Pharmacologic Augmentation of TMS for Depression with D-serine

Subjects will either receive iTBS using a Magventure TMS device or 18-Hz H1 TMS using a dTMS Brainsway device plus placebo.

"D-serine, 80 mg/kg, oral administration, will be advised to be taken 1-hour prior rTMS treatment day (Mon-Fri) for 6 weeks. Dosing is based on maximal plasticity at 80 mg/kg, and clinical dose-finding studies demonstrating that doses between 60 - 120 mg/kg were superior in clinical effectiveness to 30 mg/kg and were safe.~Subjects will not be randomized into their TMS group and will either receive iTBS using a Magventure TMS device or 18-Hz H1 TMS using a dTMS Brainsway device. Subjects will have their TMS protocol/treatment determined at the time of consultation according to clinical appropriateness as is the standard of care at the TMS clinic at McLean Hospital."