Psilocybin-assisted Interpersonal Therapy for Depression

Study Design Interventional, Single arm, open label

1. Hypotheses:
2. It is feasible to deliver Psilocybin treatment integrated into interpersonal therapy for people with treatment resistant major depression (TRD).
3. It is feasible to recruit patients with TRD for this treatment in New Zealand.
4. Participants The study will recruit 20 participants who have a current diagnosis of Treatment resistant Major Depressive Disorder. The participants will need to agree to cease psychotropic medications including antidepressants as part of the preparation for psilocybin dosing.
5. Recruitment Participants will be recruited by referral from mental health services, primary care and community advertisements.
6. Screening

Screening involves a two-step process:

1. Participants will register their interest via a secure online Redcap website that will ask questions regarding initial eligibility. Those who pass the initial online screening and consent to further assessment of eligibility will be screened via telephone and review of online health records to determine whether they meet major inclusion/exclusion criteria, and thus whether they are eligible for an in-person screening session.
2. In-person screening will include a history and physical examination, ECG, a 30 cc blood draw for study measures and medical screening, a personal and family medical history questionnaire, psychiatric /psychological assessments and urine drug and pregnancy tests. These will be performed by clinical staff in the Clinical Research Unit (CRU, University of Otago, Christchurch Whatu Ora Waitaha).
3. Clinical assessment Psychiatric screening will be conducted by structured assessments Structured Clinical Interview for DSM Disorders (SCID), (mood and substance use sections) by the study team. After this screening potential participants will be clinically assessed by a consultant psychiatrist on the team, who will oversee participants care throughout the study and will liaise with the participants current health provider regarding the study, antidepressant discontinuation, clinical progress and any support required at the conclusion of the study. Psychoactive drug-use history, history of antidepressant treatments, and information about employment status and current functioning (including mood and psychological and psychosomatic symptoms) will be obtained.

Participants will be required to refrain from illicit drug use during the course of the study, and a urine test will be conducted before each psilocybin dosing session (e.g., testing for various opioids, stimulants and sedatives). Pregnant or nursing women are ineligible; female participants will receive a urine pregnancy test at intake and before each drug session and must agree to use effective methods of contraception during the study.

1. Informed consent process Written informed consent will be obtained at the Clinical Research Unit at the start of the in-person screening.
2. Intervention The study intervention is described in detail in the Interpersonal Therapy (IPT)+ Psilocybin Manual and is modified from Yale Manual for Psilocybin-assisted Therapy of Depression and Protocol for 'Effects of Psilocybin therapy for major depressive disorder: randomized clinical trial'. The intervention involves 8 sessions of psychotherapy and two doses of psilocybin over 10 weeks and one follow-up session at 18 weeks in the Clinical Research Unit, Dept of Psychological Medicine, University of Otago, Christchurch. During the study period (week 0-9) the participants will be under the care of the consultant psychiatrists and clinical team at the Clinical Research Unit, this includes the planned weekly contact as well as provision of urgent care during hours (via a duty clinician and psychiatrist), and the Crisis Resolution Team (CDHB) after hours.

Following screening and baseline measurements antidepressants will be gradually discontinued and Interpersonal Therapy (IPT) will be commenced in preparation for psilocybin dosing. Antidepressant discontinuation will follow clinical guidelines and will be supervised by consultant psychiatrist on the team, who will oversee participants care throughout the study. The discontinuation schedule is initial dropping of dose by half followed by tapering over 2-6 weeks. The 3 IPT preparation sessions are designed around the beginning phase of IPT (timeline of stressors and mood episodes, interpersonal inventory and identification of psychotherapy focus). The next sessions will involve psilocybin dosing and debriefing (2 psilocybin dosing sessions and 1 debriefing). This will be followed by 5 integration sessions of IPT. The IPT integration sessions will formulate the psilocybin experience within an IPT framework. IPT utilises emotional processing to facilitate change and it is anticipated this will be intensified in the psilocybin sessions.

Consultant psychiatrists will review each participant after completing psychotherapy to assess participants' ongoing treatment needs, including recommencing antidepressant medication if needed and referral to specialist mental health service if required.