Exploring New Electroencephalogram Parameters in Electroconvulsive Therapy

Abstract

Background

Electroconvulsive therapy (ECT) is an effective treatment against severe depressive episodes, which has been shown to induce volume changes in the hippocampus. The power spectrum of the electroencephalogram (EEG) follows a characteristic power-law relation, but its utility as a metric of ECT-induced seizures has not been explored. Objective

This pilot study aims to evaluate a novel metric based on the power spectrum of the EEG recordings from ECT-induced seizures—its association to volume changes in the hippocampus after ECT and improvement in depression rating scores. Methods

Depressed patients treated with ECT underwent brain magnetic resonance imaging before and after treatment and the EEG from each seizure was recorded (N = 29). Hippocampal volume changes and EEG parameters were recorded in addition to clinician-rated and self-reported measures of depressive symptoms. The slope of the power law in the power spectral density of the EEG was calculated. Multivariate linear models relating seizure parameters to volume change or clinical outcome were systematically and successively simplified. The best models were selected according to Akaike information criterion. Results

The slope of the power law was steeper in the right than the left hemisphere (P < 0.001). Electroencephalogram measures were included in the best models of volume change for both hippocampi as well as in the models explaining clinical outcome (P = 0.014, P = 0.004). Conclusions

In this pilot study, novel EEG measures were explored and contributed in models explaining the variation in volume change in the hippocampus and in clinical outcome after ECT.