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StutteringPhase 2NCT07296328

Effects of Psilocybin on Speech Fluency, Struggle, and Brain Activity in People Who Stutter

A Phase 2 study testing Psilocybin and Speech therapy in people with Stuttering, run by NYU Langone Health at 1 site in United States.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts
Official record
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Trial summary

This Phase 2a clinical trial is an open-label, single-group, within-subjects pilot study designed to evaluate the safety, feasibility, and preliminary efficacy of psilocybin as a therapeutic intervention for adults with developmental stuttering. Read more about this study

Who is it for?
Ages 18 to 50 years
Conditions the study is for
Stuttering
What is being tested?
Psilocybin and Speech therapy
Could I receive a placebo?
No, everyone receives an active treatment
How many people
25 participants
Where
1 siteUnited States
Study dates
15 Jan 2026to 1 Apr 2027
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 50 years
  • All sexes
  • No healthy volunteers
  • Adult

Who may be able to join

  • Are able to provide voluntary informed consent
  • Are able to read, speak, and understand English, as documented during the informed consent process.
  • o Non-English-speaking subjects will be excluded because the study is using only validated English-language versions of assessment instruments.
  • Are 18 to 50 years old, inclusive, at Screening visit.
  • Have diagnosis of mild-moderate to severe stuttering based on either the SSI-4 or OASES; also confirmed stuttering by stuttering specialist.
  • Are able and willing to adhere to all study requirements, including attending all study visits and therapy sessions, and completing all assessments.
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  • Agree to refrain from any non-prescribed psychotropic substance or illicit drug use for at least 72 hours prior to investigational product (IP) administration, and for at least 24 hours before each fMRI assessment visit, with the exceptions of nicotine and caffeine. Regarding nicotine, they must agree not to use nicotine for at least 1 hour before and 6 hours following IP administration, and for at least 1 hour before fMRI scans. Regarding caffeine, they must agree to consume approximately their usual amount of caffeine on the morning of Day 0 (prior to IP administration).
  • Agree to refrain from taking all non-prescription medications and supplements (nutritional and herbal) for at least 1 week prior to the IP administration session unless approved by the Investigator.
  • Can swallow capsules.
  • Subjects who are able to become pregnant must comply with the following conditions:
  • Subjects are considered able to become pregnant unless they
  • Do not have a uterus;
  • Are postmenopausal (has had 12 months of natural amenorrhea with a matching clinical profile [age, history of vasomotor symptoms]) prior to Screening Part 2; or
  • Are surgically sterile (documented hysterectomy, bilateral salpingectomy, or bilateral oophorectomy).
  • Subjects who are able to become pregnant must
  • Have a negative pregnancy test at Screening (Reassessed at Day 0 (pre-IP administration);
  • Not be currently breastfeeding;
  • Not intend to become pregnant during participation in this study;
  • Agree to use a highly effective form of contraception from the time of Screening until 7 days after the IP Administration Session. Highly effective forms of contraception include:
  • Consistent and correct usage of established oral contraception;
  • Injected or implanted hormonal methods of contraception;
  • Established intrauterine device or intrauterine system;
  • Bilateral tubal ligation;
  • Intercourse with a partner who has undergone effective surgical sterilization, provided that partner is the sole sexual partner of the study subject;
  • Abstinence from penile/vaginal intercourse, if the Investigator determines that the subject can reliably adhere to the plan, based on evaluation of the participant's preferred and usual lifestyle and social circumstances.
  • Agree not to donate or bank eggs from the time of Screening Part 2 until 7 days after the IP Administration Session.
  • If able to become pregnant or produce viable sperm (male or female), are willing to use approved contraception for duration of the trial.

