High-definition tDCS Treatment for Cantonese-speaking Adults Who Stutter

Not Applicable

Completed

Brief Summary: The proposed study aims to investigate the effect of combined transcranial direct current stimulation (tDCS) and behavioural speech training in improving speech fluency in Cantonese-speaking adults who stutter (AWS), and to examine its maintenance over a 6-week period.

Detailed Description: The proposed study aims to

1. assess the effect of multiple sessions of tDCS over the supplementary motor area (SMA) combined with behavioural speech training on stuttering recovery in terms of a reduction of stuttering severity and increased speech satisfaction in Cantonese-speaking AWS;

2. investigate the maintenance of combined tDCS-behavioural speech training effects on speech fluency and speech satisfaction in Cantonese-speaking AWS over a 6-week period.

Twenty Cantonese-speaking AWS will be randomly assigned to an experimental group and a control group. Both groups will receive behavioral treatment for stuttering, including the speech prolongation technique, for five sessions. Concurrent with behavioural training, the experimental group will receive anodal tDCS (1 mA for 20 minutes), while the control group will receive sham tDCS (1 mA for one minute), over the SMA. Stuttering severity and speech satisfaction will be assessed independently before, immediately after, one week and six weeks after treatment. It is anticipated that AWS will experience reduction in their stuttering severity after stimulation, and the improvement will be maintained for a longer period as compared with receiving behavioural treatment alone.

Recruitment & Eligibility

Inclusion Criteria

Demonstrated features of stuttering;
More than 2% of syllables stuttered over three baseline speech samples, as measured by qualified speech therapists.

Exclusion Criteria

Personal or family history of epilepsy or seizures
History of a neurological condition
Speech disorders
Hearing impairment
Metallic foreign body implant
On medications that lower neural thresholds (e.g. tricyclines, antidepressants, neuroleptic agents, etc.)
Pregnant
Had speech therapy for stuttering in the past four months

Arm && Interventions

Group	Intervention	Description
Sham tDCS	Sham-tDCS	The control group will only receive one minute of anodal HD-tDCS stimulation which aims to create a similar sensation on the scalp as those in the experimental group, with 20 minutes of behavioural therapy.
Active tDCS	Active-tDCS	The experimental group will receive 20 minutes of anodal HD-tDCS for five sessions, combined with 20 minutes of behavioural therapy.

Primary Outcome Measures

Name	Time	Method
Stuttering severity [Severity rating (SR)]	Change before, immediately after, one week and six weeks after treatment	The subjects will be trained to rate their own stuttering severity based on a 9-point SR scale, with 0 = no stuttering, 1 =very mild stuttering, and 8 = the most severe stuttering.
Stuttering severity [Percent syllables stuttered (%SS)]	Change before, immediately after, one week and six weeks after treatment	%SS is based on the proportion of spoken syllables that a judge perceives to be stuttered. It will be measured by a qualified speech therapist with prior training in stuttering assessment in Cantonese who will be blinded to the treatment conditions. To establish inter-rater agreement, 20% of the speech samples across different assessment data points will be randomly selected and rated by a second speech therapist.

Secondary Outcome Measures

Name	Time	Method
Subject satisfaction	One week and six weeks after treatment	For the assessment of subject satisfaction regarding the treatment, the following two Likert-type survey questions will be asked: 1. How much do you think the treatment helped you to speak more fluently? (1 = not at all, 2 = a little, 3 = somewhat, 4 = a lot, 5 = totally); and 2. How often/much do you think the treatment helped you to feel less stressed in your communication? (1 = never or not at all, 2 = rarely or a little, 3 = sometimes or somewhat, 4 = often or a lot, 5 = always or totally).