Targeting Language-specific and Executive-control Networks With Transcranial Direct Current Stimulation in Logopenic Variant PPA

Part of paid clinical trials in Baltimore, Maryland.

Sponsor
Johns Hopkins University
Study ID
NCT03887481
Status
Recruiting
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Conditions

  • Logopenic Progressive Aphasia
  • Primary Progressive Aphasia

Eligibility Criteria

Sex
ALL
Age
50 Years - 80 Years
Healthy Volunteers
Accepted

Interventions

  • High-definition active tDCS (HD-tDCS) + "Repeat After Me" (RAM) Treatment — DEVICE
    Device: Active HD-tDCS \& "Repeat After Me" (RAM) Treatment Stimulation will be delivered by a battery-driven constant current stimulator. Electrical current will be administered to left supramarginal gyrus (L\_SMG). The stimulation will be delivered at an intensity of 2 milliamperes (mA) (estimated current density 0.04 mA/cm2; estimated total charge 0.048 Coulombs/cm2) in a ramp-like fashion for a maximum of 20 minutes. Participants will receive RAM consisting of word span repetition span (increasing length, with/without response delay). Span tasks will be manipulated in terms of list length (single words, pair, triplets) and response delay (1 sec, 5 sec). Each list will consist of 10 spans. During each trial, participants will be asked to repeat words in the span after a response delay.
  • Sham + "Repeat After Me" (RAM) Treatment — DEVICE
    Device: Sham Current will be administered in a ramp-like fashion but after the ramping phase the intensity will drop to 0 mA. Current under the Sham condition will last for a maximum of 30 seconds. Participants will receive RAM consisting of word span repetition span (increasing length, with/without response delay). Span tasks will be manipulated in terms of list length (single words, pair, triplets) and response delay (1 sec, 5 sec). Each list will consist of 10 spans. During each trial, participants will be asked to repeat words in the span after a response delay.

Study Details

AD afflicts over 5.5. million Americans and is one of the most expensive diseases worldwide. In AD the variant in which language functions are most affected are referred to as 'logopenic variant Primary Progressive Aphasia' (lvPPA). Language deficits dramatically impair communication and quality of life for both patients and caregivers. PPA usually has an early onset (50-65 years of age), detrimentally affecting work and family life. Studies have identified verbal short-term memory/working memory (vSTM/WM) as a primary deficit and cause of language impairment. In the first cycle of this award, the investigators asked the question of whether language therapy effects could be augmented by electrical stimulation. The investigators conducted the largest to-date randomized, double-blind, sham-controlled, crossover, clinical trial to determine the effects of transcranial direct current stimulation (tDCS) in PPA. The investigators found that tDCS over the left inferior frontal gyrus (L\_IFG), one of the major language hubs in the brain, significantly enhanced the effects of a written naming and spelling intervention. In addition, findings demonstrated that tDCS modulates functional connectivity between the stimulated area and other networks (e.g. functionally and structurally connected areas), and that tDCS modulates the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). In terms of tDCS, the investigators have been identified several predictors to determine the beneficience of tDCS including (a) PPA variant, (b) initial performance on cognitive/language tasks, particularly vSTM/WM, and (c) initial white-matter integrity and structure. These findings support the notion that tDCS benefits generalize beyond the treatment tasks and has led to the important question of the present study: How can we implement treatments to product benefits that maximally generalize to untrained but vital language/cognitive functions. To address the above question, the investigators will test recent neuroplasticity theories that claim that the benefits of neuromodulation to language-specific areas generalize to other language functions within the language network, while neuromodulation of a domain-general/multiple-demands area generalizes to both domain-general, executive and language functions. The two areas to be stimulated will be the supramarginal gyrus (SMG) and left dorsolateral prefrontal cortex (DLPFC) respectively. The left supramarginal gyrus (L\_SMG) in particular, specializes in phonological processing, namely phonological verbal short-term memory (vSTM), i.e., the ability to temporarily store phonological (and graphemic) information in order. The domain of vSTM affects many language tasks (repetition, naming, syntax), which makes it an ideal treatment target and the L\_SMG an ideal stimulation target, since generalization of tDCS effects to other language tasks is driven by the function (computation) of the stimulated area. By testing a fundamental principle of neuromodulation in a devastating neurodegenerative disorder, the investigators will significantly advance the field of neurorehabilitation in early-onset dementias. Aim 1: To determine whether vSTM/WM behavioral therapy combined with high definition (HD)-tDCS over the L\_SMG will induce more generalization to language-specific tasks than to executive tasks, whereas stimulation over the LDPFC will induce equivalent generalization to both executive and language-specific tasks. Aim 2: To understand the mechanism of tDCS by measuring tDCS-induced changes in network functional connectivity (FC) and GABA in the LSMG and LDPFC. The investigators will carry out resting-state functional magnetic resonance imaging (rsfMRI), (MPRAGE), diffusion-weighted imaging (DWI), perfusion imaging (pCASL), and magnetic resonance spectroscopy (MRS), before, after, and 3-months post-intervention. Aim 3: To identify the neural, cognitive, physiological, clinical and demographic characteristics (biomarkers) that predict sham, tDCS, and tDCS vs. sham effects on vSTM and related language tasks in PPA. The investigators will evaluate neural (functional and structural connectivity, cortical volume, neuropeptides, and perfusion), cognitive (memory, attention, executive) and language functions, clinical (severity), physiological (sleep), and demographic (age, gender) characteristics, and the investigators will analyze the effects on vSTM and other language/cognitive outcomes immediately after intervention and at 3 months post-intervention.

Key Dates

Start date
Oct 15, 2022
Status verified
Sep 2025
Primary completion
Oct 31, 2027
Completion
Oct 31, 2027

Study Design

Enrollment
60 participants (estimated)
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT

Arms

  • Experimental: Active HD-tDCS + Language/Cognitive Intervention(s) first
    Participants will receive active HD-tDCS + Language/Cognitive Intervention(s) first and then receive Sham + Language/Cognitive Intervention(s) after a three-month washout period.
  • Experimental: Sham + Language/Cognitive Intervention(s) first
    Participants will receive Sham + Language/Cognitive Intervention(s) first and then receive active HD-tDCS + Language/Cognitive Intervention(s) after a three-month washout period.

Primary Outcome Measure

Change in percent accuracy on word repetition (no delay) assessed by Temple Assessment of Language and Short-Term Memory in Aphasia (TALSA) Test 3 [ Time Frame: Before intervention, immediately after intervention, 1 month post intervention, 3 months post intervention ]

Central Contacts

Locations (1)

FacilityCityStateZIPSite coordinators
Johns Hopkins HospitalBaltimoreMaryland21287
Kyrana Tsapkini, PhD
[email protected]
410-736-2940
Kyrana Tsapkini, PhD (PRINCIPAL_INVESTIGATOR)

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