Effects of noise on different disease states of recurrent affective disorders

Background: Nonlinear dynamics ale current ly proposed to explain the cours e of recurrent affective disorders. Such a nonlinear disease model predicts complex interactions with stochastic influences, in particular, because bo th disease dynamics and stochastic influences, such as psychosocial stresso rs, will vary during the course of the disease. Ne approach this problem by investigating general effects of noise intensity on different disease stat es of a nonlinear model for recurrent affective disorders. Methods: A recently developed neurodynamic model is studied numerically. Results: Noise can cause unstructured randomness ol can maximise periodic o rder. The frequency of episode occurrence can increase with noise but it ca n also remain unaffected or even cart decrease. The observed effects, there by depend critically on both the noise intensity and the internal nonlinear dynamics of the disease model. Conclusions: Our findings indicate that altered stochastic influences can s ignificantly affect the outcome of a dynamic disease. To evaluate the effec ts of noise, it is essential to know about rite underlying dynamics of resp ective disease states. Therefore, characterization of low-dimensional dynam ics might became valuable for disease prediction and control, (C) 2000 Soci ety of Biological Psychiatry.