CET- REM (Correlating ECT Response to EEG Markers)

Correlating Electroconvulsive Therapy Response to Electroencephalographic Ictal Complexes and Postictal Markers

Single-center study to determine the relationship between changes in depression symptoms and electroencephalographic (EEG) patterns induced by electroconvulsive therapy (ECT)

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. Ninety patients will be followed for up to 22 ECT sessions. Bedside clinical instruments will allow assessments of depression severity. High-density (65-electrode) EEG caps will be acquired before and up to 30 minutes following ECT electrical stimulation. Duration of CPCs will be determined using a novel automated algorithm. Duration of PGES will be evaluated using recently validated automated algorithms. Wireless wearable devices will address previous barriers to the longitudinal study of sleep microstructure in the outpatient ECT setting. Slow wave activity and density of sleep spindles will be evaluated at the first cycle of N3 and N2 sleep, respectively. For a subset of patients, feasibility will be assessed for the potentiation of slow wave activity through closed loop acoustic stimulation.

EEG on nights after ECT session will be recorded using the DREEM device. Sleep EEG data will also be acquired for a minimum of one night prior to the first ECT session, providing a true baseline measure. The DREEM device allows continuous recording of multichannel EEG

Closed loop acoustic stimulation will be enabled on the DREEM headband on a subset of study participants. The device delivers stimulation in phase with the upstroke of the EEG slow wave (STIM) to boost slow oscillation activity. The timing of this stimulus augments the expression of subsequent slow waves.

The Quick Inventory of Depressive Symptomatology-Self Report (QIDS-SR16) is a measure of depression symptom severity that has been validated for clinical and research use53. It is a standard self-report measurement completed by patients prior to each ECT session

A high-density 65-electrode EEG scalp electrode net (EGI/Philips) with Elefix conductive gel injected within Ag/AgCl electrode sensors is utilized to monitor brain activity during the ictal period

A board-certified epileptologist will review all seizures to assess seizure parameters, including duration of seizure and interval of PGES. Preprocessing of the PGES periods will be accomplished with band-pass filtering from 2 to 30 Hz with 1st order Butterworth filters.

Following EEG preprocessing of DREEM sleep recordings, SWA will be quantified using a custom-written MATLAB module as the average of total power spectral estimates within the 0.5-4 Hz frequency band in one minute intervals, during the first cycle of N3 sleep.

Interval change in Quick Inventory of Depressive Symptomatology-16 Item Self Report (QIDS-SR16) between ECT sessions.

16 item Self-report questionnaire that best describes the participant's depressive symptoms over the last seven days. Scale: 0=never or do not, 3=nearly all the time, or the highest level of time listed on the question.

Questions relating to usual sleep habits during the past month. The first four questions are free text entry and indicate the patient's sleep experience for the majority of days and nights in the past month. The remaining questions are on a scale with 1=not during the past month, 2=less than once a week, 3=Once or twice a week, 4=Three or more times a week

Total time (in seconds) during the ictal period for which CPCs are present in the EEG immediately following seizure induction until termination of the seizure. Range of values: 0 - 300 seconds

Total time (in seconds) during the postictal period for which PGES is present in the EEG immediately following seizure termination for up to 5 minutes. Range of values: 0 - 300 seconds

Median rectified EEG amplitude (in microvolt) during the postictal period for which PGES is present in the EEG immediately following seizure termination for up to 5 minutes. Range of values: 0 - 10 microvolt

Density of EEG sleep spindles during first cycle of non-rapid eye movement (NREM) stages N2 on evenings following ECT treatments.

The total number of EEG sleep spindles per minute present during the first identified cycle of N2 sleep. Range of values: 0 - 60 spindles/min

Total power of EEG slow waves per minute present during the first identified cycle of N3 sleep Range of values: 0 - 50 dB/min

Inclusion Criteria: Age 18 years or greater Referral for ECT index course for treatment-resistant depression (unipolar major depressive disorder or bipolar depression), major depressive disorder with psychotic symptoms, schizophrenia or schizoaffective being treated for a depressed episode, unspecified depression Exclusion Criteria: Schizophrenia or schizoaffective disorder not being treated for a depressed episode.

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