Flumazenil for Benzodiazepine Reversal in Electroconvulsive Therapy

The study will include adult inpatients (≥18 years of age) diagnosed with a mood disorder (major depressive disorder or bipolar disorder), currently experiencing a depressive episode (ICD-10: F31.3-5, F32 or F33), who are deemed eligible for ECT by a treating psychiatrist who is not affiliated with the study. Based on a power analysis, 132 participants (66 per group) are required to achieve adequate statistical power. To account for an anticipated 10% dropout rate from baseline to follow-up, the investigators will recruit 145 participants. Recruitment will be carried out through psychiatric hospital wards within the Mental Health Services of the Capital Region of Denmark.

Participants will be randomized following an initial screening to confirm eligibility. Randomization will be conducted using the automated randomization module in the Research Electronic Data Capture (REDCap) system, based on a pre-generated randomization list with variable block sizes of two and four. Allocation will be stratified by age (< 60 or ≥ 60 years) and electrode placement (unilateral vs. bilateral). Randomization will occur no later than the day prior to the second ECT session of the treatment series. Primary outcome assessors are blinded to the group allocation.

Baseline assessments will be conducted the day before the first ECT session or, if not otherwise possible, the day before the second ECT session. Participants will complete a brief neuropsychological assessment comprising the Screen for Cognitive Impairment in Psychiatry (SCIP) and additional measures of executive functioning and autobiographical memory. Participants will also complete self-report questionnaires assessing subjective cognitive complaints. Depressive symptom severity will be rated using the Hamilton Depression Rating Scale (HDRS).

During the ECT treatment series, repeated assessments will be conducted for each session. Participants will provide self-reported ratings of pre-treatment anxiety shortly before the session, while clinicians will record measures of seizure architecture, and time to reorientation following the session.

Follow-up assessments will be conducted 3-7 days after completion of the ECT-series, which serves as the primary end point. At follow-up, the brief neuropsychological assessment, self-report questionnaires, and HDRS ratings will be repeated. Participants will also complete a short self-report questionnaire of their treatment satisfaction. Structural and functional magnetic resonance imaging (MRI) is conducted within the 3-7 days after completion of the ECT series, coinciding with the follow-up assessment.

Inclusion criteria

• Current depressive episode (unipolar or bipolar), corresponding to ICD-10 codes F31.3-5, F32 or F33.
• Admitted at a study affiliated department in the Mental Health Services of the Capital Region of Denmark
• Referred to ECT by the regular psychiatrist and has given consent to ECT
• Currently receiving treatment with a benzodiazepine and/or zopiclone, at a minimum daily dose equivalent to 0.5 mg lorazepam.

Exclusion criteria

• Involuntary treatment with ECT
• Known gross abnormalities in brain structure deemed likely to influence cognitive functioning
• Pregnancy or breast-feeding
• Inability to read or understand Danish
• Acute organic brain disease (e.g., delirium) influencing the ability to give informed consent
• Any pre-existing condition associated with an increased risk of prolonged or uncontrollable seizures, including but not limited to epilepsy or alcohol- or benzodiazepine withdrawal states
• Conditions associated with reduced metabolism of flumazenil (e.g., liver failure)