StutteringNCT07354139
Using Non-invasive Brain Stimulation to Explore Potential Treatments to Reduce Speech Errors in Adults Who Stutter
A study testing High - Definition Transcranial Direct Current Stimulation in people with Stuttering and Fluency Disorder, run by The University of Texas at Dallas at 1 site in United States.
Trial summary
The goal of this study is to find out whether a type of noninvasive brain stimulation can help reduce speech errors, such as repetitions, blocks, and prolongations, in people who stutter. This pilot study will help researchers design future treatments to see if targeting certain brain areas can improve speech fluency. Read more about this study
- Who is it for?
- Ages 22 years and older
- Conditions the study is for
- Stuttering, Fluency Disorder
- What is being tested?
- High - Definition Transcranial Direct Current Stimulation
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 50 participants
- Where
- 1 siteUnited States
- Study dates
- 17 Mar 2026to 28 Feb 2027
- Phase
- Interventional
- 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 22 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Must be 22 years old or older
- May be bi/multilingual but must speak English as dominant language.
- Must be diagnosed or suspected of developmental stuttering disorder. Participants will be administered the Stuttering Severity Instrument 4 and categorized as typical speakers or mild, moderate, or severe stutterers.
- Must be able to attend the session at the physical location within the clinic
Who cannot join
- Patients with preexisting speech/language disorders or previously diagnosed neurological disorders (including but not limited to apraxia of speech, cerebral palsy, dysarthria, tourettes, or any other neurological/motor condition) that affect speech/language (except stuttering) are excluded to minimize the interference of atypical brain activity.
- Participants who have acquired or neurogenic stuttering (stuttering resulting from a brain injury) are excluded, as this study focuses exclusively on the effects of developmental stuttering.
- Participants with a history of seizures
- Participants with unexplained episodes of loss of consciousness, since such condition could be related with brain alterations or epilepsy
- Participants with unstable or non controlled neuropsychiatric illness
- Participants having implanted brain medical devices
Show all 18Show fewer
- Participants with implanted pacemakers
- Participants having any electrically,magnetically or mechanically activated implant
- Participants having cardiac, neural or medication implants
- Participants having vascular clips or any other electrically sensitive support system in the brain
- Participants with serious brain injury
- Participants showing damage of skin at sites of stimulation (the device can only be used in healthy skin without wounds, otherwise the resistance to current can be altered)
- Participants suffering from skin problems, such as dermatitis, psoriasis or eczema
- Participants suffering from severe or frequent headaches
- Participants with any serious life-threatening disease such as congestive heart failure, pulmonary obstructive chronic disease, or active neoplasia
- Pregnant women
- Participants may not consume alcohol or controlled substances within 24 hours of the scheduled appointment
- Participants will complete an additional screener upon enrollment to assess medical history and current drug/medication use that may conflict with the study.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Callier Clinical Research Center
Richardson, Texas, 75080
Christine H Abasi, MS-SLP, 817-718-7301, christine.abasi@utdallas.edu
About this study
Official title: Examining Speech Production Errors in Stuttering Through High Definition - Transcranial Direct Current Stimulation
The goal of this study is to find out whether a type of noninvasive brain stimulation can help reduce speech errors, such as repetitions, blocks, and prolongations, in people who stutter. This pilot study will help researchers design future treatments to see if targeting certain brain areas can improve speech fluency. The study will look at how people speak and behave during both speaking and non-speaking tasks before and after the brain stimulation.
Participants will complete an online survey about 24 hours before coming to the clinic. The clinic visit will last about 3 hours and will include three phases. All parts of the study will be audio-recorded.
Read more
- Pre-Testing: Participants will first complete a stuttering evaluation to determine whether they are typical speakers or have a mild, moderate, or severe stutter. Then, they will do several speaking and non-speaking tasks.
- Brain Stimulation: Participants will receive a session of targeted noninvasive brain stimulation (HD-tDCS).
- Post-Testing: After the brain stimulation, participants will repeat the same evaluation and tasks they completed during pre-testing.
Brain stimulation description:
HD-tDCS is a non-invasive technique that requires the placement of several sensors (metal electrodes) on a special cap and saline gel on your head. Very low levels of constant electrical current are delivered to specifically targeted areas of the brain via these electrodes. You may experience a slight feeling of dizziness when starting the stimulation. This occurs in a small number of subjects. This takes only a few seconds and does not affect balance after the stimulation has been completed. Several research centers have previously investigated the use of this device on healthy subjects and have found the device to be safe with no direct effect on the person's well-being. Following stimulation, participants will have the opportunity to rinse out residual gel from hair and scalp.
