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NCT Number: NCT07222163

Stuttering and Neuromodulation

The purpose of this study is to collect preliminary data on the efficacy of transcranial direct current stimulation (tDCS) combined with traditional behavioral techniques to reduce stuttering severity and negative impact in adults who stutter. The study also aims to explore neuroplastic changes (i.e., regional activation and functional connectivity) resulting from combined tDCS + speech therapy.

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Key information

Conditions

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

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

NYU Langone Health

New York, 10016, United States

Location status: Recruiting

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adults aged 18 to 65 years.
  • Diagnosis of developmental stuttering, verified by a licensed speech-language pathologist.
  • Mild-to-moderate or greater stuttering severity, defined as a score of 20 or higher on the Stuttering Severity Instrument-Fourth Edition (SSI-4).
  • English as a primary language.
  • Right-handedness (to minimize variability in neural lateralization).
  • Willing and able to attend all study sessions and follow study procedures.

Exclusion criteria

  • Have a history of neurological, psychiatric, or medical conditions that are contraindicated for tDCS.
  • Are currently taking medications known to affect cortical excitability.
  • Have a history of seizures or epilepsy.
  • Are pregnant or planning to become pregnant during the study period.
  • Have metal implants in the head (excluding dental work) or other contraindications to electrical brain stimulation.
  • Any skin disorder or skin sensitive area near stimulation locations.

Treatment and study plan

Soterix Medical 1x1 tDCS system

Device

Stimulation (2.0 mA for 30 minutes) will occur during speech therapy sessions focused on practicing speech techniques. Sham stimulation will mimic the physical sensation without active current.

Speech therapy sessions

Behavioral

Each of the ten weekly sessions will begin with 15 minutes of strategy practice, providing participants with the opportunity to rehearse light contact and easy onset techniques prior to the tDCS-enhanced speaking task.

Primary outcomes

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

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    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.

  2. Change in the Wright and Ayre Stuttering Self-Rating Profile (WASSP) score

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    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.

  3. Stuttering impact as assessed by the Overall Assessment of the Speaker's Experience of Stuttering - Adults (OASES-A)

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    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.

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

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    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.

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

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    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.

  6. Social Interaction Anxiety Scale (SIAS)

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    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.

Secondary outcomes

  1. Change in regional activation in/between cognitive control and speech motor areas during a delayed-naming task

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    Neuroplastic changes will be assessed using functional near-infrared spectroscopy (fNIRS) to measure cortical activation patterns (i.e., regional activation, functional connectivity) in/between cognitive control and speech motor areas during a delayed-naming task (pre- and post-intervention).

  2. Change in functional connectivity in/between cognitive control and speech motor areas during a delayed-naming task

    Time frame: Baseline, Visit 15 (~1-2 weeks post-intervention)

    Neuroplastic changes will be assessed using functional near-infrared spectroscopy (fNIRS) to measure cortical activation patterns (i.e., regional activation, functional connectivity) in/between cognitive control and speech motor areas during a delayed-naming task (pre- and post-intervention).

Study contacts

Contact information is provided by the study sponsor or research team.

Eric S. Jackson

CONTACT

[email protected]

212-992-9470

Sponsors and collaborators

Lead sponsor

NYU Langone Health

Other

Registry information

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Oct 29, 2025
Registry last updated
Oct 29, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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