This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Psilocybin Therapy for Depression and Anxiety in Parkinson's Disease (NCT04932434), a na phase 2 study. The primary outcome is Movement Disorder Society-sponsored Revision of Unified Parkinson's Disease Rating Scale (MDS-UPDRS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04932434 |
| Phase | Phase 2 |
| Condition | Parkinson Disease, Depression, Anxiety |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Joshua Woolley, MD, PhD |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with Parkinson's disease and depression or anxiety. The registry record lists Parkinson disease, depression, and anxiety as conditions and gives an enrollment of 12. Detailed eligibility criteria and further description of the enrolled population are not reported in the registry record.
Intervention
The intervention is psilocybin therapy. The registry describes one or two doses in a monitored setting, approximately two weeks apart, alongside preparation sessions before dosing and integration sessions afterward. The registry record does not report how many participants received each dosing schedule.
Comparator
This is a single-group study with no comparator group listed. Allocation is recorded as not applicable and masking as none. The study therefore does not directly compare psilocybin therapy with a control condition or another treatment.
Primary question
The primary outcome is the Movement Disorder Society-sponsored Revision of the Unified Parkinson's Disease Rating Scale, or MDS-UPDRS, total score. It measures Parkinson's disease symptom severity. The record specifies assessments 7 days after the first drug dose and 7 and 30 days after the second drug dose. It describes the study purpose as assessing safety, tolerability, and feasibility of psilocybin therapy for depression and anxiety in people with Parkinson's disease. Numerical primary-outcome results are not reported in the registry record.
3. Trial Design
The registry identifies NCT04932434 as a Phase 2 pilot study, titled Psilocybin Therapy for Depression and Anxiety in Parkinson's Disease. Its status is completed. The listed enrollment is 12. The record gives a start date of 2021-08-15 and a primary completion date of 2024-12-31.
The design is single-group, with allocation marked not applicable and masking marked none. There is no concurrent control arm in the registry record. Consequently, the study is organized to describe participants receiving psilocybin therapy rather than to estimate a randomized difference between treatment groups. Changes observed over time, if reported, would need to be interpreted within that design rather than as a direct comparison with an untreated or alternative-treatment group.
The intervention description says participants will receive one or two psilocybin doses in a monitored setting approximately two weeks apart. Preparation sessions are described before dosing and integration sessions afterward. The record does not specify the actual distribution of participants across the one-dose and two-dose schedules or give further details about the session content.
The stated study purpose is to determine safety, tolerability, and feasibility for people with Parkinson's disease and depression or anxiety. The primary outcome listed is the MDS-UPDRS total score, a clinician-administered measure of Parkinson's disease symptom severity. Assessments are scheduled at 7 days after the first drug dose, and at 7 and 30 days after the second drug dose. The first drug dose is described as occurring 2-4 weeks after enrollment; the second is described as occurring 2 weeks after the first dose, or 4-6 weeks after enrollment.
