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Zoe Doyle

University of Toronto, Toronto, Canada.

11 papers in the library · 179 citations · publishing 2023-2026

Papers

Psilocybin-assisted psychotherapy for treatment resistant depression: A randomized clinical trial evaluating repeated doses of psilocybin.

Med (New York, N.Y.) March 8, 2024 Joshua D Rosenblat, Shakila Meshkat, Zoe Doyle et al. 97 citations

Psilocybin-assisted psychotherapy (PAP) is feasible for patients with complex, treatment-resistant depression, including those with bipolar II disorder and baseline suicidality. In a randomized trial with 30 adults, those receiving immediate PAP showed greater reductions in depression severity (MADRS) compared to a waitlist control, with a large effect size (Hedge's g = 1.07). Adverse events were transient and no serious adverse events occurred. Repeated doses over six months were associated with further improvement. The findings suggest PAP can be safely delivered to this population and warrants further study.

Real world effectiveness of repeated ketamine infusions for treatment-resistant depression with comorbid borderline personality disorder.

Psychiatry Research March 5, 2023 Kevork Danayan, Noah Chisamore, Nelson B Rodrigues et al. 36 citations

Intravenous ketamine reduced symptoms of depression, borderline personality, suicidality, and anxiety in people with treatment-resistant depression and comorbid borderline personality disorder. In a retrospective analysis of 100 participants, those with borderline personality disorder showed significant improvement, with a reduction of 5.95 points on the Quick Inventory of Depressive Symptomatology and a reduction of 0.64 on the Borderline Symptom List. Both groups with and without borderline personality disorder improved similarly on depression, anxiety, and functionality measures, with no significant difference between groups.

Protocols and practices in psilocybin assisted psychotherapy for depression: A systematic review.

Journal of psychiatric research August 1, 2024 Noah Chisamore, Danica Johnson, Margery J Q Chen et al. 21 citations

Psilocybin-assisted psychotherapy shows promise for treating depression and distress in life-threatening illnesses, but a systematic review of 28 clinical trial protocols reveals substantial variability and inconsistency in therapeutic approaches beyond the basic framework of preparatory, dosing, and integration sessions. The review found no validated or universally agreed-upon protocol, with frequent lack of clarity in descriptions of therapy models, duration, and number of sessions. Future studies need to define and report psychotherapeutic components more clearly to identify the safest and most effective approaches.

Real-world effectiveness of repeated intravenous ketamine infusions for treatment-resistant depression in transitional age youth

Journal of Psychopharmacology May 16, 2023 Noah Chisamore, Kevork Danayan, Nelson B Rodrigues et al. 13 citations

Ketamine infusions led to clinically significant reductions in depression, anxiety, and suicidal thoughts in transitional age youth (ages 18–25) with treatment-resistant depression. In a retrospective analysis of 52 youth matched with a general adult sample (ages 30–60), both groups showed comparable improvements after four infusions over two weeks, with moderate effect sizes and no significant group differences. Adverse effects were mild and transient. The findings suggest ketamine is similarly effective and safe for younger adults as for older adults with treatment-resistant depression.

Psilocybin-Assisted Psychotherapy for Treatment-Resistant Depression in Bipolar II Disorder

Psychedelic Medicine November 18, 2024 Shakila Meshkat, Erica Kaczmarek, Zoe Doyle et al. 8 citations

In a small subgroup analysis of four adults with treatment-resistant depression associated with bipolar II disorder, two 25 mg doses of psilocybin combined with psychotherapy were associated with reductions in depressive symptoms. The average depression score on the Montgomery–Åsberg Depression Rating Scale dropped from 32.5 at baseline to 20.3 two weeks after the first dose, and to 19 two weeks after the second dose; at six months the average score was 21.3. Mania ratings remained stable, and no mania, hypomania, or psychosis occurred. The authors suggest psilocybin may improve depressive symptoms in bipolar II disorder but call for larger studies to confirm the findings.

Examining mystical experiences as a predictor of psilocybin-assisted psychotherapy for treatment-resistant depression

Journal of Psychopharmacology July 1, 2025 Ryan M Brudner, Erica Kaczmarek, Marc G Blainey et al. 3 citations

In a small sample of 31 individuals with treatment-resistant major depressive disorder or bipolar II disorder, those who reported more intense mystical experiences after their first dose of psilocybin-assisted psychotherapy showed greater reductions in depressive symptoms two weeks later. This link between mystical experiences and antidepressant benefit was not observed after the second or third psilocybin doses. The findings offer preliminary support for the idea that mystical-type experiences play a therapeutic role in psilocybin-assisted psychotherapy, extending prior work to a clinically complex population with treatment-resistant depression.