Who cannot join

  • Pregnancy or lactation.
  • Any medical condition that would preclude safe participation in the study, including the following, as determined by medical history review, physical examination, electrocardiogram (ECG), and clinical laboratory tests:
  • Seizure disorder
  • Significantly impaired liver function, defined as 1) alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) > 5 × upper limit of normal (ULN); 2) ALT or AST > 3 × ULN with concomitant total bilirubin > 2.0 × ULN; or 3) ALT or AST ≥ 3 × ULN with the appearance of fatigue, nausea, vomiting, right upper quadrant pain or tenderness, fever, rash, and/or eosinophilia.
  • Cardiovascular disease including coronary artery disease, angina, history of arrhythmia (unless a successful ablation has been performed), heart failure, history of heart valve replacement, and history of cerebrovascular accident or transient ischemic attack.
  • Uncontrolled hypertension with systolic blood pressure > 140 mmHg or diastolic blood pressure > 90 mmHg. (Note: participants who otherwise meet all eligibility criteria during the screening visit will have 3 opportunities to produce 1 blood pressure reading ≤ 140/90 mmHg (each reading will be collected at least 15 minutes apart). If blood pressure at Screening is consistently elevated (> 140/90 mmHg across all 3 attempts), participants may be referred to their primary care provider (PCP) for management of hypertension. Participants may continue study participation if the Investigator believes that it is likely that hypertension can be controlled prior to the IP administration session, and the patient is able to provide documentation of adequate control (BP < 140/90 mmHg) prior to the PI administration session.)
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  • Resting heart rate > 100 bpm (Note: participants will have an opportunity to return once within the 30-day screening window to make 3 additional attempts at a resting heart rate ≤ 100 bpm.).
  • Serious ECG abnormalities (e.g., evidence of ischemia, myocardial infarction, QT interval corrected for heart rate [QTc] prolongation (QTc > 0.450 seconds), arrhythmia, or conduction abnormalities that increase the risk of arrhythmia.
  • Hyperthyroidism
  • Insulin-dependent diabetes
  • Bradycardia (e.g., heart rate <50 bpm)
  • Orthostatic hypotension
  • Schizotypal and paranoid personality disorders
  • Given potential use of diazepam as an ancillary medication, moderate or greater hepatic impairment (Child-Pugh score ≥ 7) is exclusionary.
  • Any other medical condition which precludes safe participation in the study in the medical opinion of the Investigator. (Note: medical history will be updated on Day 0. Those not meeting the criterion may be rescheduled once within 14 days if the criterion is likely to resolve within 14 days in the judgement of the Investigator.)
  • Have any of the following Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) psychiatric disorders, as determined by the Mini International Neuropsychiatric Interview (MINI) and Psychiatric History at the Screening Visit: (Note: psychiatric history will be re-evaluated on Day 0, but the MINI will not be re-administered on Day 0)
  • Lifetime history of schizophrenia spectrum or other psychotic disorder (including substance or medication-induced psychosis or psychosis due to a co-occurring medical condition).
  • Major depressive disorder (MDD)Post traumatic stress disorder (PTSD)
  • Cluster B personality disorders (antisocial personality disorder, borderline personality disorder, histrionic personality disorder, and narcissistic personality disorder)
  • Bipolar I disorder, Bipolar II disorder, and Cyclothymic disorder
  • Have active suicidal ideation with intent, based on Columbia-Suicide Severity Rating Scale (C-SSRS) assessment (severity score > 3) at the Screening visit, confirmed by the Investigator. (Note: this criterion will be reassessed at each visit that occurs prior to Day 0, and on Day 0. Participants will be discharged if actively suicidal, and appropriate follow-up will be arranged.
  • Have made a medically significant suicide attempt (i.e., one that had a significant possibility of causing death or permanent harm in the absence of intervention) within the past 12 months, based on Screening C-SSRS assessment and confirmation by the Investigator. (Note: this criterion will be reassessed at each visit that occurs prior to Day 0, and on Day 0. Participants will be discharged if actively suicidal, and appropriate follow-up will be arranged.)
  • Have a family history (first degree relatives) of schizophrenia, schizoaffective disorder, or bipolar disorder type 1.
  • Have a history of hallucinogen use disorder.
  • Have a history of hallucinogen persisting perceptual disorder (HPPD).
  • Have any use of classic psychedelics in the past 1 year.
  • Have > 25 lifetime uses of classic psychedelics.
  • Incarcerated or have pending legal action that could prevent participation in study activities.
  • Are unable or unwilling to discontinue taking any protocol-prohibited medications and supplements. (A detailed list of exclusionary medications is found in Section 6.5 of the protocol.) Prohibited medications and supplements must have been stopped for at least 5 elimination half-lives or 14 days, whichever is longer, prior to Day 0 (Note: Psychiatric medications will not be discontinued or changed in order to allow study participation. Concomitant medications will be reassessed on Day 0. Any patient who has started prohibited medications will be discharged from the study.)
  • Have a known allergy or hypersensitivity to psilocybin or any of the materials contained in the IP used in the study.
  • Have an allergy, hypersensitivity, or other contraindication that would preclude safe treatment of acute hypertension, anxiety, or psychotic symptoms if necessary, during or immediately after the IP Administration Session, using the adjunctive medications used in this pilot study to treat these symptoms (i.e., unable to take captopril and unable to take clonidine; unable to take diazepam; or unable to take olanzapine).
  • Have any other medical, psychiatric, or psychosocial disorder, symptom, condition, or situation that is likely to interfere with the establishment of rapport, adherence to study requirements, or safe administration of psilocybin or functional magnetic resonance imaging (fMRI) scanning, based on the judgement of the Investigator. (Note: This criterion will be reassessed on Day 0. Those not meeting the criterion will not be randomized but may be rescheduled once within 14 days if the criterion is likely to resolve within 14 days in the judgement of the Investigator.)
  • Inability to safely complete fMRI sessions (MRI screening form)
  • Any history of severe traumatic brain injury (assessed using the Ohio State University Traumatic Brain Injury Identification Method (OSU TBI-ID) modified). (Note: If current (past 12 months) mild/moderate Traumatic Brain Injury (TBI) and Central Sensitization Inventory (CSI) score >/= 12 (for either lifetime month or current month), the PI will determine eligibility.)