These registry entries establish the planned structure and measurement schedule, not the results. Numerical primary-outcome findings and the analysis population are not reported in the registry record. Further protocol details, including a statistical analysis plan and the rationale for the enrollment target, are also not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Psilocybin Therapy |
|---|---|
| STARTED | 12 |
| COMPLETED | 12 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: At 7 days following the first study drug administration, incomplete data was recorded for this assessment for one participant, such that total scores were not available for the full analysis population. The data entry error leading to this missing data has been determined to be an inevitable byproduct of the natural course of the research process, with no specific cause identified.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Psilocybin Therapy |
|---|---|---|
| Participants analysed | 12 | |
| Age, Continuous | Years | 63.2 (SD 8.2) |
| Sex: Female, Male: Female | Participants | 5 |
| Sex: Female, Male: Male | Participants | 7 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 12 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Movement Disorder Society-sponsored revision of Unified Parkinson's Disease Rating Scale (MDS-UPDRS) | Total score | 76.333 (SD 21.652) |
| Columbia Suicide Severity Rating Scale (C-SSRS) | Total score | 1.083 (SD 1.24) |
| Enhanced Scale for the Assessment of Positive Symptoms for Parkinson's Disease (eSAPS-PD) | Total score | 2.333 (SD 3.525) |
| Psychosis and Hallucinations in Parkinson's Disease Questionnaire (PsycH-Q) | Total score | 3.25 (SD 5.172) |
| Neuropsychiatric Inventory Caregiver Distress Questionnaire (NPI-Q): Severity | Total score | 6.75 (SD 3.911) |
| Neuropsychiatric Inventory Caregiver Distress Questionnaire (NPI-Q): Distress | Total score | 7.667 (SD 5.228) |
| Montgomery-Asberg Depression Rating Scale (MADRS) | Total score | 21 (SD 8.666) |
| Hamilton Anxiety Rating Scale (HAM-A) | Total score | 16.667 (SD 3.725) |
| Probabilistic Reversal Learning task (PRL) | Number of successful reversals | 2.889 (SD 1.364) |
| Cognitive Control and Flexibility Questionnaire (CCFQ) | Total score | 69.25 (SD 10.341) |
| Quality of Life in Neurological Disorders (NeuroQoL) - Fatigue | Total score | 28.333 (SD 3.725) |
| Quality of Life in Neurological Disorders (NeuroQoL) - Cognitive Function | Total score | 24.917 (SD 6.374) |
6. Primary Endpoint
The registry lists the primary outcome as Movement Disorder Society-sponsored Revision of Unified Parkinson's Disease Rating Scale (MDS-UPDRS), measured over 7 days after first drug dose (which takes place 2-4 weeks after enrollment); 7 and 30 days after second drug dose (which takes place 2 weeks after first drug dose, i.e., 4-6 weeks after enrollment).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Total score |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the MDS-UPDRS total score. It is a clinician-administered assessment intended to measure the severity of Parkinson's disease symptoms. The instrument covers non-motor experiences of daily living, motor experiences of daily living, motor examination, and motor complications. The record states that all 65 items are rated on a 5-point scale from 0-4 and that the total score is calculated by summing item scores. Higher scores indicate more severe Parkinson's disease symptoms.
A clinician-administered scale provides a structured way to assess symptoms across several domains rather than relying on a single symptom question. Repeated assessment can describe how scores vary across the specified post-dose time points. In a single-group study, such measurements can characterize changes within the enrolled group, but they do not by themselves distinguish an intervention effect from other explanations for change over time.
The registry lists the endpoint as a mean with standard deviation and specifies the assessment schedule: 7 days after the first drug dose, then 7 and 30 days after the second drug dose. The first of these time points has a documented missing total score for one participant. Numerical means, standard deviations, and other primary-outcome results are not reported in the registry record, so the size and precision of any score changes cannot be assessed from that record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a completed single-group pilot study and identifies the MDS-UPDRS total score as its primary outcome. It does not report numerical primary-outcome results. In particular, there are no listed means or standard deviations at the specified assessment times, and no reported estimate of change, confidence interval, or statistical test result. The absence of these results means the magnitude and precision of any measured score changes cannot be evaluated from the registry record.
The record lists 27 outcome measures and no analyses. That entry does not establish that no analyses were conducted; it means analyses are not listed in the registry record. Nor does the completed status imply that results were posted. The record supplies design and timing information, but it does not provide the numerical outcome data needed to describe a trajectory in MDS-UPDRS scores.
As a general statistical point, a mean describes the average score in the group, while a standard deviation describes how dispersed individual scores are around that mean. An estimate of change can be more informative when paired with an uncertainty interval, because the interval communicates how imprecisely the change is estimated. None of these numerical summaries for the primary outcome is reported in the registry record, so no direction or size of change should be asserted.
The single-group design also limits interpretation. Without a comparator, changes observed over time cannot be separated from natural fluctuation, expectations, other care, or measurement effects using a randomized between-group contrast. This does not negate the descriptive purpose of a pilot study, but it means that the registry record cannot support a comparative treatment-effect estimate.
