Abstract：In the 1970s, the American doctor George L.Engel challenged the dominant biomedical model in clinical medicine and put forward the "bio-psycho-social medical model", from which the concept of "psychosomatic disease" caught people′s attention. In this concept, mental illness is the "cause" and physical symptoms are the "effect", although the physical symptoms of patients with psychosomatic diseases do not have clear biological abnormalities, their clinical symptoms are real, such diseases are called "functional diseases". Until now, it is still believed that in psychosomatic diseases, psychological disorders as a cause of illness, like somatic diseases, do not have obvious biological abnormalities. The author believes that psychological disorders, as a kind of disease, may have biological abnormalities, which are related to the changes in the limbic system of the human brain, especially the hippocampus. At the same time, it is further believed that the changes in the limbic system and hippocampus are not only related to the functional diseases of the body, but also related to some organic diseases of the body. The purpose of this paper is to show that the relationship between physical functional diseases and psychological disorders is not a causal relationship, but both may be the result of changes in the hippocampus, and the persistence of these diseases may in turn promote the deterioration of hippocampal lesions, forming a vicious circle.
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