Gamma Oscillations as a Prognostic Marker for Ketamine Therapy in Treatment Resistant Depression

This study uses brain wave recordings (EEG) to examine whether a specific pattern of brain activity (gamma oscillations at 40 Hz) before or during ketamine treatment can predict who will respond to it — targeting patients with treatment-resistant depression (TRD), meaning their depression has not improved with standard antidepressants. **You may be eligible if...** - You are between 21 and 45 years old - You have a confirmed diagnosis of major depressive disorder that has not responded adequately to multiple antidepressant treatments - You are considered a candidate for ketamine therapy by your doctor - You are able to understand and consent to all study procedures **You may NOT be eligible if...** - You have bipolar disorder, active psychosis, or significant substance use disorder - You have medical conditions that make ketamine administration unsafe (e.g., uncontrolled blood pressure, certain heart conditions) - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.