The registry does report safety counts. It lists no participants affected by a serious adverse event among 12 at risk, and lists 11 participants affected by other adverse events among 12 at risk. These counts are descriptive and should not be read as a complete account of event types, timing, severity, or causal attribution. The record lists no serious adverse event terms. It also reports zero deaths.
The listed enrollment is 12, making the study a small pilot in scale. Estimates from a study of this size would generally be uncertain, particularly for outcomes with substantial variation. Here, the numerical outcome summaries and uncertainty estimates are not available, so the actual degree of precision cannot be judged. The key interpretation is therefore about what the record can establish: it documents the study design, scheduled measures, and safety counts, but does not report the primary endpoint results needed to quantify clinical changes.
9. Statistical Methods Explained
The registry identifies the primary outcome as a continuous measure summarized by a mean and standard deviation. The MDS-UPDRS total score is formed by summing ratings across 65 items. On a continuous outcome, the mean gives a measure of the group's average score, while the standard deviation describes the spread of scores around that average. These summaries answer different questions: the mean concerns the group’s central level, and the standard deviation concerns variability among scores.
What would an uncertainty interval add?
In general, a confidence interval expresses the uncertainty around an estimated quantity. A narrow interval indicates greater precision than a wide interval, under the assumptions used to construct it. It is not a guarantee that the true value falls within the interval, and it is not a measure of how important a change is. No confidence interval for the primary outcome is reported in the registry record, so precision cannot be evaluated from the posted numerical results.
What does the assessment schedule mean?
The MDS-UPDRS is scheduled at 7 days after the first drug dose and at 7 and 30 days after the second drug dose. These are repeated observations at distinct times, not separate treatment groups. A statistical analysis of repeated measurements may account for the fact that observations from the same participant are related. The registry record does not report the model, method, or any other analysis details used for these measurements.
The record says the primary endpoint is summarized as a mean with standard deviation, but it does not give numerical summaries at the scheduled times. Without those values, it is not possible to describe the average score at each time or quantify how scores changed. An analysis plan, including whether the endpoint was analyzed as a change from baseline or by another approach, is not reported in the registry record.
Why does the single-group structure matter?
General statistical interpretation depends on the design that generated the data. In a randomized comparison, an estimated difference between groups can provide a basis for assessing relative outcomes under the assumptions of that design. This study is recorded as single-group, with allocation not applicable and no masking. There is no listed concurrent control group. Any within-group change would therefore remain descriptive and would not isolate the effect of psilocybin therapy from other possible influences.
Masking is recorded as none. In general, knowledge of treatment and assessment timing can affect reported experiences, participant expectations, and some assessments. The primary outcome is clinician-administered, but the record does not explain whether outcome assessors were otherwise protected from knowledge of treatment. Such details are not reported in the registry record.
How should planning calculations be read?
The record describes sample-size calculations as planning illustrations based on an observed effect, not as the trial's original design. It specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the planned effect is a stated fraction of the observed effect. These are assumptions for hypothetical future planning, not observed power and not a description of the actual single-group design.
In general, a sample-size calculation asks how many participants per arm might be needed to detect an assumed effect under specified statistical assumptions. Such a calculation is only as relevant as its assumptions. Because this study has a single group, an equal-allocation, two-arm illustration does not describe the study's actual design. The registry record does not report the original sample-size justification, and numerical outcome findings needed to assess the observed effect are not reported in the registry record. Planning illustrations should therefore not be treated as evidence that the study was adequately powered or as a result of the trial.
What can be inferred from the analysis listing?
The registry lists 27 outcome measures and zero analyses. This distinguishes registered outcome measures from posted statistical analyses. It does not establish what analyses were performed outside the registry or whether a separate report exists. The registry record does not report the statistical methods, analysis populations, handling of repeated observations, or adjustment for multiple outcomes. Without these details and numerical estimates, readers cannot reconstruct an inferential analysis or verify how uncertainty was calculated.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 27 outcome measures, while the number of analyses listed is zero. It identifies the MDS-UPDRS total score as the primary outcome, but a complete statistical analysis plan is not reported in the registry record. The record does not report whether secondary outcomes were tested formally, whether multiplicity adjustments were planned, or how outcomes were prioritized beyond the primary designation.
