Functional Medicine: A Twenty-First Century Model of Patient Care and Medical Education

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Chapter 2 Functional Medicine

A Twenty-First Century Model of Patient Care and Medical Education

In this chapter, the basic principles, constructs, and methodology of functional medicine are reviewed. It is not the purpose of this chapter to recapitulate the range and depth of the science underlying functional medicine; books and monographs covering that material in great detail are already available for the interested clinician and for use in health professional schools (see Bibliography at the end of the chapter). The purpose is to describe how functional medicine is organized to deliver personalized systems medicine and is equipped to respond to the challenge of treating complex chronic disease more effectively.

image What is Functional Medicine?

Functional medicine encompasses a dynamic approach to assessing, preventing, and treating complex chronic disease. It helps clinicians of all disciplines identify and ameliorate dysfunctions in the physiology and biochemistry of the human body as a primary method of improving patient health. This model of practice emphasizes that chronic disease is almost always preceded by a period of declining function in one or more of the body’s physiologic organizing systems. Returning patients to health requires reversing (or substantially improving) the specific dysfunctions that contributed to the disease state. Those dysfunctions are, for each of us, the result of lifelong interactions among our environment, our lifestyle choices, and our genetic predispositions. Each patient, therefore, represents a unique, complex, and interwoven set of influences on intrinsic functionality that, over time, set the stage for the development of disease or the maintenance of health. To manage the complexity inherent in this approach, functional medicine has adopted practical models for obtaining and evaluating clinical information that leads to individualized patient-centered therapies.

Historically, the word “functional” was used somewhat pejoratively in medicine. It implied a disability associated with either a geriatric or psychiatric problem. The authors suggest, however, that this is a very limited definition of an extremely useful word. Medicine has not really produced an efficient method for identifying and assessing changes in basic physiologic processes that produce symptoms of increasing duration, intensity, and frequency, although it is known that such alterations in function often represent the first signs of conditions that, at a later stage, become pathophysiologically definable diseases. By broadening the use of functional to encompass this view, functional medicine becomes the science and art of detecting and reversing alterations in function that clearly move a patient toward chronic disease over the course of a lifetime.

One way to conceptualize where functional medicine falls in the continuum of health and health care is to examine the functional medicine “tree.” In its approach to complex chronic disease, functional medicine encompasses the whole domain represented by the graphic shown in Figure 2-1, but first addresses the patient’s core clinical imbalances (found in the functional physiologic organizing systems), the fundamental lifestyle factors that contribute to chronic disease, and the antecedents, triggers, and mediators that initiate and maintain the disease state. Diagnosis, of course, is part of the functional medicine model, but the emphasis is on understanding and improving the functional core of the human being as the starting point for intervention.

Functional medicine clinicians focus on restoring balance to the dysfunctional systems by strengthening the fundamental physiologic processes that underlie them and by adjusting the environmental and lifestyle inputs that nurture or impair them. This approach leads to therapies that focus on restoring health and function, rather than simply controlling signs and symptoms.

Lifestyle and Environmental Factors

The building blocks of life, as well as the primary influences on them, are found at the base of the functional medicine tree graphic (see Figure 2-1). When we talk about influencing gene expression, we are interested in the interaction between lifestyle and environment in the broadest sense and any genetic predispositions with which a person may have been born—including the epigenome.* Many environmental factors that affect genetic expression are (or appear to be) a matter of choice (such as diet and exercise); others are very difficult for the individual patient to alter or escape (air and water quality, toxic exposures); and still others may be the result of unavoidable accidents (trauma, exposure to harmful microorganisms). Some factors that may appear modifiable are heavily influenced by the patient’s economic status—if you are poor, for example, it may be impossible to choose more healthful food, decrease stress in the workplace and at home, or take the time to exercise and rest properly. Existing health status is also a powerful influence on the patient’s ability to alter environmental input. If you have chronic pain, exercise may be extremely difficult; if you are depressed, self-activation is a major challenge.

The influence of these lifestyle and environment factors on the human organism is indisputable,1,2 and they are often powerful agents in the battle for health. Ignoring them in favor of the quick fix of writing a prescription—whether for pharmaceutical agents, nutraceuticals, or botanicals—means the cause of the underlying dysfunction may be obscured but not eliminated. In general terms, the following factors should be considered when working to reverse dysfunction or disease and restore health:

Fundamental Physiologic Processes

There are certain physiologic processes that are necessary to life. These are the “upstream” processes that can go awry and create “downstream” dysfunctions that eventually become disease entities. Functional medicine requires that clinicians consider these in evaluating patients, so that interventions can target the most fundamental level possible. These processes are:

These fundamental physiologic processes are usually taught early in health professions curricula, where they are appropriately presented as the foundation of modern, scientific patient care. Unfortunately, subsequent training in the clinical sciences often fails to fully integrate knowledge of the functional mechanisms of disease with therapeutics and prevention, emphasizing organ system diagnosis instead.3 Focusing predominantly on organ system diagnosis without examining the underlying physiology that produced the patient’s signs, symptoms, and disease often leads to managing patient care by matching diagnosis to pharmacology. The job of the health care provider then becomes a technical exercise in finding the drug or procedure that best fits the diagnosis (not necessarily the patient), leading to a significant curtailment of critical thinking pathways: “Medicine, it seems, has little regard for a complete description of how myriad pathways result in any clinical state.”4

Even more important, pharmacologic treatments (and even natural remedies) are often prescribed without careful consideration of their physiologic effects across all organ systems, physiologic processes, and genetic variations.5 Pharmaceutical companies exploit this weakness. We do not see drug advertisements that urge the practitioner to carefully consider the impact of all other drugs being taken by the patient before prescribing a new one! The marketing of drugs to specific specialty niches, and the use of sound bite sales pitches that suggest discrete effects, skews health care thinking toward this narrow, linear logic, as notably exemplified by the cyclooxygenase-2 inhibitor drugs that were so wildly successful on their introduction, only to be subsequently withdrawn or substantially narrowed in use due to collateral damage.6,7

Core Clinical Imbalances

The functional medicine approach to assessment, both before and after diagnosis, charts a course using different navigational assumptions. Every health condition instigates a quest for information centered on understanding when and how the specific biological system(s) under examination spun out of control to begin manifesting dysfunction and/or disease. Analyzing all the elements of the patient’s story, the signs and symptoms, and the laboratory assessment through a matrix focused on functionality requires analytic thinking and a willingness on the part of the clinician to reflect deeply on underlying biochemistry and physiology. The foundational principles of how the human organism functions—and how its systems communicate and interact—are essential to the process of linking ideas about multifactorial causation with the perceptible effects called disease or dysfunction.

To assist clinicians in this process, functional medicine identified and organized a set of core clinical imbalances that are linked to the fundamental physiologic processes (organizing systems). These serve to marry the mechanisms of disease with the manifestations and diagnoses of disease. Many common underlying pathways of disease are reflected in these clinical imbalances. The following list of imbalanced systems and processes is not definitive, but some of the most common examples are provided. We recommend that the organizing systems be considered in the order as shown in the following:

Assimilation Imbalances

Defense and Repair Imbalances

Energy Imbalances

Biotransformation and Elimination Imbalances

Communication Imbalances

Structural Integrity Imbalances

Using this construct, it becomes much clearer that one disease and/or condition may have multiple causes (i.e., multiple clinical imbalances), just as one fundamental imbalance may be at the root of many seemingly disparate conditions (Figure 2-2).

image

FIGURE 2-2 Core clinical imbalances—multiple influences.

(Courtesy of the Institute for Functional Medicine.)

The most important precept to remember about functional medicine is that restoring balance—in the patient’s lifestyle and/or environment and in the body’s fundamental physiologic processes—is the key to restoring health.

Antecedents, Triggers, and Mediators*

What modern science has taught us about the genesis of disease can be represented by three words: triggers, mediators, and antecedents. Triggers are discrete entities or events that provoke disease or its symptoms. Microbes are an example. The greatest scientific discovery of the nineteenth century was the microbial etiology of the major epidemic diseases. Triggers are usually insufficient in and of themselves for disease formation; however, host response is an essential component.

It is, therefore, the functional medicine practitioner’s job to know not just the patient’s ailments or diagnoses, but the physical and social environment in which sickness occurs, the dietary habits of the person who is sick (present diet and pre-illness diet), his or her beliefs about the illness, the impact of illness on social and psychological function, factors that aggravate or ameliorate symptoms, and factors that predispose to illness or facilitate recovery. This information is necessary for establishing a functional treatment plan.

Identifying the biochemical mediators that underlie host responses was the most productive field of biomedical research during the second half of the twentieth century. Mediators, as the word implies, do not cause disease. They are intermediaries that contribute to the manifestation and/or continuation of disease. Antecedents are factors that predispose to acute or chronic illness. For a person who is ill, antecedents form the illness diathesis. From the perspective of prevention, they are risk factors. Knowledge of antecedents provides a rational structure for the organization of preventive medicine and public health.

Medical genomics seeks to better understand disease by identifying the phenotypic expression of disease-related genes and their products. The application of genomic science to clinical medicine requires the integration of antecedents (genes and the factors controlling their expression) with mediators (the downstream products of gene activation). Mediators, triggers, and antecedents are not only key biomedical concepts, they are also important psychosocial concepts. In person-centered diagnosis, the mediators, triggers, and antecedents for each person’s illness form the focus of clinical investigation.

Antecedents and the Origins of Illness

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