Neurobiology of Treatment Responses in MDD

Volunteers will be randomized to receive placebo pills or a commercially available SNRI for 10 weeks. Volunteers will undergo imaging with structural and functional MRI and PET with \[11C\]carfentanil to determine baseline μOR BPND and changes in BPND measures during acute i.v. medication administration at the time of scanning before and after the 10-week treatment period. To elicit the activation of µ-opioid-mediated neurotransmission in the scanner, we utilize the introduction of medication (active or inactive) 1mL into an intravenous port every 4 minutes, 15 sec per infusion, starting 45 minutes after radiotracer administration, until scan completion. Participants are made aware that the study drug will be administered at the time a computer-generated human voice recording reads a second-by-second count of the infusion timing (15 sec).