Combining tDCS and CILT in Non-fluent Aphasia

The long-term goal of this work is to determine if combining a highly intensive, task-specific behavioral language intervention with modulation of the efferent cerebellar-cortical pathway using transcranial direct current stimulation (tDCS) has a positive influence on discourse, verbal fluency and working memory in individuals with non-fluent aphasia after stroke. And if these changes can be related to neuroplastic change in the cerebellar cortical pathway indirectly measured through neurophysiologic changes using spectral electroencephalogram (EEG). The initial phase includes the proposed pilot study data from which will be used to inform a larger clinical trial. The primary aims of this pilot are to 1) determine the effect of combining cerebellar tDCS with constraint-induced language therapy (CILT) on language as measured by a verbal fluency task and discourse task in a small population and 2) identify the tolerance of the intervention and barriers to participation measured by the adverse events questionnaire that will inform the methodology of a larger study. The secondary aims include estimating the size of the treatment effect on 1) delta percentage in F3, F7 and Fp1 compared to F4, F8, and Fp2 using resting state EEG spectral analysis and coherence, 2) working memory as measured by the score on the n-back test and 3) quality of life as measured by the Stroke Aphasia Quality of Life survey tool. The secondary aims will be used to determine the utility of these measures in a larger clinical trial.

This is a prospective, crossover study, sham-controlled intervention study with two intervention conditions delivered across 6 intervention sessions (3x/week for two weeks) with a 4-week washout in between. Conditions include: 1) sham cerebellar tDCS and 2) real cerebellar tDCS delivered at 2mA across 20 minutes. Each of these will be delivered during CILT intervention with a licensed, certified speech-language pathologist trained in CILT. Once tDCS stimulation has ended, CILT will continue to be delivered for an additional 25 minutes. Assessments of discourse, verbal fluency, working memory and EEG spectral analysis will be conducted at four timepoints, before and after each intervention phase.

This is a prospective sham-controlled, cross-over design. Eligible participants must be over the age of 18 years, be \> least 6 months post unilateral cortical stroke and diagnosed with mild to moderate non-fluent aphasia. Additional inclusion/exclusionary criteria have been specified in and approved by the IRB. Six to seven participants are expected to be recruited and screened, with the goal to enroll and complete the study with four individuals who will be randomly assigned to receive either sham or real condition first. The two intervention conditions include: 1) andodal tDCS (2mA) to the right posterior-lateral cerebellum and 2) sham tDCS to the right posterior-lateral cerebellum. The participants will receive 20 minutes of tDCS (sham or real) during CILT followed by an additional 25 minutes of CILT alone. Each condition will be administered 3 days per week for two weeks for a total of 6 intervention sessions with a 4-week washout period between.

For tDCS (TCT-Research Version tDCS Stimulator, Hong Kong), two 5x5 saline-soaked sponge electrodes will be used with the anode placed over the right cerebellar hemisphere; 1cm under and 4cm lateral of the inion targeting the posterior lateral cerebellum and the cathode will be placed on the right shoulder. The electrode placement will be the same across both conditions. The CILT behavioral intervention will be led by a certified, licensed speech-language pathologist and a graduate student researcher and will follow the guidelines of CILT.

Eligibility Criteria:
Inclusion Criteria:

* over the age of 18 years
* history of stroke
* diagnosed with non-fluent aphasia.
* be able to independently understand simple directions,
* use some speech to communicate,
* have access to reliable transportation (including taxi and/or other transportation services),
* fluent in English.

Exclusion Criteria:

* Pregnancy,
* history of seizures,
* any metal implants in the body (excluding dental fillings),
* history of migraines,
* psoriasis or eczema affecting the scalp,
* history of a head injury such as a concussion
* diagnosis of a mental health or neurological condition/disease.