Visit 6: After the participants have completed their medication course on the morning of this visit day, they will return to have cognition and mood reassessed. Vital signs will be taken and blood will be drawn to assess CMP, CBC, cortisol and phenytoin levels. Participants will now enter a "washout" period of this medicine combination (approximately 3 weeks) before returning for their final visit. For those participants offered the MRI scans, their visit will extend to approximately 3 hours.