NMDA Modulation in Major Depressive Disorder

This study is investigating how brain chemicals — specifically a system involving NMDA receptors — are involved in major depression. Researchers are testing treatments that work on this pathway, which is different from traditional antidepressants (SSRIs), to find new options for people whose depression has not responded to standard medications. **You may be eligible if...** - You have a diagnosis of major depressive disorder (MDD) - Your depression is currently severe (Hamilton rating scale score of 18 or higher) - You have been off antidepressant medications for at least 2 weeks - You are willing to participate and can give informed consent **You may NOT be eligible if...** - You have bipolar disorder, schizophrenia, or another psychotic disorder - You have a history of drug or alcohol abuse in the past 6 months - You have epilepsy, a history of stroke or serious brain injury - You are at moderate-to-severe risk of suicide - You have not responded to two or more different types of antidepressants in the past (treatment-resistant depression) - You have previously had electroconvulsive therapy (ECT) - You recently started or changed psychotherapy Talk to your doctor to see if this trial is right for you.