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S087-3

Assessment of Neurophysiological Changes with Electroconvulsive Therapy in
Mental Disorders Using Nonlinear Approach

Ryoko Okazaki

Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, Japan

Background/Objective: The exact neurophysiological mechanism of electroconvulsive therapy
(ECT) remains elusive. Results of previous neurophysiological studies support the hypothesis that
aberrant functional connectivity underlies the pathophysiology of mental disorders, which engenders
abnormal electroencephalogram (EEG) complexity.

Method: Recently developed multiscale entropy analysis, which has underpinned aberrant functional
connectivity in mental disorders, was introduced to explore changes in EEG complexity occurring
with ECT in three patients with depression and an ASD patient with catatonic OCD.

Result: All patients demonstrated a decrease in EEG complexity in the frontal region, especially at
higher frequencies. This decrease was associated with clinical improvement. Additionally, ASD
patient expressed an increase at lower temporal scales in the occipital region. Furthermore, these
changes in ASD patient were associated with the elevation of brain-derived neurotrophic factor.

Conclusion: The changes in EEG complexity with ECT might be a result of amelioration of
functional connectivity in the brain of mental disorders. Multiscale entropy analysis might be a
useful analytical method to elucidate neurophysiological mechanisms and evaluate the therapeutic
efficacy of ECT.