According to the biopsychosocial model, disease is the dysfunctional resultant of various fields of human function (biological, psychological, behavioral, socioeconomic). This article deals with the psycho-biological field of Psychosomatic research, namely, the effect of stress on the body. The human organism, in the prospect of evolution, has developed biological mechanisms for maintaining its homeostasis (ομοιόσταση), in its interchange with the stressor stimuli. This process is called allostasis. The response to mild – short-term stress induces activation of the hypothalamic – pituitary – adrenal axis, the sympathetic system and the immune system; a process that proves beneficial to the body. On the contrary, exposure to traumatic or chronic stress, with subsequent overactivation of the body's allostatic mechanisms, wears out its homeostatic ability and initiates pathophysiological mechanisms that pave the way for the development of physical and mental illness. The above procedure is called allostatic load or, in its most severe form, allostatic overload. More specifically, the experience of traumatic stress, either in childhood or in adulthood, induces dysregulation of neuroendocrine pathways in the Central Neural System (CNS), as well as immune dysfunction, and is associated with more frequent development of psychiatric and medical pathology, in a dose-dependent way. On the other hand, exposure to chronic repetitive stress induces neurobiological lesions at the level of the CNS, which undermine the body's very ability to respond to stress. At the same time, chronic stress has been associated with increased morbidity from major medical disorders, such as diabetes mellitus, obesity, metabolic syndrome and cardiovascular disease, through a variety of pathophysiological pathways. Finally, chronic stress causes dysfunction of the body's immuno-protective mechanisms, while at a cellular level, it induces oxidative stress and cellular apoptosis. However, regardless of the quantity and quality of the stressor stimuli, it has also emerged that the individual's personal characteristics judge the vulnerability to stress, too. Psychiatrists must insist on the scientific documentation of the biopsychosocial model, so that they can raise awareness amongst the medical community, aiming at a holistic care of the patients.

KEYWORDS: biopsychosocial model, allostasis, allostatic load, trauma, chronic stress, psychosomatic disease

Ioannis Tollos, Angeliki Theodorakopoulou, Georgios N. Christodoulou


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