# The effects of transcranial direct current stimulation and fluency shaping techniques on enhancing speech fluency in adults who stutter: Protocol for a double-blind randomized controlled trial

## TL;DR

This study tests if combining brain stimulation with speech therapy improves fluency in adults who stutter.

## Contribution

The novel contribution is evaluating the combined effect of tDCS and fluency shaping techniques on stuttering.

## Key findings

- Combining tDCS with fluency shaping may reduce stuttering severity more than therapy alone.
- Long-term improvements in speech fluency and quality of life are expected.
- Outcomes will be measured using stuttered syllable ratio and self-reported experience assessments.

## Abstract

Stuttering is a condition that usually begins in childhood and may continue into adulthood. In this study, it is suggested that the combined approach of transcranial direct current stimulation (tDCS) with fluency shaping techniques will result in greater improvements in speech fluency compared to using fluency shaping techniques alone.

This study is designed as a randomized, double-blind, sham-controlled clinical trial. All participants will participate in speech therapy sessions. The intervention group will receive anodal transcranial direct current stimulation, while the control group will experience sham stimulation. Participants will be randomly assigned to one of these groups. Before starting the treatment program, a preintervention assessment will be conducted to determine the severity of stuttering. Once these assessments are completed, each participant will take part in intervention sessions. Post-intervention evaluations will take place immediately after and six weeks after the final intervention session. Additionally, to evaluate the long-term stability of the treatment results, follow-up evaluations will be carried out three months post-treatment. The primary outcome measure—the ratio of stuttered syllables—will be evaluated during pre-, post-, and follow-up assessments; secondary outcomes will encompass scores from the Overall Assessment of the Speaker's Experience of Stuttering, severity ratings, and evaluations of speech naturalness.

The results of this study will provide evidence regarding the effectiveness of combining tDCS with fluency shaping intervention on stuttering. This effect is likely to involve not only a reduction in SS% but also improvements in the overall quality of life for adults who stutter.

IRCT20230907059369N1.

•This study aims to examine the effects of anodal transcranial direct current stimulation (tDCS) on enhancing speech fluency in adults who stutter.•A double-blind, randomized controlled trial will be conducted to measure changes in stuttering severity following anodal transcranial direct current stimulation.•Sixty-two adults who stutter will be recruited to receive either anodal or sham transcranial direct current stimulation over the inferior frontal gyrus, combined with fluency shaping techniques.

This study aims to examine the effects of anodal transcranial direct current stimulation (tDCS) on enhancing speech fluency in adults who stutter.

A double-blind, randomized controlled trial will be conducted to measure changes in stuttering severity following anodal transcranial direct current stimulation.

Sixty-two adults who stutter will be recruited to receive either anodal or sham transcranial direct current stimulation over the inferior frontal gyrus, combined with fluency shaping techniques.