Effects of Transcranial Direct Current Stimulation (tDCS) on Brain Organization and Naming in Aphasic Patients.

April 28, 2026 updated by: Adrian Guggisberg

Effects of Transcranial Direct Current Stimulation (tDCS) on Brain Organization and Naming

High-Definition Transcranial Direct Current Stimulation (HD-tDCS) allows to induce, in a non-invasive way, a transient inhibitory or excitatory neuromodulation of a given cerebral region and to obtain a very focused cortical effect. Previous studies using HD-tDCS have shown the effectiveness of this stimulation technique for enhancing language recovery in patients with aphasia.

However, language processes are not determined solely by local neural activity at a single site, but rather by the interaction between neural networks. This is because a large cortical network is involved in language processes and, therefore, the same language disorder may result from lesions at different locations in this network.

The investigators hypothesize that anodal HD-tDCS will enhance neural interactions between language areas and, thereby, improve language processing and word learning.

The investigators propose to carry out a study on chronic aphasic patients involving HD-tDCS of the Broca region (left inferior frontal gyrus) combined with a verb learning task.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Functional connectivity (FC) represents a means of analyzing functional interactions in the brain network by assessing the statistical dependence of neural activity between brain areas. The brain maintains a high level of interactions between brain areas even in the resting state, when it is not explicitly involved in a specific task. Resting-state interactions occur mainly in the so-called alpha frequency band (8-13 Hz) . Moreover, these resting-state interactions are crucial for correct task performance and learning. Indeed, healthy subjects with high resting-state alpha-band FC levels are better able to perform tasks and learn. For example, subjects with high levels of FC between Broca's area and the rest of the brain perform better on language production tasks and show greater training gains when learning new words. In addition, patients with brain damage due to stroke show a reduction in resting-state alpha-band FC, which correlates with the severity of neurological deficits. In particular, a loss of FC of structurally preserved inferior frontal areas was associated with more severe aphasia. Conversely, high-levels of FC between the inferior frontal brain areas and the rest of the brain during the first weeks after stroke was associated with better recovery from aphasia, probably reflecting a reorganization of neural connections as a neural mechanism involved in plasticity. Resting-state FC is therefore an interesting neural target for therapy, which could help improve recovery from aphasia.

In a previous study on healthy subjects, the investigators have indeed observed that HD-tDCS applied to Broca's area improves the ability for new-verb learning, i.e., the correct naming of action pictures. This improvement in learning correlated with greater increase in FC between Broca's and Wernicke's area.

The investigators now carry out a study on chronic aphasic patients involving HD-tDCS of the Broca region (left inferior frontal gyrus) combined with a verb learning task.

Study Type

Interventional

Enrollment (Actual)

14

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Switzerland
    • Canton of Geneva
      • Geneva, Canton of Geneva, Switzerland, 1211
        • Division of Neurorehabilitation, University Hospital of Geneva

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Ischemic or hemorrhagic stroke
  • Presence of aphasia with difficulty finding words and/or naming objects/pictures
  • ≥12 months post-stroke
  • ≥ 18 years of age
  • French-speaking
  • Able to participate in 30-60 min therapeutic sessions (good concentration and understanding of the task and ability to follow instructions

Exclusion Criteria:

  • Patients unable to understand the given information on the study and its objectives, or instructions for tasks performed.
  • Impaired alertness or delirium
  • Severe co-morbidity affecting speech
  • Contraindication to tDCS: pregnant women, patients with active implants such as pacemakers or cochlear implants, patients with one or more seizures, metal objects in the brain
  • Occurrence of a new stroke during the study protocol.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: HD-tDCS
high-density transcranial direct current stimulation (HD-tDCS) over Broca's area
Device: HD-tDCS
The anode electrode will be placed over Broca's area, 4 cathode electrodes will be placed at about 2 cm distance each from the anode in 4 directions.
Other Names:
  • high-density transcranial direct current stimulation
  • DC-stimulator
Sham Comparator: sham-tDCS
sham transcranial direct current stimulation. The same setup will be used as in the HD-tDCS arm, except that the current will be ramped up for 30 seconds and then switched off. This does not lead to neural effects, but the patients have a similar sensation.
Device: HD-tDCS
The anode electrode will be placed over Broca's area, 4 cathode electrodes will be placed at about 2 cm distance each from the anode in 4 directions.
Other Names:
  • high-density transcranial direct current stimulation
  • DC-stimulator

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Action picture naming, short-term improvement
Time Frame: Change from day 1 (baseline) to day 5 (posttest)
Change in number of correctly named action pictures
Change from day 1 (baseline) to day 5 (posttest)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Functional connectivity between Broca's and Wernicke's area
Time Frame: Change from day 1 (baseline) to day 5 (posttest)
Change in the normalized imaginary component of coherence between Broca and Wernicke
Change from day 1 (baseline) to day 5 (posttest)

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Action picture naming, long-term improvement
Time Frame: Change from day 1 (baseline) to week 4 (follow-up)
Change in number of correctly named action pictures
Change from day 1 (baseline) to week 4 (follow-up)
Narrative speech, short-term improvement
Time Frame: Change from day 1 (baseline) to day 5 (posttest)
Patient describes cookie-theft picture and action-picture, change in score
Change from day 1 (baseline) to day 5 (posttest)
Narrative speech, long-term improvement
Time Frame: Change from day 1 (baseline) to week 4 (follow-up)
Patient describes cookie-theft picture and action-picture, change in score
Change from day 1 (baseline) to week 4 (follow-up)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Adrian Guggisberg

Investigators

  • Principal Investigator: Adrian G Guggisberg, MD, University of Geneva, Switzerland

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 24, 2022

Primary Completion (Actual)

February 1, 2026

Study Completion (Actual)

April 1, 2026

Study Registration Dates

First Submitted

October 4, 2022

First Submitted That Met QC Criteria

October 4, 2022

First Posted (Actual)

October 6, 2022

Study Record Updates

Last Update Posted (Actual)

May 4, 2026

Last Update Submitted That Met QC Criteria

April 28, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2022-D0058

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Published and analyzed data will be archived in a secure location on a data sharing server that meets the FAIR (Findability, Accessibility, Interoperability, and Reuse) principles for a minimum of 10 years.

IPD Sharing Time Frame

Once the study has been published

IPD Sharing Access Criteria

Open Access

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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