- Conditions
- Stuttering, Fluency Disorder
- Being tested
- High - Definition Transcranial Direct Current Stimulation
- Keywords
- Stuttering, HD-tDCS, neuromodulation, speech, fluency
- Medical subject headings
- Stuttering, Speech
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
High - Definition Transcranial Direct Current StimulationDevice
Also called Neuroelectrics, Starstim, HD-tDCS, Non-invasive brain stimulation
HD-tDCS protocol for LIFG group is as follows: A single 20-minute session with one anode at F7 at 1 mA and four 0.25 mA cathodes at T7, FP1, AF3, FC5 at 0.25 mA
HD-tDCS protocol for the Pre-SMA group is as follows: A single 20-minute session with one anode 1mA at Fz 1 mA and four 0.25 mA cathodes at FP1, FP2, F7, F8
| Study group | Role | What they receive |
|---|---|---|
| Left Inferior Frontal Gyrus | Experimental | This arm is designed to analyze if treatment on the speech production area of the brain (also known as Broca's area) will decrease speech errors and increase ease of production in people who stutter Receives: Device: High - Definition Transcranial Direct Current Stimulation |
| Presupplementary motor area | Experimental | This arm is designed to investigate whether treatment targeting the motor planning region of the brain can reduce speech errors and increase ease of production in individuals who stutter. Receives: Device: High - Definition Transcranial Direct Current Stimulation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Stuttering Severity Instrument - 4
Stuttering Severity Instrument-Fourth Edition (SSI-4) is a reliable and valid norm-referenced stuttering assessment that can be used for both clinical and research purposes. It measures stuttering severity in both children and adults in the four areas of speech behavior:
frequency duration physical concomitants naturalness of the individual's speech.
The SSI-4 scores stuttering severity by combining measures of frequency (% syllables stuttered), duration (length of longest stutters), and physical concomitants (secondary behaviors) into a total score, which is then converted to a percentile rank and severity level (very mild to very severe) using age-specific standards. Higher percentile scores indicate more severe stuttering, with ranges like 1-4% being very mild and 96-99% very severe.
Measured: Measured at singular clinical visit (baseline)
Predictive Naming Task
Participants are instructed to name images on a screen, given phrases that indicate high or low predictability for the target word.
Task is measured by accuracy (number of correct answers) and participant response time.
Measured: Measured at singular clinical visit (baseline)
Secondary outcomes (2)
Overall Assessment of the Speaker's Experience of Stuttering
The Overall Assessment of the Speaker's Experience of Stuttering (OASES) gives clinicians and researchers an impact rating and impact score, which reflect the degree of adverse impact a speaker experiences due to stuttering. The impact score combines information about (a) the speaker's perceptions about stuttering; (b) the negative affective (feelings), behavioral (actions), and cognitive (thoughts) reactions that the speaker has to stuttering; (c) the functional communication difficulties a speaker may have in different speaking environments; and (d) the impact of stuttering on the speaker's overall quality of life. The OASES is the only published tool that specifically examines Quality of Life in people who stutter.
The OASES score reflects the impact of stuttering on a person's life, using a 1-5 rating scale where higher scores indicate a more severe impact, categorized into mild, mild-to-moderate, moderate, moderate-to-severe, and severe levels.
Measured: Completed during enrollment process (24 hours pre-visit during consent)
Button push Go/NoGo task
Participants are instructed to press a button when category A (objects) is presented on the screen, but not to push when category B (animals) is shown.
Task is measured by accuracy (number of correct answers) and participant response time.
Measured: Measured at singular clinical visit (baseline)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Jan 2026
- Study start17 Mar 2026
- Primary completion28 Feb 2027 (estimated)
- Study completion28 Feb 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for StutteringStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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 N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- The University of Texas at Dallas
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, John Hart, Jr., The University of Texas at Dallas
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07354139
- Sponsor's protocol ID
- IRB-25-184
- Status last verified
- Oct 2026
- First submitted
- 15 Jan 2026
- Last updated
- 26 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- Yes: De-identified data and clinical study report will be available for the public
Study at a glance
From the registry record, last updated by the sponsor on 26 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Examining Speech Production Errors in Stuttering Through High Definition - Transcranial Direct Current Stimulation
- ClinicalTrials.gov ID
- NCT07354139
- Acronym / sponsor ID
- IRB-25-184
- Conditions
- Stuttering, Fluency Disorder
- Keywords
- Stuttering, HD-tDCS, neuromodulation, speech, fluency
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 50 participants (estimated)
- Lead sponsor
- The University of Texas at DallasUniversity, hospital or other
- Study start
- 17 Mar 2026 (actual)
- Primary completion
- 28 Feb 2027 (estimated)
- Study completion
- 28 Feb 2027 (estimated)
- First posted
- 21 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this study is to find out whether a type of noninvasive brain stimulation can help reduce speech errors, such as repetitions, blocks, and prolongations, in people who stutter. This pilot study will help researchers design future treatments to see if targeting certain brain areas can improve speech fluency. The study will look at how people speak and behave during both speaking and non-speaking tasks before and after the brain stimulation.
Participants will complete an online survey about 24 hours before coming to the clinic. The clinic visit will last about 3 hours and will include three phases. All parts of the study will be audio-recorded.
