Long Term Follow Up KET-PD

This is a roll-out study from the ongoing clinical trial (KET-PD trial; NCT04944017, HIC 2000030394). We will adopt an implementation science approach to have participants across ketamine and placebo groups in one of two arms: a) follow-up with treatment as usual (TAU) (at 3 and 6 months post-infusions); b) follow-up with 3 months of Cognitive Behavior Therapy (CBT) post-infusions, delivered remotely once per week, with follow-up assessments at 3 and 6 month timepoints. CBT is expected to have a superior sustained antidepressant response to the TAU follow-up group in both ketamine and placebo arms. We hypothesize that ketamine + CBT will show the most superior antidepressant response at follow-up.