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

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

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.

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.

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)