As a general statistical issue, evaluating many outcomes can increase the chance that at least one result appears notable by chance if each is tested separately. Adjusting for multiplicity is one way to address that issue, though the suitable approach depends on the questions and analysis plan. No adjustment method is reported in the registry record. Because numerical analyses are also absent, there are no reported significance tests to interpret in relation to multiplicity.
Missing data are documented for the MDS-UPDRS assessment 7 days after the first drug dose. The registry states that incomplete data for one participant meant a total score was unavailable for the full analysis population, and attributes the missing score to a data-entry error. The accompanying explanation of that error is incomplete in the registry record. The record does not describe the statistical handling of this missing score or identify the analysis population used.
In general, missingness can affect estimates if the participants with observed outcomes differ systematically from those without them. The extent and direction of any such effect cannot be determined from the registry entry. The record does not report whether the missing value was excluded, imputed, or handled through another method. It also does not establish completeness at other time points. Accordingly, interpretation should remain limited to the documented missing assessment and the lack of reported analysis details.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Psilocybin Therapy | 0 | 12 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Psilocybin Therapy | 0 of 12 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Psilocybin Therapy | 11 of 12 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Psilocybin Therapy |
|---|---|---|
| Anxiety | Psychiatric disorders | 11 of 12 |
| Nausea | Gastrointestinal disorders | 11 of 12 |
| Blood pressure increased | Cardiac disorders | 9 of 12 |
| Headache | Musculoskeletal and connective tissue disorders | 8 of 12 |
| Tachycardia | Cardiac disorders | 3 of 12 |
| Tremor | Nervous system disorders | 3 of 12 |
| Sensory disturbance | Psychiatric disorders | 3 of 12 |
| Motor dysfunction | Nervous system disorders | 2 of 12 |
| Insomnia | General disorders | 2 of 12 |
| Feeling jittery | Psychiatric disorders | 1 of 12 |
The registry lists 12 participants at risk for serious adverse events and zero affected by a serious adverse event. It lists 12 participants at risk for other adverse events and 11 affected. Deaths are recorded as zero. These are counts of participants affected, as represented in the registry record; they should not be interpreted as counts of individual event episodes.
The record does not list terms for serious adverse events. It also does not provide event descriptions, timing, severity grading, duration, or an assessment of whether events were considered related to treatment. The “other adverse events” count does not identify which events occurred. Therefore, the counts alone cannot characterize the kinds of events or their clinical context.
In general, safety counts are descriptive. A count of affected participants does not establish causation, and absence of a recorded serious event does not establish that a treatment is free of risk. The study is a single-group pilot with a listed enrollment of 12, so these figures should be read as observations recorded for this study, not as a comparative estimate of risk. More detailed event-level safety reporting is not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a Phase 2 pilot study of psilocybin therapy for depression and anxiety in people with Parkinson's disease was registered as completed. It describes a single-group design, a dosing and support schedule, a primary clinician-administered Parkinson's disease symptom measure, and safety counts. It does not report numerical results for the primary endpoint. As a result, the record does not show the size, direction, or precision of any change in MDS-UPDRS total score.
The study's stated purpose includes safety, tolerability, and feasibility. Those aims are distinct from proving comparative efficacy. A pilot study can describe the conduct of an intervention and inform further research, but this registry record does not provide numerical findings sufficient to judge the primary outcome or to quantify a treatment effect. The single-group design also lacks a concurrent control comparison, so any within-group change would not by itself demonstrate that the intervention caused that change.
The safety entries report zero participants affected by a serious adverse event, 11 affected by other adverse events, and zero deaths. Those entries are not a complete event narrative. Serious event terms are not listed, and descriptions of other events and causal attribution are not reported in the registry record. The counts should not be generalized beyond the study participants and record.
