Consequences of deterministic and random dynamics for the course of affective disorders.
BACKGROUND
Uni- and bipolar affective disorders tend to be recurrent and progressive. Illness patterns can evolve from isolated episodes to more rapid, rhythmic, and "chaotic" mood patterns. Nonlinear deterministic dynamics are currently proposed to explain this progression. However, most natural systems are nonlinear and noisy, and cooperative behavior of possible clinical relevance can result.


METHODS
The latter issue has been studied with a mathematical model for progression of disease patterns in affective disorders.


RESULTS
Deterministic dynamics can reproduce a progression from stable, to periodic, to chaotic patterns. Noise increases the spectrum of dynamic behaviors, enhances the responsiveness to weak activations, and facilitates the occurrence of aperiodic patterns.


CONCLUSIONS
Noise might amplify subclinical vulnerabilities into disease onset and could induce transitions to rapid-changing dysrhythmic mood patterns. We suggest that noise-mediated cooperative behavior, including stochastic resonance, should be considered in appropriate models for affective illness.
Department of Psychiatry and Psychotherapy, University of Marburg, Germany.
M T
MT
Huber
H A
HA
Braun
J C
JC
Krieg
D018450:Disease Progression; D006801:Humans; D007696:Kindling, Neurologic / Q000502:physiology; D008137:Longitudinal Studies; D008954:Models, Biological; D019964:Mood Disorders / Q000175:diagnosis*; D009622:Noise / Q000009:adverse effects; D017711:Nonlinear Dynamics; D010507:Periodicity; D013269:Stochastic Processes