A team of rehabilitation specialists, neurologists, and aphasia researchers led by faculty from Johns Hopkins University have published results of a study on the effects of transcranial direct current stimulation (tDCS) on everyday functional communication in chronic aphasia. The goals of the study were to investigate the therapeutic effects of tDCS, when administered in conjunction with a naming-oriented treatment intervention delivered by computer.
Twenty-eight persons with chronic aphasia were enrolled in a randomized, double-blind, controlled study. Subjects ranged in age from 34-89 y/o, in time post-onset from 6 months to 14 years, and in aphasia severity on the Boston Diagnostic Aphasia Examination’s rating scale from 1 (very severe) to 4 (mild). Each subject participated in 45 sessions of object-naming activity on a computer, of which 15 sessions were preceded by anodal-, 15 by cathodal-, and 15 by sham-cerebellar tDCS, with half the participants randomly assigned to anodal stimulation before cathodal, and the other half – cathodal before anodal. During sessions, subjects were shown the picture of an object, after which a video of a speaker’s face appeared on screen saying a word that either matched or did not match that object, along with two large on-screen buttons by which subjects registered whether the word matched the picture, or not. Feedback was immediate, the computer showing a smiley face for correct or a frowny face for incorrect. Treatment effects were assessed using the two dimensions of the American Speech-Language-Hearing Association’s Functional Assessment of Communication Skills in Adults (ASHA FACS) — the Communication Independence (CI) scale, and the Qualitative Dimension of Communication (QDC) scale. Linear, mixed-effects regression models were used to analyze data for effects of intervention on ASHA FACS communication dimensions, and to investigate relationships between functional communication skills and trained or untrained naming abilities.
Analyses shows that tDCS induced statistically significant improvement in subjects’ overall mean QDC score (Qualitative Dimension of Communication), but not in their overall mean score for Communication Independence. The QDC beneficial effect were found immediately post-treatment, at two weeks post-treatment, and at two months post-treatment; effects of cathodal stimulation were not significantly different from the effects of anodal stimulation. In contrast to QDC scores, overall CI mean scores did not change significantly at any point. Still, in the tDCS conditions, the researchers did show a linear association between changes in CI scores and changes in naming scores.
For further reading: J. H. Kim, S. Cust, B. Lammers et al., (14 Mar 2024),
Cerebellar tDCS enhances functional communication skills in chronic aphasia. Aphasiology. DOI: https://doi.org/10.1080/02687038.2024.2328874