- Pre-Testing: Participants will first complete a stuttering evaluation to determine whether they are typical speakers or have a mild, moderate, or severe stutter. Then, they will do several speaking and non-speaking tasks.
- Brain Stimulation: Participants will receive a session of targeted noninvasive brain stimulation (HD-tDCS).
- Post-Testing: After the brain stimulation, participants will repeat the same evaluation and tasks they completed during pre-testing.
Brain stimulation description:
HD-tDCS is a non-invasive technique that requires the placement of several sensors (metal electrodes) on a special cap and saline gel on your head. Very low levels of constant electrical current are delivered to specifically targeted areas of the brain via these electrodes. You may experience a slight feeling of dizziness when starting the stimulation. This occurs in a small number of subjects. This takes only a few seconds and does not affect balance after the stimulation has been completed. Several research centers have previously investigated the use of this device on healthy subjects and have found the device to be safe with no direct effect on the person's well-being. Following stimulation, participants will have the opportunity to rinse out residual gel from hair and scalp.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Left Inferior Frontal Gyrus | Experimental | Device: High - Definition Transcranial Direct Current StimulationThis arm is designed to analyze if treatment on the speech production area of the brain (also known as Broca's area) will decrease speech errors and increase ease of production in people who stutter |
| Presupplementary motor area | Experimental | Device: High - Definition Transcranial Direct Current StimulationThis arm is designed to investigate whether treatment targeting the motor planning region of the brain can reduce speech errors and increase ease of production in individuals who stutter. |
Who may qualify
- Ages
- 22 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Must be 22 years old or older
- May be bi/multilingual but must speak English as dominant language.
- Must be diagnosed or suspected of developmental stuttering disorder. Participants will be administered the Stuttering Severity Instrument 4 and categorized as typical speakers or mild, moderate, or severe stutterers.
- Must be able to attend the session at the physical location within the clinic
Key exclusion criteria (18 listed)
- Patients with preexisting speech/language disorders or previously diagnosed neurological disorders (including but not limited to apraxia of speech, cerebral palsy, dysarthria, tourettes, or any other neurological/motor condition) that affect speech/language (except stuttering) are excluded to minimize the interference of atypical brain activity.
- Participants who have acquired or neurogenic stuttering (stuttering resulting from a brain injury) are excluded, as this study focuses exclusively on the effects of developmental stuttering.
- Participants with a history of seizures
- Participants with unexplained episodes of loss of consciousness, since such condition could be related with brain alterations or epilepsy
- Participants with unstable or non controlled neuropsychiatric illness
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| High - Definition Transcranial Direct Current StimulationAlso: Neuroelectrics, Starstim, HD-tDCS, Non-invasive brain stimulationHD-tDCS protocol for LIFG group is as follows: A single 20-minute session with one anode at F7 at 1 mA and four 0.25 mA cathodes at T7, FP1, AF3, FC5 at 0.25 mA HD-tDCS protocol for the Pre-SMA group is as follows: A single 20-minute session with one anode 1mA at Fz 1 mA and four 0.25 mA cathodes at FP1, FP2, F7, F8 | Device | Left Inferior Frontal Gyrus, Presupplementary motor area |
Primary outcome
Stuttering Severity Instrument - 4
Time frame: Measured at singular clinical visit (baseline)
Stuttering Severity Instrument-Fourth Edition (SSI-4) is a reliable and valid norm-referenced stuttering assessment that can be used for both clinical and research purposes. It measures stuttering severity in both children and adults in the four areas of speech behavior: frequency duration physical concomitants naturalness of the individual's speech. The SSI-4 scores stuttering severity by combining measures of frequency (% syllables stuttered), duration (length of longest stutters), and physical concomitants (secondary behaviors) into a total score, which is then converted to a percentile rank and severity level (very mild to very severe) using age-specific standards. Higher percentile scores indicate more severe stuttering, with ranges like 1-4% being very mild and 96-99% very severe.
Predictive Naming Task
Time frame: Measured at singular clinical visit (baseline)
Participants are instructed to name images on a screen, given phrases that indicate high or low predictability for the target word. Task is measured by accuracy (number of correct answers) and participant response time.
2 secondary outcomes
Overall Assessment of the Speaker's Experience of Stuttering
Time frame: Completed during enrollment process (24 hours pre-visit during consent)
Button push Go/NoGo task
Time frame: Measured at singular clinical visit (baseline)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Oct 2026.
- Individual participant dataSharing planned: Yes. De-identified data and clinical study report will be available for the public
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing High - Definition Transcranial Direct Current Stimulation in people with Stuttering and Fluency Disorder, run by The University of Texas at Dallas 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 4 inclusion and 18 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: looking for participants now, as of the sponsor's last update on 26 Oct 2026. 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.
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 Christine H Abasi, MS-SLP (8177187301, Christine.abasi@utdallas.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Stuttering Severity Instrument - 4 (time frame: Measured at singular clinical visit (baseline)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 26 Oct 2026.