The Ghost in the Machine

The placebo effect, multiple personality disorder, and spontaneous remissions give us important clues about “the forces that operate in vis medicatrix naturae.” One of the things they teach is that to understand the nature of the body’s self-healing intelligence, we must understand the nature of the mind and the relationship between the mind and body. When belief, or what we might term ‘a stable state of knowing’ is involved, the mind appears unreasonably capable of shaping physiological outcomes. Yet, in trying to understand the mechanics that turn ‘knowing’ into healing, we run up against the limitations of the underlying theoretical model of allopathic medicine.

The relationship between mind and body is an age-old puzzle. For centuries, the practice of medicine has been influenced by a conceptual heritage from Descartes – the dualist notion of mind and body. Descartes viewed mind and body as two separate substances: res cogitans is a thinking substance which is unextended and indivisible, and res extensa denotes all the physical substances, which have extension in space, i.e. they can be measured and analysed, and which exist independently of res cogitans. In this model, the human body functions completely independently of the mind. The human body, wrote Descartes, is a machine mad up of bones, sinews, veins, blood and skin, and fitted together “in such a way that even if there were no mind in it, it would still carry out all the operations that … do not depend upon the command of the will, nor therefore, on the mind.”

Although he considered mind and body as two separate essences, Descartes did not deny their ability to interact. The translation of a mental impulse into a physiological action is so commonplace that we don’t even think about it. If you decide to reach for a glass of water, your arm extends automatically and your hand grips the glass. Yet, from the point of view of the dualist model, this is an inexplicable phenomenon. How can a non-physical substance influence a totally separate physical substance? Descartes proposed that mind and body interact through the small part of the brain known as the pineal gland, but he neglected to answer the question of how the non-physical mind acts on the pineal gland.

In spite of its obvious shortcomings, variations of the dualist notion of mind and body influenced the practice of medicine in the centuries after Descartes. Early Greek physicians emphasized that some patients’ complaints had their root in mental factors, but after Descartes the mind was denied a role in the disease process. Cartesian dualism influenced the biomedical model which is still commonly accepted today. According to this model, physical disorders are afflictions brought about by a disruption of physiological processes, which in turn may result from bacterial or viral infection, biochemical imbalances, injury, etc. The mind is not a contributing factor.

The dualist model of mind and body had too many deficiencies to remain unchallenged, and many alternative models have since been proposed. In the twentieth century, the scientific community has come to regard the mind as a product of the interaction of matter. In this materialist model, mental events are explained with reference to purely physical principles – a thought is the end result of the complex interaction of neurophysiological processes.

“[Y]our joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules.” Says scientist Francis Crick, who shared a Nobel prize for discovering the structure of DNA. But if the mind is simply an outgrowth of physiological factors, again there is no apparent reason why it should play a role in the disease process. How could something pervasively influence that of which it is but a product?

Yet, the link between mental factors and the development of disease has been impossible to ignore. Researchers like Dr. Hans Selye, who introduced the stress concept, and Franz Alexander, who introduced the notion of psychosomatic disease, were among the early pioneers who tried to identify the mechanisms through which mental factors might lead to physiological disease. In the last 30 years, these attempts have been spearheaded by researchers in the multidisciplinary field of psychoneuroimmunology. This new field of research focuses on the interplay of psychosocial actions, brain processes, and the immune system.

Almost everywhere they have looked, researchers have found a smoking gun linking psychological factors with disease. If a randomly selected group of people are all exposed to the same infectious agent, such as a cold virus or streptococci bacteria, as few as one fifth of them may actually develop symptoms of infection. Heart disease appears to be more prevalent among individuals who have a high degree of anger, hostility, and cynicism. Depression, feelings of hopelessness, or repressed negative emotions may predispose a person to cancer. People with a pessimistic explanatory style, who tend to blame themselves for negative events and perceive the effects of these events as durable and pervasive, experience poorer health when they reach middle age. Social isolation appears to be especially marring; it is involved in the development of a whole range of diseases, including heart disease, cancer, depression, and arthritis.

In other words, environmental stressors are not the only factors that influence health. Internal ‘stress’, in the form of negative emotions or feelings of loneliness, plays a role as well. Simply being in good psychological health may provide the best protection of all against disease.