Using Non-invasive Brain Stimulation to Explore Potential Treatments to Reduce Speech Errors in Adults Who Stutter

NCT07354139 | Recruiting FDA Device

• 1 other identifier: IRB-25-184
• Study Type: interventional
• Target: 50
• Locations: 1 country
• Sites: 1

Brief 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. 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.

1. 1.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.
2. 2.Brain Stimulation: Participants will receive a session of targeted noninvasive brain stimulation (HD-tDCS).
3. 3.Post-Testing: After the brain stimulation, participants will repeat the same evaluation and tasks they completed during pre-testing.

Conditions

Stuttering; Fluency Disorder

Keywords

Stuttering; HD-tDCS; neuromodulation; speech; fluency

Outcome Measures

Primary Outcomes (2)

• 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 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 at singular clinical visit (baseline)

Secondary Outcomes (2)

• Overall Assessment of the Speaker's Experience of Stuttering

  Completed during enrollment process (24 hours pre-visit during consent)

• Button push Go/NoGo task

  Measured at singular clinical visit (baseline)

Study Arms (2)

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

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.

Device: High - Definition Transcranial Direct Current Stimulation

Interventions

High - Definition Transcranial Direct Current Stimulation DEVICE

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

Also known as: Neuroelectrics, Starstim, HD-tDCS, Non-invasive brain stimulation, neuromodulation

Left Inferior Frontal Gyrus; Presupplementary motor area

Eligibility Criteria

• Age: 22 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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
• 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

Sponsors & Collaborators

• The University of Texas at Dallas: lead

Study Sites (1)

Callier Clinical Research Center

Richardson, Texas, 75080, United States

RECRUITING

MeSH Terms

Conditions

Stuttering; Speech

Interventions

Transcutaneous Electric Nerve Stimulation

Condition Hierarchy (Ancestors)

Speech Disorders; Language Disorders; Communication Disorders; Neurobehavioral Manifestations; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Verbal Behavior; Communication; Behavior

Intervention Hierarchy (Ancestors)

Electric Stimulation Therapy; Therapeutics; Physical Therapy Modalities; Rehabilitation; Analgesia; Anesthesia and Analgesia

Central Study Contacts

Christine H Abasi, MS-SLP

CONTACT

8177187301; Christine.abasi@utdallas.edu

John Hart Jr., MD

CONTACT

972-883-4832; jhart@utdallas.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: January 15, 2026
• First Posted: January 21, 2026
• Study Start: March 17, 2026
• Primary Completion (Estimated): August 30, 2026
• Study Completion (Estimated): September 30, 2026
• Last Updated: April 14, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will share
• Shared Documents: CSR
• Time Frame: IPD data will be available 3 months after publication
• Access Criteria: The Clinical Study Report (CSR) will be made available upon reasonable request. Researchers must submit a brief written request describing the purpose of accessing the CSR. Requests will be reviewed by the study team for appropriateness and compliance with institutional policies.

Locations

US (1)