These limitations do not mean that the study produced no information. The registry records the planned outcome schedule and an instance of missing MDS-UPDRS data, and it documents the study's design and safety summaries. But conclusions about symptom-score outcomes, uncertainty, statistical significance, or comparative benefit require results and analysis details that are not reported in the registry record. The meaning is therefore chiefly about the scope of evidence available: this record describes a completed pilot and selected safety counts, not a quantified estimate of treatment effect.
13. Why This Trial Matters Statistically
This study raises statistical issues that are important when interpreting early clinical research. Its single-group structure is central: without a control group, the design cannot estimate a randomized contrast between psilocybin therapy and an alternative condition. This distinction matters even when a study measures participants repeatedly, because repeated scores do not substitute for a concurrent comparator.
The primary endpoint is a clinician-administered total score built from several symptom domains. That structure makes clear outcome definition and transparent reporting important. The registry specifies item scoring, the direction of interpretation, and assessment timing, which helps explain what the measure represents. At the same time, numerical results and analysis methods are not reported, so readers cannot evaluate the observed average scores or their precision.
The record also illustrates the difference between outcome registration and analysis reporting. It lists 27 outcome measures but no analyses. A registered measure indicates that an outcome was identified for the study record; it does not supply an estimate, uncertainty interval, or inferential result. With multiple outcomes, reporting how analyses were selected and whether multiplicity was addressed is particularly relevant, yet those details are not reported in the registry record.
Finally, the documented missing score and brief safety counts show why transparent reporting includes more than a headline result. Readers need to know which observations were unavailable, how analyses handled them, and what event categories include. This record gives some of that context but not the full analysis or event detail. Statistically, the trial matters as a reminder that design, measurement, missingness, and reporting completeness jointly determine what can be concluded from a pilot study.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The principal limitation for interpreting outcomes is that numerical primary-endpoint results are not reported in the registry record. Means, standard deviations, estimates of change, confidence intervals, and statistical tests are not available. Although the study is marked completed, completion status does not supply these results.
The single-group design has no listed comparator, and masking is recorded as none. Thus, the record does not support a randomized between-group estimate. The study's stated enrollment is 12, which limits the scale of the evidence, although precision cannot be assessed without numerical outcome summaries. The registry does not report the original sample-size rationale or a statistical analysis plan.
The primary measure has a specified assessment schedule, but a total score is missing for one participant at 7 days after the first drug dose. The record attributes this to a data-entry error but does not report how the missing value was handled. It does not identify the analysis population or describe methods for repeated measurements. Therefore, the impact of the missing score on any estimate cannot be assessed.
Safety reporting is also limited. The registry lists affected-participant counts but no serious adverse event terms, and it does not describe the other adverse events or their timing, severity, or attribution. Further population details, including eligibility criteria, are not reported in the registry record. These gaps restrict interpretation to the design features and counts that are documented and prevent a fuller assessment of outcomes or safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Psilocybin Therapy for Depression and Anxiety in Parkinson's Disease — NCT04932434.
- Registry record last updated 2026-09-03; status last verified 2026-08.
- Results first posted 2026-09-03.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT04932434 is a completed Phase 2 pilot study of psilocybin therapy for depression and anxiety in people with Parkinson's disease. The registry lists a single-group design, no masking, and an enrollment of 12. The intervention description includes one or two doses in a monitored setting, with preparation and integration sessions.
The primary outcome is the MDS-UPDRS total score, assessed at 7 days after the first dose and at 7 and 30 days after the second dose. One total score was unavailable at the first post-dose assessment because of a documented data-entry error. The registry lists 27 outcome measures and no analyses.
Safety entries list zero participants affected by a serious adverse event, 11 affected by other adverse events, and zero deaths. Numerical primary-outcome results, detailed event descriptions, analysis methods, and the analysis population are not reported in the registry record. The design and posted safety counts can therefore be described, but the magnitude and precision of primary-outcome changes cannot be assessed.