CET-REM (Correlating ECT Response to EEG Markers)

Electroconvulsive therapy (ECT) is an effective treatment for many psychiatric illnesses, including major depressive disorder. While effective, objective markers have not been developed to predict clinical outcome trajectories following ECT. This is important given the risks and costs incurred during a full treatment course. Electroencephalography (EEG) is typically employed to monitor the generation and termination of ECT-induced seizures but leverage of markers toward prognostication remains a future goal. The investigators have characterized two distinct EEG patterns associated with ECT-induced generalized seizures and have two sleep markers that may serve as markers for predicting response to treatment. Central Positive Complexes (CPCs) are large ictal complexes with a scalp topology of voltage declining from the top of the head. CPCs are localized to cortical areas that are involved in the formation of sleep spindles and slow wave sleep. A pattern of low-voltage activity, known as post-ictal generalized electroencephalographic suppression (PGES), is frequently used to document termination of these seizures. Additionally, two EEG markers of sleep microstructure may have utility given their association with synaptic plasticity, a process presumably invoked over the course of ECT-induced recovery from psychiatric illness as pathologic neural circuitry undergoes reconfiguration. These two markers, sleep spindles and slow waves show altered expression patterns in patients with psychiatric disorders, and thus may be useful as objective markers of ECT responsiveness. None of the above EEG markers have been explored for an association to interval changes in disease severity over the course of ECT. This project will incisively probe the relationships between temporal trajectories of major depressive disorder severity and longitudinal measurements of ictal and postictal EEG markers.