An interventional study of tACS in Aphasia and Stroke, sponsored by Medical College of Wisconsin. Recruiting at 1 site in United States. Open to participants aged 18 Years to 85 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-29.
Sponsored by Medical College of Wisconsin · Not applicable, Interventional, and Treatment
This study will assess the effects of transcranial alternating current stimulation (tACS) on language recovery after stroke as well as healthy language functions.
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 (NIH-NIDCD, 2015). 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 by providing 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 aphasia. TACS differs from widely used transcranial direct current stimulation (tDCS) in that sinusoidal, alternating currents are delivered rather than constant currents. TACS can manipulate the ongoing oscillatory neuronal activity and potentially increase functional synchronization (or connectivity) between targeted areas. This feature of tACS is quite attractive, given the new body of evidence suggesting that language impairments stem from diminished functional connectivity and disruptions in the language network due to stroke. The selection of tACS frequencies in this study is guided by our preliminary work examining pathological neural oscillations found near stroke-lesioned areas (or perilesional) in aphasia and by the involvement of specific frequencies during a verbal short-term memory task. By exogenously tuning the neural oscillations with tACS, the investigators hope to up-regulate communication across regions within the language network and other connected areas to improve outcomes. If successful, tACS will be a powerful and novel treatment approach with reverberating positive impact on long-term recovery.
The study will employ HD-tACS in a within-subject and sham-controlled design, using frequencies ranging from theta to low-gamma (4-40 Hz) combined with language tasks. Magnetoencephalography (MEG) or electroencephalography (EEG) will be used to determine tACS frequencies and to evaluate behavioral and neurophysiological changes in response to tACS. Investigators plan to recruit 200 participants: 100 stroke survivors with aphasia and 100 healthy controls.
Participants will complete language testing that covers a broad range of language functions, medical history, and MRI. Eligible participants will undergo active tACS or sham-tACS over 3-4 sessions. The tACS administrator and participants will be blinded to the stimulation type. The order of stimulation type will be counterbalanced across participants. Washout period between visits will be at least 48 hours to minimize potential carryover effects. MEG will be collected prior to tACS sessions during a language task to determine tACS frequency. EEG may be acquired before and after tACS during periods of rest (resting-state) and during language tasks. Participants will complete a questionnaire at the end of stimulation visits to assess potential side effects of tACS. Total time enrolled in the study is expected to be 2-3 weeks, which may be longer depending on participant's availability.
338 studies on the registry are indexed under Aphasia; 95 are open to participants now.
This study's planned enrollment of 50 is above the median of 30 across 298 interventional studies indexed under Aphasia.
Browse Aphasia studies →Medical College of Wisconsin is the lead sponsor of 548 studies on the registry; 122 are open to participants now.
Of its 75 completed or terminated interventional studies of FDA-regulated products, 57 (76%) have results posted.
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Healthy Controls
Stroke Patients
Exclusion Criteria:
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A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Contraindication
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All participants in a within-subject design will receive high-Definition-tACS, delivered via a battery operated alternating current stimulator (Soterix) using two 3x1 center-surround montages. Targets of stimulation will be localized based on the 10-10 International EEG system or fMRI-guided targets with center electrodes placed at a frontal/anterior and a temporoparietal/posterior site. The current is turned on and increased in a ramplike fashion over approximately 30 seconds. Participants will undergo tACS with frequencies ranging from 4-40Hz for 20-minutes with 2 milliampere (mA) peak-to-peak intensity. For sham stimulation, tACS is turned off after the first 30 seconds.
Device: tACS
Active or Sham tACS will be applied.
tACS changes in language performance verbal STM tasks
Improvement on verbal STM performance as determined by increases in span, accuracy or decreases in reaction time is expected with active tACS.
Time frame: Changes monitored over pre, during and immediately after 20 minutes of tACS
tACS-dependent neurophysiological changes
Concomitant frequency-specific EEG changes in spectral power and phase synchronization are expected.
Time frame: Changes monitored over pre and immediately after 20 minutes of tACS
Individual differences in tACS responsiveness
tACS responsiveness depending on language impairment types, stroke lesion and language lateralization characteristics will be explored.
Time frame: Based on immediate changes monitored after 20 minutes of tACS
Plan to share: No
Started Jan 2020 (actual). Primary completion is estimated for Jan 2030, 120 months after the start.
Of 183 non-industry interventional studies with no phase under Aphasia, half reached primary completion within 36 months of starting (the median), counting those still running; a quarter within 19 and three quarters within 57. This study's planned 120 months is above that.
Counting every sponsor, half of 185 studies reached it within 36 months; a quarter within 20 and three quarters within 57.
How these figures are worked out, and which studies are left out of them.
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