Is your practice really that predictable? Nonlinearity principles in family medicine

Case 4: Self-organized behavior

S.O. is a 40-year-old housewife with a long history of intermittent anxiety, usually in response to a family stressor. She presents with extreme apprehension and insomnia. On examination, she is restless and mildly tachycardic. Upon further questioning, she denies any recent adverse events but, in fact, reports that her husband recently received a promotion including a significant increase in salary. In reviewing her chart, you notice that you have diagnosed her with adjustment disorder with anxious mood on 3 previous occasions after adverse family stressors. However, her reactions have often been out-of-proportion to the level of stress and she has occasionally reported significant stressors (eg, death of a sister) without subsequent anxiety.

Neurologic systems tend to organize themselves in response to external events and internal models. These self-organized systems consist of tenuously linked parts at the edge of stability balanced between periodic and chaotic behavior. They react to stressors in patterned ways, but the magnitude of the reaction can vary from little or no response to a catastrophic reaction. Because such self-organization can be temporary, with groups periodically forming and dissolving, behavior over time is random without recurrent patterns.

With this patient, varying degrees of stress (even positive events) result in varying degrees of dysfunction with little relationship between the magnitude of stress and the magnitude of dysfunction. The periodic collapse in response to cumulative stress is not the only example of self-organized behavior.

Self-organization is believed to be critical in a variety of neuropsychiatric conditions from personality disorders² and conversion reactions to adult consequences of childhood adversity.²⁷ Patterns of detoxification in groups of alcoholics demonstrate self-organized behavior.²⁸ Self-organization is important to understanding self-regulation and behavior in families.^29,30 Even social interaction patterns among groups of patients on psychiatric wards show self-organized behavior as unstable groups form, dissolve, and reform.³¹

Implications for management. If non-linearity indeed reflects health and helps to keep patients in good health, we should be promoting nonlinear behavior. Studies have shown that frequent small interventions can keep a system that is prone to periodic behavior in nonlinearity.^32,33 Similarly, because nonlinear systems can display a spectrum of behaviors from periodic-to-self-organized behavior-to-chaotic dynamics depending upon their resources and interconnectedness, social systems exhibiting periodic behavior may move into nonlinearity in response to increased resources and decreased restraints,⁵ or to increased interconnectedness.³⁴

Perhaps we can train systems to maximize their variability. For example, exercise programs that used variable intensities and durations may promote a cardiovascular system capable of responding to whatever stressor comes along.

• For the patient above, the self-organized behavior is detrimental, producing over-reaction to stressors; a more chaotic mood pattern would minimize the impact of stressors. The best approach to achieve this may be to increase resources and decrease restraints. Thus, providing the patient with several ways of dealing with stress (ie, multiple treatment modalities including relaxation techniques, self-hypnosis, meditation, PRN anxiolytics) while promoting connectedness with others (ie, support groups, internet, church contacts, meditation) may increase chaotic variability.
• For the practitioner, self-organized behavior may explain the apparent random response to stress in patients. Such unstable behavior can be managed by providing multiple interventions simultaneously (ie, behavioral, pharmacological, social) or temporally (eg, frequent reinforcements of desired behavior) to encourage healthy nonlinearity.

Nonlinearity of primary versus specialty care

Do patients in primary care exhibit a different degree of nonlinearity than those seen in specialty care settings? Generally, yes. Mental illness, for instance, tends to be more severe among psychiatric patients than among primary care patients,^35-37 and CHF is more severe among cardiology patients.³⁸

Differences in severity of illness are important because, in some cases, the more severe the illness, the more periodic the dynamics.^9,39,40 Thus, the nonlinearity decreases as the severity increases. Because diseases exhibiting periodic dynamics should have a more predictable response to therapy, we would expect more severe illnesses to respond more predictably.⁴¹ This pattern has indeed been observed. Prognosis and predictability of treatment response is related to severity of illness in CHF, acute myocardial infarction, depression, and agoraphobia.^38,42-47

Thus, for both biomedical and psychosocial problems, predictability of treatment response correlates with the severity of illness. If patients seen in specialty settings have more severe disease, then we should expect that primary care patients exhibit more nonlinear behavior and are thus less predictable in their response.

Learning to see differently

Though trained to approach medical problems looking through “linear lenses,” we see nonlinear behavior all the time in our patients. If nonlinear processes represent health, then when systems are using healthy, nonlinear dynamics, they are resistant to disruptive external stressors. However, when such systems transition into periodicity due to illness, they may become predictable and more amenable to intervention, permitting physicians to treat them and hopefully restore the healthy, nonlinear dynamics.