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Eric Jackson, PhD contact

212-992-9470

Ej34@nyu.edu

United States1 site

  • NYU Langone Health

    New York, New York, 10016

Other trials in United States

About this study

This Phase 2a clinical trial is an open-label, single-group, within-subjects pilot study designed to evaluate the safety, feasibility, and preliminary efficacy of psilocybin as a therapeutic intervention for adults with developmental stuttering. This pilot study will assess whether further research to explore the potential benefits of psilocybin-assisted therapy for improving clinical outcomes in individuals who stutter, is warranted. The aims of this study include:

  • Aim 1: Assess the safety and feasibility of psilocybin as a therapeutic agent for stuttering.
  • Aim 2: Evaluate the effects of psilocybin on objective and subjective measures of stuttering severity, struggle, and well-being.
  • Aim 3: Explore the therapeutic neural mechanisms of psilocybin in stuttering.
Conditions
Stuttering
Being tested
Psilocybin, Speech therapy
Keywords
Stuttering, Psilocybin, Stutter
Medical subject headings
Stuttering

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • PsilocybinDrug

    Participants will receive a single oral high-dose of psilocybin, 25 mg.

  • Speech therapyBehavioural

    Speech therapy will consist of standard stuttering modification therapy, which includes four phases: Identification, Desensitization, Modification, Stabilization.

Study groups in NCT07296328
Study groupRoleWhat they receive
Adult stutterersExperimentalParticipation will occur over an 8-week, 10-session period. Six sessions speech therapy; one preparatory therapy session prior to the drug administration session; one 8-hour drug administration session (25 mg of psilocybin); two follow-up therapy sessions following the drug administration session.
Receives: Drug: Psilocybin; Behavioral: Speech therapy

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change in Stuttering Severity Instrument - 4th Edition (SSI-4) total score

    The Stuttering Severity Instrument-4th Edition (SSI-4) provides a total score that is compared to age-specific norms to determine severity, with ranges for "Very Mild" to "Very Severe". The SSI-4 calculates individual scores for frequency (2-18), duration (2-18), and physical concomitants (0-20). These individual scores are combined to create a total score, which is then ranked against norms to provide a verbal severity descriptor, such as mild, moderate, severe, or very severe.

    Measured: Week 4, Week 12

  2. Change in frequency subcomponent score of the SSI-4

    The Stuttering Severity Instrument-4th Edition (SSI-4) provides a total score that is compared to age-specific norms to determine severity, with ranges for "Very Mild" to "Very Severe". The SSI-4 calculates individual scores for frequency (2-18), duration (2-18), and physical concomitants (0-20). These individual scores are combined to create a total score, which is then ranked against norms to provide a verbal severity descriptor, such as mild, moderate, severe, or very severe.

    Measured: Week 4, Week 12

  3. Change in duration subcomponent score of the SSI-4

    The Stuttering Severity Instrument-4th Edition (SSI-4) provides a total score that is compared to age-specific norms to determine severity, with ranges for "Very Mild" to "Very Severe". The SSI-4 calculates individual scores for frequency (2-18), duration (2-18), and physical concomitants (0-20). These individual scores are combined to create a total score, which is then ranked against norms to provide a verbal severity descriptor, such as mild, moderate, severe, or very severe.

