Transcranial Alternating Current Stimulation (tACS) in Stuttering

University of Michigan80 enrolled

Overview

The purpose of this study is to investigate how mild, noninvasive electrical brain stimulation affects speech relevant brain areas, which may in turn affect speech fluency and speaking-related brain activity in people that stutter. The long-term goal of this study is to test the therapeutic potential of transcranial alternating current stimulation (tACS) for the treatment of stuttering. The study team hypothesizes that if stuttering involves impaired initiation of motor programs, delta-tuned tACS will strengthen communication between brain regions and decrease stuttering. Therefore, delta-tuned sensorimotor tACS will be paired with fluency-induced speech (choral reading), which is hypothesized to decrease stuttering via improved auditory motor integration.

Participants will have screening and baseline visits that include a variety of tests and procedures (i.e. standardized tests of speech, language, hearing test, music training questionnaire, working memory tests, and speech sample to characterize stuttering, magnetic resonance imaging (MRI) and electroencephalography (EEG)). Following these, participants will have 3 sessions (active and sham conditions) and then a one month follow-up phone or video call. Of note, there will be an embedded pilot study to refine the experimental protocol in terms of practicality and feasibility and these participants will not be included in this registration. The only purpose of this embedded study is to refine the protocol and it does not have any health or behavioral outcomes.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Enrollment

Conditions

Interventions

transcranial alternating current stimulation (tACS)DEVICE

During each of the 3 stimulation visits, participants will be seated in a comfortable position and a cap will be placed on participant's head similar to a swimming cap. Small electrodes will be placed near the surface of the scalp at certain regions of interest, and a weak electrical current will be passed through the electrodes into speech related brain areas for 20 minutes. The study team will not use current strengths exceeding 2 milliamps (mA).

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 Years

Medical Language ↔ Plain English

Inclusion Criteria for stutterers: * Have normal language, hearing, and cognition * Speak English as the primary language * Currently stutter * Score (per protocol) a certain value on the Stuttering Severity Instrument (SSI-4). * Have not received any treatment for stuttering within the past year Exclusion Criteria for stutterers: * History of seizures * Major medical or neurological illness (e.g., stroke, serious head trauma, brain infection, Parkinson's disease, etc.) * History of closed head injury with loss of consciousness (e.g., concussion) * Metal or electronic implants such as cochlear implants and pacemakers anywhere in the body * Braids or other hair styling that prevents direct access to the scalp (if removal not possible) * Currently pregnant

Outcomes

Primary Outcomes

Change in Phase Synchronization

The study will compare EEG data recorded before and after stimulation to determine if tACS contributed to any changes. This will be measured by Phase Locking Value (PLV; measured from 0 to 1) between the two regions targeted by stimulation calculated as \[pre(active-sham)\] - \[post(active-sham)\] at each tACS visit.

Time frame: Baseline (pre-tACS), approximately 3 hours (post-tACS) (visits 3-5)

Secondary Outcomes

Percentage of stuttered syllables produced during speech sample

The study will calculate the percentage of stuttered syllables (out of total syllables) in a speech sample. Decreased stuttered syllables represents better outcomes (greater reduction in stuttering).

Time frame: Baseline (before tACS), approximately 3 hours (post-tACS) (visits 3-5)