Recruiting

HD-tDCS

Sponsor:

The University of Texas at Dallas

Code:

NCT07354139

Conditions

Stuttering

Fluency Disorder

Eligibility Criteria

Sex: All

Age: 22+

Healthy Volunteers: Not accepted

Interventions

High - Definition Transcranial Direct Current Stimulation

Study Details

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. 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. Brain Stimulation: Participants will receive a session of targeted noninvasive brain stimulation (HD-tDCS).
3. 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

Study ID

NCT07354139

Start date

Mar 17, 2026

Status verified date

Apr, 2026

Completion date

Sep 30, 2026

Anticipated

Primary completion date

Aug 30, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 22+

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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
  • 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.

Study Design

Enrollment

50 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Left Inferior Frontal Gyrus

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

experimental: Presupplementary motor area

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.

Interventions

High - Definition Transcranial Direct Current 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

Primary outcome measure

  • Stuttering Severity Instrument - 4 [ Time Frame: Measured at singular clinical visit (baseline) ]
  • Predictive Naming Task [ Time Frame: Measured at singular clinical visit (baseline) ]

Central Contacts and Locations

Central contacts

Christine H Abasi, MS-SLP

8177187301Christine.abasi@utdallas.edu

John Hart Jr., MD

972-883-4832jhart@utdallas.edu

Locations

Callier Clinical Research Center

Recruiting

Richardson, Texas, United States, 75080

Contacts

Christine H Abasi, MS-SLP

817-718-7301christine.abasi@utdallas.edu

More Information

Sponsor

The University of Texas at Dallas

Last update posted

Apr 14, 2026

Last verified

Apr, 2026

Keywords

  • Stuttering
  • HD-tDCS
  • neuromodulation
  • speech
  • fluency

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by The University of Texas at Dallas on 2026-04-14.