    Measured: Week 4, Week 12

  4. Change in physical concomitants subcomponent score of the SSI-4

    The Stuttering Severity Instrument-4th Edition (SSI-4) provides a total score that is compared to age-specific norms to determine severity, with ranges for "Very Mild" to "Very Severe". The SSI-4 calculates individual scores for frequency (2-18), duration (2-18), and physical concomitants (0-20). These individual scores are combined to create a total score, which is then ranked against norms to provide a verbal severity descriptor, such as mild, moderate, severe, or very severe.

    Measured: Week 4, Week 12

  5. Change in Overall Assessment of the Speaker's Experience of Stuttering - Adults (OASES-A) score

    The OASES-A is a tool used by speech-language pathologists to measure the adverse impact of stuttering on an adult's life. It consists of 100 questions rated on a 5-point scale (1-5). The scores from individual questions are added together to create an overall score. The total score is then used to determine the "Impact Rating" on a scale from mild to severe. Higher scores indicate higher levels of negative impact.

    Measured: Week 4, Week 12

Secondary outcomes (5)

  1. Change in self-reported stuttering severity Wright and Ayre Stuttering Self-Rating Profile (WASSP) score

    The WASSP produces a profile of scores across five subscales. There is a total of 26 items each scored on a seven-point Likert-type scale. A score of '1' represents the least severe/negative perception, while a '7' represents the most severe/negative perception on each scale. Total scores range from 26-182, with higher scores indicating a greater negative impact of stuttering on their life.

    Measured: Week 4, Week 12

  2. Change in the Brief Version of the Unhelpful Thoughts and Beliefs About Stuttering Scales (UTBAS-6) total score

    The UTBAS-6 is a six-item screening questionnaire for adults who stutter to measure unhelpful thoughts and beliefs associated with speech anxiety. The UTBAS-6 has a subscale score range of 6 to 30 and a total score range of 18 to 90. A higher score indicates more frequent unhelpful thoughts and greater anxiety related to stuttering.

    Measured: Week 4, Week 12

  3. Change in Brief Fear of Negative Evaluation Scale (BFNE-S) total score

    The BFNE-S consists of 8 items that are rated on a five-point likert scale from 1 (not at all characteristic) to 4 (extremely characteristic). Scores range from 0 to 32. A score of 25 or higher may indicate clinically significant social anxiety.

    Measured: Week 4, Week 12

  4. Change in the Social Interaction Anxiety Scale (SIAS) score

    The SIAS is a 20-item self-report questionnaire that measures the severity of social anxiety. Each item is rated from 0 (not at all characteristic or true of me) to 4 (extremely characteristic or ture of me). Scores can range from 0 (no social anxiety) to 80 (maximum social anxiety). A score of 36 or higher is often considered clinically significant, suggesting the presence of social anxiety.

    Measured: Week 4, Week 12

  5. Change in Stuttering Anticipation Scale (SAS) score

    The SAS is a 25-item self-report tool measuring specific action responses (avoidance, physical changes, approach) on a 7-point scale from 1 (Never) to 7 (always). Scores range from 25-175, with higher scores indicating more frequent anticipatory behaviors.

    Measured: Week 4, Week 12

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted22 Dec 2025
  2. Study start15 Jan 2026 (estimated)
  3. Primary completion1 Apr 2027 (estimated)
  4. Study completion1 Apr 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
25 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07296328
Sponsor's protocol ID
25-00244
Status last verified
Dec 2025
First submitted
18 Dec 2025
Last updated
22 Dec 2025
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: The de-identified participant data from the final research dataset will be shared upon reasonable request beginning 9 to 36 months after publication or as required by a condition of awards or supporting agreements, provided the requesting investigator executes a data use agreement with NYU Langone Health. This instance of data sharing will also require separate IRB review as well as review from NYU Langone's Data Sharing Strategy Board (DSSB). Requests should be directed to: Michael.bogenschutz@nyulangone.org. The protocol and statistical analysis plan will be posted on Clinicaltrials.gov only as required by federal regulation or supporting awards and agreements.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing Psilocybin and Speech therapy in people with Stuttering, run by NYU Langone Health at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 27 inclusion and 34 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: opening soon, as of the sponsor's last update on 22 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Eric Jackson, PhD (212-992-9470, Ej34@nyu.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change in Stuttering Severity Instrument - 4th Edition (SSI-4) total score (time frame: Week 4, Week 12). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07296328.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Dec 2025.

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