Investigating Non-invasive Brain Stimulation to Enhance Fluency in People Who Stutter
Condition: Stuttering, Developmental
MeSH terms: Stuttering
Study type: Interventional

Summary: 
      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.
    

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.
    

Intervention name(s): Metronome-timed speech; Active tDCS; Sham tDCS
Intervention type(s): Behavioral; Device; Device
Intervention description(s): 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.; 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 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.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Double-blind, placebo-controlled (sham tDCS), randomised trial, with 20 participants with developmental stuttering recruited for each of the two arms of the trial.
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: stammering; speech motor disorder; electrical current stimulation; metronome-timed speech