Electrophysiologic Mechanisms of Ketamine Antidepressant Response

Phase 2Not Yet RecruitingNCT07768618

Emory University37 enrolled

Overview

This study aims to identify electrophysiologic biomarkers associated with antidepressant response to ketamine in adults with epilepsy undergoing clinically indicated stereo-electroencephalography (sEEG) monitoring who have at least mild depressive symptoms. Participants will receive a single subanesthetic intravenous ketamine infusion (0.5 mg/kg over 40 minutes) during their Epilepsy Monitoring Unit admission. Intracranial neural recordings and behavioral assessments will be collected before and approximately 24 hours after infusion to examine changes in neural circuits associated with rumination and anhedonia.

Depressive symptoms are common among individuals with epilepsy and are associated with reduced quality of life and poorer clinical outcomes. Although neuromodulation therapies have shown promise for treatment-resistant depression, the development of objective biomarkers to guide treatment remains a major challenge. Patients undergoing clinically indicated stereo-electroencephalography (sEEG) monitoring for epilepsy provide a unique opportunity to study human brain circuits with high spatial and temporal resolution. This prospective, single-site, open-label, within-subject mechanistic clinical trial will enroll adults with epilepsy undergoing inpatient sEEG monitoring who have at least mild depressive symptoms at baseline. Participants will receive a single intravenous ketamine infusion (0.5 mg/kg over 40 minutes) while hospitalized in the Epilepsy Monitoring Unit. Research assessments will be completed before infusion and approximately 24 hours afterward. The study examines candidate intracranial electrophysiologic measures of prefrontal-posterior midline connectivity and local cortical excitability, drawn from regions implicated in mood-relevant circuits. Behavioral and symptom measures include a task-based measure of thought content and a validated self-report measure of hedonic capacity. Investigators will test whether ketamine-induced neural changes correspond to changes in these behavioral and symptom measures. Additional exploratory analyses will examine whether acute effects during infusion predict delayed responses observed 24 hours later. All research procedures occur during routine clinical epilepsy monitoring, and no research-driven intracranial stimulation, surgery, imaging, or biospecimen collection is performed.

Study Type

INTERVENTIONAL

Allocation

Interventions

KetamineDRUG

Participants will receive one subanesthetic intravenous ketamine infusion administered at a dose of 0.5 mg/kg over 40 minutes during admission to the Epilepsy Monitoring Unit. The infusion will be supervised by a psychiatrist experienced in ketamine administration and conducted under continuous clinical monitoring. Intracranial sEEG recordings, behavioral assessments, and symptom measures collected before and approximately 24 hours after infusion will be used to evaluate electrophysiologic biomarkers associated with antidepressant response

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Admitted to the Emory EMU for clinically indicated sEEG monitoring for epilepsy. * At least mild depressive symptoms at baseline, defined as MADRS ≥7 or BDI-II ≥14. * Electrode coverage that includes midline regions sufficient for enrollment and analyses. * Ability to provide informed consent and to complete bedside tasks/questionnaires in English. * Expected to remain under inpatient monitoring through the planned \~24-hour post-infusion follow-up unless clinical needs dictate otherwise. Exclusion Criteria: * Documented IQ \<70, intellectual disability, severe cognitive impairment, delirium, severe aphasia, or other condition that prevents valid consent or task participation. * Current or past schizophrenia-spectrum disorder or other psychotic disorder. * Current manic/hypomanic episode or bipolar-spectrum illness judged by study psychiatrist/investigator to increase risk or confound interpretation. * Active alcohol or substance abuse/dependence within the past 3 months. * Imminent suicide risk or active suicidal intent requiring urgent intervention as determined by clinical assessment. Passive ideation without imminent intent may be considered on a case-by-case basis with psychiatric approval and enhanced monitoring. * Contraindication to subanesthetic ketamine, including uncontrolled hypertension, unstable cardiovascular disease, aneurysm/vascular malformation or similar condition conferring unacceptable risk, pregnancy, breastfeeding, or other clinically significant medical instability. * Clinical team determination that ketamine administration or study timing would interfere with epilepsy care or perioperative management. * Sedative or other medication exposure at a level that, in the judgment of the clinical team, precludes safe ketamine administration or reliable behavioral assessment (participant may be deferred rather than permanently excluded if the issue resolves).

Outcomes

Primary Outcomes

Change in Prefrontal-Posterior Brain Connectivity

This outcome measures intracranial electrophysiologic connectivity between prefrontal and posterior midline brain regions, calculated from gamma-band neural activity.

Time frame: Baseline and approximately 24 hours post-ketamine infusion

Change in Prefrontal Cortical Excitability Measure

This outcome measures local cortical excitability using a spectral measure derived from intracranial electrophysiologic recordings in prefrontal brain regions.

Time frame: Baseline (pre-infusion) and approximately 24 hours post-ketamine infusion.

Secondary Outcomes

Change in Thought Content Task Score

This outcome measures a task-based measure of the emotional content of participants' self-generated thoughts, reflecting positive versus negative thought bias.

Time frame: Baseline and approximately 24 hours post-ketamine infusion.

Association Between Change in Prefrontal-Posterior Brain Connectivity and Change in Thought Content Task Score

This outcome evaluates whether change in prefrontal-posterior brain connectivity is associated with change in the thought content task score.

Time frame: Baseline and approximately 24 hours post-ketamine infusion.

Change in Hedonic Capacity Score

This outcome measures a validated self-report measure of hedonic capacity, or the ability to experience pleasure.

Time frame: Baseline and approximately 24 hours post-ketamine infusion.

Association Between Change in Prefrontal Cortical Excitability and Change in Hedonic Capacity Score

This outcome evaluates whether a change in the prefrontal cortical excitability measure is associated with a change in the hedonic capacity score.

Time frame: Baseline and approximately 24 hours post-ketamine infusion.

Electrophysiologic Mechanisms of Ketamine Antidepressant Response

Overview

Conditions

Interventions

Eligibility

Locations (1)

Outcomes

Primary Outcomes

Secondary Outcomes

Central Contacts