Investigating Non-invasive Brain Stimulation to Enhance Fluency in People Who Stutter (INSTEP)

This study aims to test whether the application of transcranial direct current stimulation (tDCS) concurrent with fluency training results in improvements in speech fluency in adults with developmental stuttering, measured up to three months after the intervention.

Study Overview

• Status: Completed
• Conditions: Stuttering, Developmental
• Intervention / Treatment: Behavioral: Metronome-timed speech; Device: Active tDCS; Device: Sham tDCS

Detailed Description

Developmental stuttering affects 5% of children and persists to adulthood in about 1%. Changing the way speech is produced in adults who stutter is a particular challenge for speech and language therapy and there is a need for novel interventions. One such intervention involves the application of transcranial direct current stimulation (tDCS) alongside therapies aimed at improving speech fluency. tDCS influences brain activity by modulating neuronal plasticity through the application of weak electrical currents across the brain. Pairing tDCS with speech therapy has potential for producing larger or longer lasting effects and reducing time spent in therapy.

The study will evaluate the potential of tDCS combined with speech fluency training to improve outcomes in people who stutter (PWS). PWS will have this training while receiving tDCS for five days (1 milliampere [mA] for 20 mins per day) in a double-blind randomized controlled trial. Outcomes will be measured in terms of changes to stuttering severity.

An additional research questions is how changes in interactions between sensory and motor brain regions relate to changes in speech fluency in PWS. MRI will be used to measure brain structure and function and the vocal tract during speech production. Transcranial magnetic stimulation (TMS) will assess motor excitability before and after the training.

• Study Type: Interventional
• Enrollment (Actual): 43
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Oxford, United Kingdom, OX2 6BW
    • Department of Experimental Psychology, University of Oxford

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years to 43 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the study.
• Diagnosed with developmental stuttering of mild-moderate or greater severity
• Native speaker of English
• Normal or corrected-to-normal vision
• Normal hearing

Exclusion Criteria:

• Speech, language or communication disorder other than developmental stuttering.
• Contraindication to brain stimulation (tDCS or TMS)
• Contraindication to MRI
• History of drug abuse
• History of a neurological or psychiatric illness
• Any previous neurosurgical procedures
• Taking prescription or over-the-counter medication that may affect brain function (for example, anti-depressants)
• Family history of epilepsy (first degree relative)
• Severe claustrophobia (as they may be unable to tolerate scanner)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Active TDCS and Fluency Intervention; Participants will receive 1-milliamp (mA) tDCS with the anode (5 x 7 cm) placed over the left frontal cortex and the cathode (5 x 7 cm) placed symmetrically over the right frontal cortex. tDCS will be delivered using a direct current (DC) stimulator in 'study-mode' for 20 minutes a day for five consecutive days. he stimulation will be applied for the first half of a 40-minute speech fluency training paradigm, using metronome-timed speech.	Behavioral: Metronome-timed speech; Reading, narrative, and conversational speech tasks will be completed on each of the five intervention days. Metronome- timed speech will be practiced during these tasks, at near-normal (comfortable) speech rate for each participant. Each intervention session will be 40 minutes in duration.; Device: Active tDCS; 1-mA tDCS with the anode (5 x 7 cm) placed over the left frontal cortex and the cathode (5 x 7 cm) placed symmetrically over the right frontal cortex. tDCS will be delivered using a direct current (DC) stimulator in 'study-mode' for 20 minutes. The current is ramped up to 1 mA over the first 15 seconds of stimulation and maintained at this level for remainder of the 20-minute stimulation session.
Sham Comparator: Sham TDCS and Fluency Intervention; Participants will receive sham stimulation with the anode and cathode electrodes placed over the left and right frontal cortex as in the active arm. Sham stimulation will be delivered using a DC-stimulator in 'study-mode' for 20 minutes a day for five consecutive days. For sham stimulation, the current is ramped up over 15 seconds, maintained for 15 seconds at 1 mA and ramped down over 15 seconds at the start of stimulation and is then followed by brief (3ms) pulses every 55 seconds for the remainder of the 20-minute stimulation session. he stimulation will be applied for the first half of a 40-minute speech fluency training paradigm, using metronome-timed speech.	Behavioral: Metronome-timed speech; Reading, narrative, and conversational speech tasks will be completed on each of the five intervention days. Metronome- timed speech will be practiced during these tasks, at near-normal (comfortable) speech rate for each participant. Each intervention session will be 40 minutes in duration.; Device: Sham tDCS; Sham stimulation will be delivered using a DC-stimulator in 'study-mode' for 20 minutes. Participants will receive sham stimulation with the anode and cathode electrodes placed over the left and right frontal cortex as in the active arm. For sham stimulation, the current is ramped up over 15 seconds, maintained for 15 seconds at 1 mA and ramped down over 15 seconds at the start of stimulation and is then followed by brief (3ms) pulses every 55 seconds for the remainder of the 20-minute stimulation session.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Stuttering Severity Instrument (SSI-4) Score	The Stuttering Severity Instrument (SSI-4) is a standardised measure of stuttering severity comprised of 3 sub-scores (frequency, duration and physical concomitants) which are summed to give a total score. We will use change from baseline in total score (i.e. baseline subtracted) on the Stuttering Severity Instrument version 4 measured post intervention. The maximum total score of the SSI-4 is 56, which corresponds to the highest stuttering severity. Therefore, larger negative change scores represent better outcomes (larger reductions in stuttering severity).	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in percentage of disfluent syllables produced during conversation	Change from baseline (i.e. baseline subtracted) in percentage of disfluent syllables produced during a two-minute conversation sample. Larger negative change scores represent better outcomes (larger reductions in frequency of disfluency).	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention
Change in percentage of disfluent syllables produced during reading	Change from baseline (i.e. baseline subtracted) in percentage of disfluent syllables produced during a two-minute reading sample. Larger negative change scores represent better outcomes (larger reductions in frequency of disfluency).	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention
Change in Overall Assessment of the Speaker's Experience of Stuttering (OASES) score	The Overall Assessment of the Speaker's Experience of Stuttering (OASES) is a standardised self-assessment to measure the effect of stuttering on a person's life, comprising of 4 sub-scores (general information about speech, your reactions to stuttering, communication in daily situations, quality of life). The total score (out of a possible 500) is divided by the number of items (out of a possible 100. Note that some items may not apply to all participants). This gives a total impact score between 1 and 5, with 5 representing the highest negative impact on person's life. We will use change from baseline in total score (i.e. baseline subtracted) on the OASES total impact score, measured post intervention, as an outcome. Larger negative change scores represent better outcomes (larger reductions in negative impact of stuttering ).	6 weeks and 12 weeks after the end of the 5-day intervention

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Premonitory Awareness in Stuttering Scale	Change in total score on measure of anticipation of stuttering	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention
Change in Beck Anxiety Inventory	Change in total score on the Beck Anxiety Inventory	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention
Change in Subjective rating of stuttering severity	Change in self-rating on 9 point scale	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention
Change in Subjective rating of speech naturalness	Change in self-rating on 9 point scale	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention
Change in Objective rating of stuttering severity	Change in Researcher rating on 9 point scale	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention
Change in Objective rating of speech naturalness	Change in Researcher rating on 9 point scale	1 week, 6 weeks and 12 weeks after the end of the 5-day intervention

Collaborators and Investigators

• Sponsor: University of Oxford
• Investigators: Principal Investigator: Kate E Watkins, PhD, University of Oxford

Publications and helpful links

Helpful Links

• INSTEP trial website
• Speech and Brain Research Group website

Study record dates

Study Major Dates

• Study Start (Actual): November 15, 2017
• Primary Completion (Actual): June 1, 2020
• Study Completion (Actual): June 1, 2020

Study Registration Dates

• First Submitted: October 26, 2017
• First Submitted That Met QC Criteria: November 3, 2017
• First Posted (Actual): November 8, 2017

Study Record Updates

• Last Update Posted (Actual): May 18, 2022
• Last Update Submitted That Met QC Criteria: May 17, 2022
• Last Verified: May 1, 2022

More Information

Terms related to this study

• Keywords: stammering; speech motor disorder; electrical current stimulation; metronome-timed speech
• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Neurobehavioral Manifestations; Language Disorders; Communication Disorders; Speech Disorders; Stuttering
• Other Study ID Numbers: R52173/RE001_

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No