Comparing Antidepressant Effects of Psilocybin-Assisted Psychotherapy in Individuals That Were Unmedicated at Initial Screening Versus Individuals Discontinuing Medications for Study Participation: Comparaison des effets antidépresseurs de la psychothérapie assistée par la psilocybine (PAP) chez les personnes non médicamentées à la sélection initiale et les personnes ayant arrêté les médicaments pour participer à l’étude

The Canadian Journal of Psychiatry March 25, 2025 Noah Chisamore, Erica S Kaczmarek, Zoe Doyle et al. 1 citation

A single 25 mg dose of psilocybin combined with psychotherapy produced clinically significant reductions in depression, anxiety, and suicidality symptoms over two months in people with treatment-resistant depression. Among 27 participants, those who tapered off antidepressant medications before treatment (n = 18) and those not on antidepressants at screening (n = 9) showed comparable improvements, with no significant differences between groups on clinician-rated depression, self-reported depression, anxiety, or suicidality. The intensity of the psychedelic experience was also similar. These results suggest that tapering antidepressants before psilocybin-assisted psychotherapy may not diminish therapeutic benefits, though further research is needed.

Intranasal Ketamine for Existential Distress in Advanced Cancer.

Journal of pain and symptom management August 1, 2026 Stefan Aguiar, Mary Makarious, Orly Lipsitz et al.

In adults with advanced cancer receiving palliative care, intranasal ketamine was associated with clinically meaningful improvements in existential distress, anxiety, symptom burden, and quality of life. Fifteen participants who completed three doses of ketamine showed improvements exceeding established minimal clinically important differences on measures of anxiety, death and dying distress, overall symptoms, and quality of life. Improvements in existential well-being were larger than those in physical symptoms. Changes in depression did not significantly correlate with changes in existential distress outcomes, suggesting ketamine may have independent effects on multiple dimensions of distress in this population.

Examining the effects of psilocybin-assisted psychotherapy on anhedonia in treatment-resistant depression

Journal of Affective Disorders February 12, 2026 Erica Kaczmarek, Nelson Rodriguez, Noah Chisamore et al.

Anhedonia, a core symptom of depression that often resists standard treatments, may be reduced by psilocybin-assisted psychotherapy (PAP). In a secondary analysis of a randomized, waitlist-controlled trial, 30 adults with treatment-resistant depression (major depressive disorder or bipolar II disorder) received one 25 mg dose of oral psilocybin plus psychotherapy. Anhedonia severity, measured by the Snaith-Hamilton Pleasure Scale, decreased significantly at the 2-week primary endpoint, with clinically meaningful improvements persisting at 3 and 6 months. The analysis adjusted for sex and age. These preliminary results suggest PAP could be a promising intervention for anhedonia in treatment-resistant depression, though larger placebo-controlled trials are needed to confirm the findings and clarify underlying mechanisms.

Cognitive outcomes following psilocybin-assisted therapy in treatment-resistant depression: A post-hoc analysis of a randomized, waitlist-controlled trial

Progress in Neuro-Psychopharmacology and Biological Psychiatry November 22, 2025 Shakila Meshkat, Noah Chisamore, Zoe Doyle et al.

A single dose of psilocybin was linked to small, temporary gains in processing speed and executive function in people with treatment-resistant depression. These cognitive improvements seemed unrelated to mood changes but did not consistently surpass the improvements expected from simply retaking the tests. The findings underscore the need for larger, controlled studies to determine whether psilocybin genuinely enhances cognition or if the observed changes stem from practice effects or mood shifts.

Examining the impact of comorbid posttraumatic stress disorder on ketamine's real-world effectiveness in treatment-resistant depression.

European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology February 1, 2025 Danica E Johnson, Nelson B Rodrigues, Sydney Weisz et al.

Depression with co-occurring posttraumatic stress disorder (PTSD) leads to more severe symptoms and poorer response to standard treatments. In a retrospective analysis of 134 patients with treatment-resistant depression, four ketamine infusions (0.5-0.75 mg/kg) reduced depressive symptoms equally in those with and without comorbid PTSD; no significant group-by-time interaction was found. PTSD symptoms also significantly improved across all symptom clusters, with moderate to large effect sizes. Ketamine shows promise as an effective intervention for this hard-to-treat population, though future randomized trials should explore factors driving improvement and long-term outcomes.