Practice recommendations
- Heighten your awareness of nonlinear patient behaviors including sensitivity to minor changes, resistance to change, sudden dramatic change in behavior, and intermittent catastrophes.
- Nonlinearity means we should expect the unexpected but limit unpredictability through in-depth knowledge of patients and context.
- Reinforce positive attractors, use small well-timed interventions, and encourage healthy variability and nonlinearity.
Had Sir Isaac Newton attempted family medicine, he likely would have been uncomfortable with its nonlinear aspect typified by unpredictable disease courses and treatment responses.
Linearity forms the basis of our knowledge… Life in a Newtonian world is ordered and predictable, where causes are directly linked to effects and behavior is linear or cyclic (periodic). In this world, stability and predictability define a healthy system. Furthermore, by understanding the parts of a system, we understand the system. As physicians, we are trained to expect this linear, predictable, reductionistic view of health.
…but it does not reflect the human system. However, humans are complex adaptive systems, characterized by multiple interconnected and interdependent parts at levels from the microscopic to the community. Interactions change over time, producing synergistic nonlinear behavior as components periodically self-organize into functional groups.
TABLE 1 compares the Newtonian world view with that of complexity science. Although all of the characteristics of complexity science are relevant to family physicians, this article will focus on the nonlinear behavior of patients as the visible, unpredictable, and often frustrating manifestation of the complexity characteristics. TABLE 2 defines specific characteristics of nonlinearity.
In understanding nonlinearity—as depicted in 4 patient cases presented here—family physicians can learn to
- expect the unexpected
- reduce unpredictability by learning about patients and their context
- attack patient resistance by seeking epiphanies or using positive attractors
- recognize the sensitivity of our patients’ trajectories and use or anticipate it
- promote the healthy benefits of nonlinearity.
TABLE 1
Basic tenets of Newtonian and complexity world views
| CHARACTERISTIC | NEWTONIAN | COMPLEXITY |
|---|---|---|
| Cause-and-effect | Every effect has a clear cause | Events not always linked to a cause |
| Predictability | Predictable | Not predictable |
| Dynamics | Linear | Nonlinear |
| Whole vs parts | Whole equals sum of parts | Whole is not the sum of its parts |
| Adaptation to stress | Predictable, logical stress-reducing behaviors | Unpredictable, sometimes detrimental responses |
| Leveraging change | Predictable response to intervention | Multiple, well-timed interventions may be necessary |
TABLE 2
Nonlinear characteristics relevant to family practice
| CHARACTERISTIC | DEFINITION | CLINICAL EXAMPLE |
|---|---|---|
| Sensitivity to initial conditions | The phenomenon wherein a small change initially can send the system on a new trajectory, drastically changing the system’s subsequent performance | Panic attack experienced without a perceived reason can lead to agoraphobia, whereas a similar but “explainable” attack may be perceived by the patient as merely annoying |
| Attractor | Set of values to which a system migrates over time. An attractor limits the range of possible behaviors of a system and prevents random activity, but does not dictate the specific path the system follows | Self-destructive behavior—eg, alcoholism—is governed partly by a learned set of beliefs and expectations (negative attractor) that limit a person’s ability to make healthy choices. Treatment may be aided by substitution of a positive attractor—eg, well-being of family |
| Bifurcation | Sudden qualitative change in the behavior of a system as the system reaches a “tipping point” | Epiphanies, such as those realized in the decline of a relative who shares a disease, can provide leverage for change in behavior |
| Self-organized systems | System of tenuously linked parts at the edge of stability. Complex interrelationships among components produce a system in which a single event can result in a cascading effect due to the coupling of components | Detrimental self-organized behavior may manifest in a person’s over-reaction to a minor stressor. Using multiple stress reducing techniques and encouraging connectedness with others can introduce healthy, chaotic variability |
Nonlinearity as a truer model of health
Although our basic medical knowledge is built on a reductionistic approach that assumes linear dynamics, our models rarely account for more than 30% of whatever outcome we are investigating. Clinical providers are often faced with the unexpected.
Although linearity suggests that illness should respond in predictable ways regardless of the environment, family physicians know that context is critical. In addition, the human condition is often nonlinear; nonlinear dynamics (chaotic or random dynamics) have been documented in physiology,1 psychology,2,3 sociology,4 business,5-7 and economics.8
In fact, nonlinear dynamics are often a sign of health. For example, mood may vary in linear patterns among patients with affective disorders; therapy for mood disorders may work by changing the pathological linear dynamics in mood into more healthy nonlinear dynamics.9 Linear (or periodic) dynamics often indicate a pathological condition.10,11
As science and medicine begin to embrace the nonlinearity of complexity science, we must anticipate, recognize, and apply nonlinearity to the care of our patients. This is particularly important for family physicians.
Applying nonlinearity to patient cases
The following cases demonstrate characteristics of nonlinear dynamics (TABLE 2).