For more than a century, the biomedical model — derived from Louis Pasteur's germ theory of disease — has been the dominant force in Western medicine. Postulating that all disease is a product of a biologic defect often initiated by a biologic pathogen, the model is reductionist, seeking to explain all disease in biologic terms. It is also exclusionary, since any symptoms that cannot be explained in biologic terms are excluded from consideration. This has led to mind-body dualism in which "mental" disorders are often excluded from the primary concerns of Western medicine unless they can be explained by an underlying somatic defect.1
The biomedical model was hugely successful. At the beginning of the 20th century, the leading causes of death were tuberculosis, pneumonia, influenza and diarrhea. The model's germ theory of disease essentially eliminated these infectious diseases as the primary cause of death. By the end of the 20th century, people died of chronic disease — heart disease, cancer and stroke2— and life expectancy had increased from 47 years in 1900 to 77 years in 2000.3
Although George Engel proposed a new medical model — the biopsychosocial model — in 1977, U.S. health care remained entrenched in the biomedical model until very recently. Several factors have contributed to the current paradigm shift occurring in medicine. Americans continue to die primarily from chronic disease, and the biomedical model has failed to successfully address this modern health-care challenge. Almost one in two U.S. adults has a chronic disease, and treating chronic illness accounts for 75 percent of our health-care costs.4 Further, U.S. health-care costs continue to escalate5 with little positive impact on health; the United States leads the world in health-care spending, but U.S. life expectancy is equivalent to that of Cuba.6 The role of behavior — both patient and provider behavior — in disease etiology, prevention and management has become increasingly apparent; tobacco and obesity are the leading causes of death in the United States,7 and medical errors are ranked eighth.8
In response, medicine is now embracing the biopsychosocial model, emphasizing patient-centered care delivered by interdisciplinary provider teams that include mental health expertise. The Affordable Care Act requires that essential health benefits include mental health, preventive and wellness services, and chronic disease management.9 The MCAT (Medical College Admission Test) will include the same number of items on psychological, social and biologic foundations of behavior as it has on biology and biochemistry.10 And accredited medical schools are now required to teach patient-provider communication skills, the medical impact of common societal problems, the impact of patient culture and beliefs, and the impact of provider bias and beliefs.11
This paradigm shift offers numerous opportunities for psychologists in health care, medical education and health research. However, for psychology to take advantage of these opportunities, it must abandon the mind-body dualism promulgated by the biomedical model that unfortunately characterizes many of our training programs, much of our solo professional practice and even some of our research. Like physicians, psychologists need to embrace the biopsychosocial model, train the next generation for inter-professional practice and ensure that our future scientists can function effectively on interdisciplinary science teams.
1 Engel, G. Science, 1977, 196:129-136.
7 Mokdad et al. JAMA. 2004;291:1238-1245
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