Ketamine administered biomedically or as psychedelic-assisted therapy in treatment-resistant depression: Differing efficacy based on depressive subtype or presence of childhood trauma?

ObjectiveThe ideas presented in this paper are based on a presentation at a festschrift event marking the retirement of Professor Gordon Parker from UNSW, Sydney. Drawing on Gordon's depressive subtyping approach and his critiques of a unitary view of major depressive disorder and treatment-resistant depression (TRD), we aim to (i) explore differing models of ketamine for TRD - biomedical versus 'psychedelic-assisted' therapy, and (ii) whether there may be differential efficacy in each approach based on subtype and/or childhood trauma.ConclusionPreliminary results from our study indicate in an open-label (but not randomised controlled) setting, biomedical ketamine may be superior in melancholic versus non-melancholic depression subtyped using Sydney Melancholia Prototypic Index. Studies of ketamine as a psychedelic agent combined with psychotherapy are lacking. We outline an empirical approach to determine whether ketamine with integrated psychotherapy has differential efficacy based on depressive subtype or past childhood trauma.