Mental processes and psychiatric illness have significant, measurable effects on the course and outcome of medical conditions. The cause of this phenomenon is that the brain continuously integrates internal and external information and adjusts the body’s physiological processes to meet expected challenges. Although the adjustments directed by the brain are genetically programmed to be adaptive, under certain conditions they can have deleterious effects. For example, the neuroplastic changes precipitated by periods of chronic stress, such as childhood abuse or military combat, can have adverse physiological consequences that last a lifetime. In addition, as the articles in this issue document, comorbid psychiatric illnesses have a significant effect on the treatment costs and outcomes of a variety of medical conditions.
In 1977, the late George Engel proposed his now famous biopsychosocial model to guide the conceptualization and management of medical illness.1 Engel’s model was in part a reaction to the strict emphasis on measurable biological phenomena that characterized the practice of medicine in his time. Scrupulous adherence to scientific principles had led to rapid advances in the understanding and treatment of medical conditions; however, it sometimes produced a relatively impersonal physician-patient relationship and neglected psychosocial factors that, although not scientifically accessible at the time, were clearly important in deciding the outcome of medical illnesses.
Scientific research in the past 32 years has not only confirmed Engel’s view that psychosocial factors contribute to medical illness but has defined the cellular and molecular pathways that mediate these effects. The brain, which controls and integrates all of the body’s physiological processes, continuously modulates the physical substrates upon which disease processes operate. The scientific evidence that demonstrates how mental processes produce physiological effects now makes it untenable from both theoretical and practical viewpoints to ignore psychosocial factors when addressing medical conditions.
This issue of Psychiatric Annals addresses brain-body interactions and their effects on medical outcomes. The current issue focuses on the theoretical aspects of brain-body interactions, with emphasis on the mechanisms by which the brain modulates physiological processes. The second part in this series will focus on practical applications of integrated medical-behavioral management in a variety of settings.
This issue begins with part 1 of a two-part series of reviews by Drs. George I. Viamontes and Charles B. Nemeroff on the basic biology of brain-body interactions, a field to which Dr. Nemeroff has made numerous scientific contributions (see page 975). The first review, which appears in this issue, “Brain–Body Interactions: The Physiological Impact of Mental Processes — The Neurobiology of Stress Responses.” It describes the organization and biological actions of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system, which are two of the major pathways that translate mental states into physiological events. The neurobiology of bodily responses to psychosocial stress, and the health consequences of such responses, is also detailed. An understanding of the stress response is critical for mental health clinicians, as well as for primary care and specialty physicians, because it defines one of the most medically significant links between brain and body. In addition, it provides an important rationale for the development of integrated medical-behavioral programs for the management of medical conditions. The second part of this review, “Major Body Systems and the Brain,” will appear in the January 2010 issue of Psychiatric Annals.
Dr. Claudia Troesch Viamontes has contributed an article, “The Sickness Response: An Adaptive Brain-Body Reaction to Medical Illness” (see page 985). Dr. Viamontes discusses a critical aspect of the brain’s response to medical conditions, namely the triggering of sickness behavior. The experience of “being sick” is one of the most unpleasant and debilitating aspects of medical illness. Sickness responses are a consequence of the continuous dialog between the brain and the immune system, which is conducted through the common language of cytokines and cytokine receptors. Cytokines are specialized peptides that mediate communications among the various immune system cells, as well as between immune system cells and the brain. Whenever an immune response is launched against a pathogen, its progression leaves behind a cytokine “footprint” that the brain can detect and interpret. When the brain detects immune system activity, it triggers a genetically programmed set of subjective sensations and behavioral tendencies that is known as the sickness response. Sickness responses, as demonstrated by interferon treatment of medical conditions, can be remarkably similar to depression, and can indeed progress to a fully diagnosable major depressive disorder (MDD). An understanding of the sickness response can be critical when addressing the psychobehavioral symptoms of patients with chronic medical illnesses or of patients who are receiving immunomodulatory therapies, such as interferon injections.
Drs. Glen O, Gabbard and Valdesha Ball have contributed an article, “Physical and Medical Dimensions of Borderline Personality Disorder and the Effect of Treatment” (see page 997). Borderline personality disorder (BPD) is a debilitating psychiatric condition with a multifactorial etiology, although, as the article indicates, 60% to 80% of BPD patients have been subjected to childhood trauma. Chronically abused BPD patients demonstrate long-term physiological changes that include ACTH hyperresponsiveness, as well as amygdalar hyperactivity, combined with orbitofrontal cortex hypoactivity. The orbitofrontal cortex is reciprocally connected with the amygdala and is normally an important modulator of amygdalar function. These observed anomalies may be part of the mechanisms that mediate the affective instability and impulsivity that characterize BPD. BPD is associated with high utilization of medical services and emergency room visits. Treatment of BPD patients in a structured, partial hospitalization setting was effective in reducing medical costs and ER visits. This article has important practical applications because it suggests effective treatments for stabilizing BPD patients that will decrease subjectively experienced symptoms and the utilization of medical services.
Drs. Karen M. Palaszynski and Charles B. Nemeroff have contributed an article, “The Medical Consequences of Child Abuse and Neglect” (page 1004). This article reviews the scope and consequences of child abuse and defines the mechanisms by which child abuse can cause permanent physiological alterations. These changes, in turn, increase susceptibility to a variety of medical conditions. For example, autoimmune diseases, obesity, cardiovascular disease, and increased inflammatory responses are all positively correlated with a history of early life stress and trauma. Child abuse, therefore, not only affects subsequent mental functioning, but also impairs physiological adaptation and can increase the risk of adverse medical outcomes over a patient’s lifetime.
Drs. Ronald Beach, Gregory A. Bayer, and Brett Hart have contributed an article, “The Effect of Psychiatric Illness on Medical Outcomes” (see page 1013). This article analyzes a large commercial patient database to investigate the hypothesis that medical costs increase with psychiatric comorbidities. Results indicated that medical costs more than doubled for both men (2.27 times; t = −11.92; P < .001) and women (2.28 times; t = −17.00; P < .001) in the year following the identification of dual medical and psychiatric diagnoses, as compared with similar medical patients without a psychiatric diagnosis. Comorbid substance abuse diagnoses had a particularly marked effect, as they tripled medical costs for both men (3.05 times; t = −12.05; P < .001) and women (3.09 times; t = −14.61; P < .001). This study replicates earlier analyses and confirms the practical effect of psychiatric conditions on medical outcomes.
The current issue of Psychiatric Annals, taken as a whole, provides a compelling overview of the link between mental and physiological processes and outlines some of the key biological pathways through which these effects are mediated. It is clear that to optimize outcomes, medical treatment must address psychosocial variables and psychiatric comorbidities. The biopsychosocial model of medical illness, proposed by Engel more than 30 years ago, has now acquired a scientific infrastructure and provides a theoretical foundation for medical-behavioral integration in the delivery of patient care.
- Engel G. The need for a new medical model: a challenge for biomedicine. Science. 1977;196(4286):129–136. doi:10.1126/science.847460 [CrossRef]