Invited Symposium: Nonlinear Dynamical Systems in Psychiatry
Discussion and Conclusion
The major observation of our study concerns the co-evolution of the global entropy and of the first component scores with mood variations along patients' treatment. Moreover, raw entropy maps depict comparable patterns for similar self-assessment scores in each patient. Such results strongly suggest that mood can be considered as a phenomenon emerging from the global interactions in brain activity as revealed by dynamical methods. The changes in the first component scores, along treatment, can be related to the existence of a bifurcation in brain dynamics concomitant with mood modulation. This is particularly illustrated by Mrs. R.'s ECT treatment where a clear drop in her mood level is associated with a drastic change in the entropy level (ref. 4). Nevertheless, in pharmacological treatments, the bifurcations are less abrupt and seem to lead to less stable states than in the case of ECT. The existence of bifurcations processes in brain dynamics associated with the changes in the patients' clinical state leads to reconsider the debate between state and traits in depression. We have shown that brain dynamics is not a constant trait of the pathology but rather the sign of a particular state. The clinical improvement would thus be a bifurcation from the depressed brain dynamics towards a new state. We reported a longitudinal co-variation between brain dynamics complexity and mood, during different treatments of depressed patients. Whatever the therapeutic strategy used, the brain dynamics' evolution is similar for all patients and reveals a common way of recovery. These results emphasis and demonstrate the potential use of EEG dynamical methods for the clinical follow up of psychiatric treatments.
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|Thomasson, N; (1998). Brain Dynamics Bifurcation and Remission of Depressive Episode. Presented at INABIS '98 - 5th Internet World Congress on Biomedical Sciences at McMaster University, Canada, Dec 7-16th. Invited Symposium. Available at URL http://www.mcmaster.ca/inabis98/sulis/thomasson0507/index.html|
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