Added Value of a Neuroendocrine Test Battery in the Response to Repetitive Transcranial Magnetic Stimulation (rTMS) Treatment

This study is exploring whether a set of hormone and brain chemistry tests — measuring things like cortisol and other stress-related biological markers — can predict how well a patient with severe depression will respond to repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation treatment. **You may be eligible if...** - You are between 18 and 65 years old - You have a diagnosed depressive episode based on DSM-5 criteria - You are currently hospitalized and have not responded adequately to at least two antidepressant treatments - You are scheduled to receive rTMS as part of your care **You may NOT be eligible if...** - You have a pacemaker or metal implants in your skull that make rTMS unsafe - You have a history of epilepsy or seizures - You have a primary diagnosis of bipolar disorder or psychotic disorder - You are pregnant - You have substance use disorder Talk to your doctor to see if this trial is right for you.