Psilocybin for Treatment-Resistant Depression

Participant drop-out rates will be calculated to determine the feasibility of psilocybin in adults with treatment-resistant depression.

Feasibility will be judged based on change in Columbia Suicide Severity Rating Scale (CSSRS) scores. The CSSRS evaluates suicidal ideation and behaviour. The suicidal ideation score ranges from 0 (no ideation) to 5 (active suicidal ideation with specific plan and intent). Suicidal ideation intensity score ranges from 0 (no ideation) to 25 (most severe). The presence of suicidal behaviour is rated as a binary response; the lethality of actual attempts are rated on a scale of 0 (no or very minor physical damage) to 5 (death) and the potential lethality of actual attempts are rated on a scale of 0 (behaviour not likely to result in injury) to 2 (behaviour likely to result in death despite available medical care).

Feasibility will be judged based on the percentage of participants experiencing serious adverse events and the percentage of adverse events resolving within 48 hours of each dose administration.

The MADRS is a clinician-rated scale measuring depression severity, consisting of 10 items, each scored from 0 (normal) to 6 (severe), for a total possible score of 60; higher scores denote greater severity.

The proportion of participants with at least a 50% reduction in MADRS total score relative to baseline.

The proportion of participants with a MADRS total score of 10 or lower.

The MARRS was recently validated in adults with treatment-resistant major depressive or bipolar disorder receiving open-label intravenous ketamine at a community-based treatment center The MARRRS is a self-reported 14-item self-report measure of depressive symptoms present during the past 72 hours. Total score ranges from 0 to 42; a higher score indicates greater symptom severity.

The PHQ-9 is a self-rated measure of depressive symptom severity in the past two weeks. Each of the nine items is rated on a Likert scale, ranging from 0 (not at all) to 3 (nearly every day), and summed for a total score between 0 (no symptoms) to 27 (most severe).

The CGI severity module assesses the severity of a person's depressive illness using a seven-point Likert scale, ranging from "Normal, not at all depressed" to "Among the most extremely depressed patients". The CGI improvement module evaluates the global improvement of a person's condition since their last visit on a seven-point Likert scale, ranging from "Very much improved" to "Very much worse".

The QIDS-SR-16 total score ranges from 0 to 27 with 0 representing no depression and 27 representing severe depression.

The CSSRS evaluates suicidal ideation and behaviour. The suicidal ideation score ranges from 0 (no ideation) to 5 (active suicidal ideation with specific plan and intent). Suicidal ideation intensity score ranges from 0 (no ideation) to 25 (most severe). The presence of suicidal behaviour is rated as a binary response; the lethality of actual attempts are rated on a scale of 0 (no or very minor physical damage) to 5 (death) and the potential lethality of actual attempts are rated on a scale of 0 (behaviour not likely to result in injury) to 2 (behaviour likely to result in death despite available medical care).

Total scores on the 23-item CADSS range from 0 to 92; a higher score denotes greater dissociative symptom severity.

Total scores on the 6-item CADSS range from 0 to 24; a score of 3 or greater denotes the presence of dissociation symptom severity.

The BPRS rating scale has 18 items, each item rated on a severity scale of 1 (not present) to 7 (extremely severe). 0 is entered if the item is not assessed.

Total scores range from 0 to 60, with higher scores indicative of greater symptom severity.

The MEQ consists of 30 items, each item rated on a Likert scale (0-None/not at all to 5-Extreme, more than any other time in my life). The MEQ total score is computed by taking the average response to all items.

The SDS total score ranges from 0 to 30 with 0 representing no impairment and 30 representing severe impairment. The last two items of the scale (Days Lost and Days Unproductive) range from 0 to 7 (higher number denotes greater impairment).

The EQ-5D-5L consists of 5 items; each item ranges from 1 (no problems) to 5 (extreme problems). A participant's self-rated health is recorded on a vertical visual analogue scale (range 100 to 0), where the endpoints are labelled 'The best health you can imagine' (100) and 'The worst health you can imagine' (0).

The WHO-5 is a measure of overall well-being, rated on a scale of 0 to 25, with higher scores denoting higher quality of life.

The WPAI is a six-item self-administered rating scale measuring work absenteeism, presenteeism, and productivity loss and daily activity impairment. Individuals are asked to rate to what extent health problems affected their ability to do regular daily activities other than work at a job (0-No effect on daily activities to 10-Completely prevented me from doing my daily activities). Respondents who are currently employed are additionally asked to rate the number of hours missed from work due to health problems, the number of hours missed due to other reasons (e.g., vacation, time off to participate in this study), and the number of hours worked in the past seven days, as well as to what extent health problems affected productivity while working (0-No effect on my work to 10-Completely prevented me from working). Responses to each question are scaled to an overall percentage score (0 to 100), with higher values denoting greater impairment

The total score ranges from 0 to 20, with greater scores indicative of greater subjective cognitive impairment.

The DSST assesses relative contributions of speed, memory, executive function and visual scanning. Participants are required to copy symbols that are paired with simple geometric shapes or numbers within 90 seconds for a total possible score of 0 to 90. A higher score reflects greater performance.

The TMT is a two-part cognitive test. TMT-A assesses cognitive processing speed and consists of 25 circles distributed over a sheet of paper. Participants are asked to connect circles in numerical sequence. If a participant makes a mistake, the administrator points out the error, and the participant must return to the last correct circle and continue the task. Lower scores represent better performance.

The TMT is a two-part cognitive test. TMT-B assesses executive functioning and consists of 25 circles distributed over a sheet of paper. Participants are asked to connect circles in alternating numerical and alphabetical sequence (e.g., 1-A-2-B). If a participant makes a mistake, the administrator points out the error, and the participant must return to the last correct circle and continue the task. Lower scores represent better performance.

Total score ranges from 0 to 21; a higher score denotes greater symptom severity.

The SHAPS total score ranges from 14 to 56, wherein a higher score indicates greater hedonic capacity (lower anhedonic severity).

Inflammatory, neuroplasticity, and metabolic targets that are hypothesized to be relevant to the therpeutic mechanism of psilocybin in depression (e.g., interleukin-6, brain-derived neurotrophic factor, insulin, leptin).