Transcranial Direct-Current Stimulation in Subacute Aphasia: A Randomized Controlled Trial

Abstract

Background: Transcranial direct-current stimulation (tDCS) is a promising adjunct to therapy for chronic aphasia.

Methods: This single-center, randomized, double-blind, sham-controlled efficacy trial tested the hypothesis that anodal tDCS augments language therapy in subacute aphasia. Secondarily, we compared the effect of tDCS on discourse measures and quality of life and compared the effects on naming to previous findings in chronic stroke. Right-handed English speakers with aphasia <3 months after left hemisphere ischemic stroke were included, unless they had prior neurological or psychiatric disease or injury or were taking certain medications (34 excluded; final sample, 58). Participants were randomized 1:1, controlling for age, aphasia type, and severity, to receive 20 minutes of tDCS (1 mA) or sham-tDCS in addition to fifteen 45-minute sessions of naming treatment (plus standard care). The primary outcome variable was change in naming accuracy of untrained pictures pretreatment to 1-week posttreatment.

Results: Baseline characteristics were similar between the tDCS (N=30) and sham (N=28) groups: patients were 65 years old, 53% male, and 2 months from stroke onset on average. In intent-to-treat analysis, the adjusted mean change from baseline to 1-week posttreatment in picture naming was 22.3 (95% CI, 13.5-31.2) for tDCS and 18.5 (9.6-27.4) for sham and was not significantly different. Content and efficiency of picture description improved more with tDCS than sham. Groups did not differ in quality of life improvement. No patients were withdrawn due to adverse events.

Conclusions: tDCS did not improve recovery of picture naming but did improve recovery of discourse. Discourse skills are critical to participation. Future research should examine tDCS in a larger sample with richer functional outcomes.

Registration: URL: https://www.

Clinicaltrials: gov; Unique identifier: NCT02674490.

Keywords: aphasia; electrical stimulation; ischemic stroke; language; quality of life.

Fig. 1.

CONSORT Subject Flow diagram The primary analysis completers sample included of all of those for whom the primary outcome measure was collected (PNT one week after treatment). The modified Intent to Treat sample included all of those who participated in at least one treatment session. † Patient 1 was withdrawn because aphasia was too severe. Patient 2 was withdrawn prior to starting therapy because patient recovered. ‡ Patient was withdrawn to be admitted to subacute rehab facility. Early terminations in the sham tDCS group were as follows: 1) patient had a right middle cerebral artery stroke after 11 treatment sessions; 2) patient was not able to understand the treatment task, which was discontinued after a single session; 3) patient declined remote follow-up sessions offered at the start of the Covid-19 pandemic.

Fig. 2.

Comparison of results from subacute vs chronic stroke Two outliers were removed from the figure: 1 chronic participant who received A-tDCS experienced profoundly decreased performance of 129.5/175 and 1 participant in the present study who received sham tDCS experienced profoundly increased performance of 108.5 items.