Non-invasive Brain Stimulation in Adults Who Stutter

Recruitment & Eligibility

Inclusion Criteria

history of persistent developmental stuttering
stuttering severity ranging from mild to very severe, specifically Stuttering Severity Instrument (SSI) total score of 20 (mild) or higher and stuttering rates of 3% or higher
scores within 1 standard deviation of the norm on the standardized tests for the study

Exclusion Criteria

received any treatment for stuttering within the past year
other neurological conditions such as Tourette's syndrome or post-traumatic stress disorder
taking any medications/drugs that affect brain function
history of past or current mental illness for example, schizophrenia that may affect brain development and function
history of serious medical or neurological illness such as epilepsy and Parkinson's disease
history of closed head injury (e.g., concussion)
history of reading disorders
hearing loss
taking any medication, prescription or non-prescription with any psychotropic effects at the time of the study
metal or electronic implants such as cochlear implants, and pacemakers

Study & Design

Arm && Interventions

Group	Intervention	Description
Active tDCS and fluency training	Anodal tDCS	Participants will receive anodal tDCS at 2milliampere (mA) intensity for 20 minutes during speech fluency training (5 consecutive days).
Active tDCS and fluency training	Fluency training	Participants will receive anodal tDCS at 2milliampere (mA) intensity for 20 minutes during speech fluency training (5 consecutive days).
Sham tDCS and fluency training	Fluency training	Participants will receive sham tDCS. Sham stimulation will involve 30 seconds of stimulation at the beginning of the 20 minutes of speech fluency training (5 consecutive days).
Sham tDCS and fluency training	Sham tDCS	Participants will receive sham tDCS. Sham stimulation will involve 30 seconds of stimulation at the beginning of the 20 minutes of speech fluency training (5 consecutive days).

Primary Outcome Measures

Name	Time	Method
Change in Percentage of Stuttered Syllables Produced During Speech Sample	Baseline, 1 week (post), 4 weeks (follow up)	Investigators 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).
Changes in Brain Activation as Assessed by fMRI Images	Baseline, 1 week (post), 4 weeks (follow up)	Investigators will use the fMRI images taken from before and after tDCS to determine if the treatment intervention contributed to any changes within brain regions associated with speech production. This will be measured by Blood-Oxygen-Level-Dependent (BOLD) signal change (arbitrary units). Images from scans are preprocessed. Changes in BOLD signal are modeled for contrasts within a group for \[post-pre\] and \[follow up-pre\] (e.g., active group reading condition post visit MINUS active group reading pre visit). Results are reported for reading condition.

Secondary Outcome Measures

Name	Time	Method
Changes From Baseline on the Overall Assessment of Speakers Experience of Stuttering (OASES)	Baseline, 1 week (post), 4 weeks (follow up)	The OASES is a standardized assessment of the functional impact of stuttering on a person's life. There are 4 sub-tests: general information about speech, your reactions to stuttering, communication in daily situations, quality of life. Each one has a score from 1 to 5 with regard to impact (1 least, 5 most negative impact). These are combined to give a total impact score between 1 and 5, with 5 representing the highest negative impact on person's life. The change on the total impact score will be used. Changes are shown in the table below by comparison between the measurements at the three points in time.

Recruitment & Eligibility