulatory role of the brain in immune function, are found in major research institutes and universities all over the world. Thus a host of new experimental findings have produced evidence that the brain, and processes which it commands such as thoughts, mood and anxiety, significantly influence functioning of the immune system and development of disease.

How is the effect of the brain on the immune system accomplished? Some of the major findings include the observation that there are nerve endings impinging on immune organs such as the spleen and the cells therein. This implies that the nervous system (the brain) has the ability to influence the activity of these organs. In addition, the brain can influence immune defense by sending out chemical messengers, such as hormones, into the blood stream. These ‘stress’ hormones are recognized by immune cells and organs, by means of specific ‘receptors.’ The hormones attach themselves to these receptors and subsequently affect cellular activity.

When we are going through tense times such as during university examinations, certain parts in the brain are activated and we feel ‘stressed’; in accordance with our mental state we may behave differently than when we were relaxed. At the same time, these brain regions send out messages to release stress hormones into the blood stream. As a result, the body is ‘informed’ of the stress that the brain is experiencing.

Now you would expect that the brain would coax the immune system, under these stress conditions, to give us extra strength to cope with invading organisms such as bacteria and viruses. But, especially when the state of stress is prolonged, the opposite happens: The immune system is slowed down. In a series of experiments performed over a number of years, it has been shown that the immune systems of medical students were weakened when studying for final exams. This was observed both for cellular functions (test tube experiments), as well as when the frequencies and severity of viral or bacterial infections were assessed.

The control of the brain over the immune system goes even further: We can actually ‘learn’ to influence our immune system (similar to ‘biofeedback’, when we learn for example, how to keep our blood pressure down). Thus rats could be trained (‘conditioned’) to alter immune function at a certain signal such as a light or the sound of a bell. Such observations gave rise to propositions that we can learn behavioral techniques to fight immune-related diseases. For instance, there is experimental evidence that children who suffer from recurrent colds and flu displayed significant improvement when stress levels were reduced and when they were taught to ‘control’ their colds by ‘imagining’ that tiny versions of themselves could enter their own bodies in order to strengthen their germ-fighting immune tools (Hewson-Bower and Drummond 2001). The latter behavioral technique is called ‘guided imagery.’

To summarize thus far, both basic and clinical research indicate that psychological processes may affect physiological states, mainly it seems, by means of the immune system.

In addition and even more intriguingly, recent experiments have provided evidence that the brain and the immune system also communicate in the opposite direction: Events that occur in the body are relayed to the brain and thus ‘we’ are informed of what is happening to our physical health. An example is when a virus invades our body. How do we know about this ‘invasion’, especially in the initial stages, when we don’t feel pain or discomfort?

Immunologists have known for years that when immune cells sense an ‘invader’ such as a virus, they will inform each other using chemical messengers called ‘interleukins.’ It turns out that these interleukins are not only travelling around the body in order to inform the various immune cells of the infection, but some of them (such as ‘interleukin #1’) also enter the brain, attach themselves to specific receptors and thus inform the brain about what is going on in the body.

Why is it important for the brain to know about the state of health of the body? ‘Knowing’ that the body is infected, the brain responds with the appropriate behaviors: Motor activity and social interactions are slowed down, sleeping time is increased and appetite decreased. In addition it instructs the body to increase its temperature (fever). These measures help us remove the infection from the body.

In summary, a bi-directional communication system between the brain and the immune system is now widely recognized by the scientific community. However, the implications for day-to-day management of health and disease remain to be clarified.

I believe that the recognition of this communication system is a two-edged sword: On the positive side, it gives us hope and courage that we are at least somewhat in control of our health, if we can muster the right state of mind. But on the negative side, when we are not doing well physically, does that mean that we were not able to get in control or were not positive enough? Did we fail? Should we feel weak and guilty?

Perhaps when we look at the range and type of diseases which afflict mankind, we can obtain a perspective. Just as there are traits which are solely genetically determined at the time of conception, such as eye color, there are diseases which are handed down genetically, in a straightforward way with a predictable onset, course and ending. An example is Huntington’s disease, a terrible and fatal neurological disorder. Heart disease and psychiatric conditions such as depression and schizophrenia, on the other hand, develop as a result of both genetic predisposition and environmental factors such as stress, drugs, parenting, etc. (see Figure 2).

So what about CF? The cause is clearly genetic, but the course of the disease is influenced by environmental factors including medical treatment, lifestyle and physical environment (the Swiss mountains as compared to downtown London?). Due to the nature of the disease, patients with CF must diligently attend to all of the negative physical manifestations such as infection, weight loss, etc. with the help of highly trained physicians. Nonetheless, the evidence described above suggests that more attention should be given to the patients’ psychosocial environment (see Figure 1). If CF-ers are feeling well emotionally, it would be logical to assume, based upon all of the current scientific evidence, that this would have a positive effect on the severity of the physical manifestations of the disease.

Taken together, I think it is fair to say that when we look at the “genetic versus environment” scale of the causation of disease (Figure 2), cf is situated closer to the “genetic only” end of the scale than to the “environment only” pole.