Psychoneuroimmunology: The study of the connections between the mind and the neural, immune and endocrine (hormonal) systems.
The basic concept of psychoneuroimmunology is the concept that the mind and body are inseparable. It follows that stress affects the body's ability to resist disease. The brain influences all sorts of physiological processes once thought not to be centrally regulated. There are effects of psychological factors on many diseases including rheumatoid arthritis, diabetes, hypertension, heart disease, and inflammatory bowel disease.
Among the pioneers of this field were Dr. George Engel at the University of Rochester School of Medicine and Dentistry and Dr. George F. Solomon of Harvard Medical School. The field is sometimes called psychoimmunology. It is part and parcel of psychosomatic medicine.