Transcranial Alternating Current Stimulation (tACS) for the Recovery of Phonological Short-Term Memory in Patients With Aphasia After Stroke

Official title

TACS for the Recovery of Phonological STM After Stroke

Overview

This study will assess the effects of transcranial alternating current stimulation (tACS) on language recovery after stroke.

Detailed description

Aphasia is a debilitating disorder, typically resulting from damage to the left hemisphere, that can impair a range of communication abilities, including language production and comprehension, reading, and writing. Approximately 180,000 new cases of aphasia are identified per year, and approximately 1 million or 1 in 250 are living with aphasia in the United States. Treatments are limited and provide modest benefits at best. The current emphasis in aphasia rehabilitation is to formulate intensive speech and language therapies and augment therapeutic benefits, potentially with brain stimulation concurrent with therapies.

The current study will investigate the efficacy of high-definition tACS (HD-tACS) to help restore neural oscillatory activity in stroke survivors with aphasia. TACS differs from trancranial direct current stimulation (tDCS), a widely used brain stimulation paradigm, in that sinusoidal or alternating currents are delivered rather than direct currents. TACS is shown to manipulate ongoing oscillatory brain activity and also to modulate synchronization (or connectivity) between targeted brain areas. This feature of tACS is quite attractive, given the new body of evidence suggesting that language impairments stem from diminished brain connectivity and ensuing disruptions in the language network due to stroke.

The study will employ high-definition tACS (HD-tACS) in a parallel, double-blinded, sham-controlled design combined with language therapy targeting phonological short-term memory (STM) function in stroke survivors with aphasia. Magnetoencephalography (MEG) and fMRI BOLD data collection will occur to determine tACS parameters and to evaluate stimulation-induced neural changes, respectively. The investigators plan to recruit 120 stroke survivors with aphasia in a 2-group tACS study design.

Interventions

• Device HD-tACS
  High definition tACS will be applied during speech therapy.
• Device Sham HD-tACS
  Sham high definition tACS will be applied during speech therapy.

Primary outcome measures

• Accuracy on a phonological STM task [Time frame: Upon the completion of therapy cycle (a cycle consists of 10 intervention days) and 10 weeks post]
• fMRI measures of language network activation after tACS [Time frame: Upon the completion of therapy cycle (a cycle consists of 10 intervention days) and 10 weeks post]

Secondary outcome measures (1)

• Functional Communication Outcome [Time frame: Upon the completion of therapy cycle (a cycle consists of 10 intervention days) and 10 weeks post]

Eligibility criteria

Inclusion criteria

• Diagnosed with left hemisphere stroke/aphasia
• Consent date >= 1 month after stroke onset
• Fluent in English
• 18 years of age or older

Exclusion criteria

• Severe cognitive, auditory or visual impairments that would preclude cognitive and language testing
• Presence of major untreated or unstable psychiatric disease
• A chronic medical condition that is not treated or is unstable
• The presence of cardiac stimulators or pacemakers
• Contraindications to MRI or tACS, e.g. patients with metallic implants, and/or history of skull fractures, pregnancy, skin diseases
• History of ongoing or unmanaged seizures
• History of dyslexia or other developmental learning disabilities

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Triple blind

Primary purpose

Treatment

Study locations

United States · 1 center

• Medical College of Wisconsin — Milwaukee

Publications

• Pedersen PM, Jorgensen HS, Nakayama H, Raaschou HO, Olsen TS. Aphasia in acute stroke: incidence, determinants, and recovery. Ann Neurol. 1995 Oct;38(4):659-66. doi: 10.1002/ana.410380416. PMID 7574464
• Engelter ST, Gostynski M, Papa S, Frei M, Born C, Ajdacic-Gross V, Gutzwiller F, Lyrer PA. Epidemiology of aphasia attributable to first ischemic stroke: incidence, severity, fluency, etiology, and thrombolysis. Stroke. 2006 Jun;37(6):1379-84. doi: 10.1161/01.STR.0000221815.64093.8c. Epub 2006 May 11. PMID 16690899
• Shah-Basak PP, Norise C, Garcia G, Torres J, Faseyitan O, Hamilton RH. Individualized treatment with transcranial direct current stimulation in patients with chronic non-fluent aphasia due to stroke. Front Hum Neurosci. 2015 Apr 21;9:201. doi: 10.3389/fnhum.2015.00201. eCollection 2015. PMID 25954178
• Shah-Basak PP, Wurzman R, Purcell JB, Gervits F, Hamilton R. Fields or flows? A comparative metaanalysis of transcranial magnetic and direct current stimulation to treat post-stroke aphasia. Restor Neurol Neurosci. 2016 May 2;34(4):537-58. doi: 10.3233/RNN-150616. PMID 27163249
• Boyle M. Semantic feature analysis treatment for anomia in two fluent aphasia syndromes. Am J Speech Lang Pathol. 2004 Aug;13(3):236-49. doi: 10.1044/1058-0360(2004/025). PMID 15339233
• Leonard, C., Rochon, E., & Laird, L. (2008). Treating naming impairments in aphasia: Findings from a phonological components analysis treatment. Aphasiology, 22, 923-947. https://doi.org/10.1080/02687030701831474
• Paulesu E, Frith CD, Frackowiak RS. The neural correlates of the verbal component of working memory. Nature. 1993 Mar 25;362(6418):342-5. doi: 10.1038/362342a0. PMID 8455719
• Buchsbaum BR, Olsen RK, Koch P, Berman KF. Human dorsal and ventral auditory streams subserve rehearsal-based and echoic processes during verbal working memory. Neuron. 2005 Nov 23;48(4):687-97. doi: 10.1016/j.neuron.2005.09.029. PMID 16301183

Identifiers

NCT: NCT06048159 · PRO00046360 · PRO00046360

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