Abstrakt
Background: According to recent findings cognitive and emotional dysregulation in depression and psychiatric disorders may be related to deficits in inhibitory functions and temporo-limbic seizure-like activity due to specific changes in neural dynamics and complexity of neural networks. Methods: In order to evaluate the clinical utility of nonlinear analysis of EEG complexity (measured by Lyapunov exponents) and to assess underlying epileptiform changes, we studied a sample of 19 depressive patients including nine depressive patients with episodic sharp-wave EEG abnormalities and ten depressive patients without any abnormalities, and compared also subgroups of these patients who used benzodiazepine medication to assess its influence on EEG complexity.
Results and findings: The results show that the depressive patients with episodic sharp-wave EEG abnormalities had significantly lower EEG complexity than the control groups of patients. The data also indicate that benzodiazepines significantly influence neural complexity and increase it in the subgroup of patients with sharp wave abnormalities, and on the other hand decrease the level of complexity in the control subgroup of depressive patients.
Conclusions: In agreement with other findings results of this study suggest that sharp waves or other underlying epileptiform EEG abnormalities related to abnormal neural excitability and disturbances in brain inhibitory systems may be reflected in specific changes of EEG complexity. These specific changes in EEG complexity may be related to treatment resistance to usual medications in several depressive patients and might represent clinical indicators for anticonvulsant treatment.