Transcranial Direct Current Stimulation vs Sham Stimulation to Treat Aphasia After Stroke

Abstract

IMPORTANCE Aphasia is a debilitating language disorder for which behavioral speech therapy is the most efficient treatment, but therapy outcomes are variable and full recovery is not always achieved. It remains unclear if adjunctive brain stimulation (anodal transcranial direct current stimulation [A-tDCS]) applied during aphasia therapy can improve outcomes. OBJECTIVE To examine the futility of studying A-tDCS as an adjunctive intervention during speech therapy to improve speech production (naming) for individuals with long-term poststroke aphasia. DESIGN, SETTING, AND PARTICIPANTS Double-blinded, prospective randomized clinical trial using a futility design to test adjunctive A-tDCS during speech therapy. The setting was an outpatient clinic. Enrollment of individuals began in August 2012 and was completed in March 2017, and the duration of follow-up was 6 months. Analyses began in April 2017. The study recruited from a volunteer sample, and 89 patients were screened. Patients with long-term (>6 months) aphasia due to 1 previous left hemisphere stroke were enrolled. In comparing A-tDCS and sham tDCS, patients were matched based on site (University of South Carolina or Medical University of South Carolina), baseline age, type of aphasia, and aphasia severity. INTERVENTIONS Outpatient speech therapy for 3 weeks (15 sessions, 45 minutes each) combined with either A-tDCS vs sham tDCS applied to preserved left temporal lobe regions. MAIN OUTCOMES AND MEASURES The primary outcome was the ability to name common objects, assessed twice before and after therapy. RESULTS A total of 74 patients were enrolled. Participants had a mean (SD) age of 60 (10) years, had 15 (2) years of education, and were 44 (40) months from stroke onset. There were 52 men (70%) and 62 non-Hispanic white individuals (84%). Most were retired or not employed (59 [80%]). Broca aphasia was the most common aphasia type (39 [52.7%]). The adjusted mean (SE) change from pretreatment baseline in correct naming was 13.9 (2.4) words (95% CI, 9.0-18.7) for A-tDCS and 8.2 (2.2) words (95% CI, 3.8-12.6) for sham tDCS, with mean (SE) A-tDCS difference of 5.7 (3.3) words (95% CI, −0.9 to 12.3), indicating a relative 70% increase in correct naming for A-tDCS relative to sham. The futility hypothesis P value was .90, indicating failure to reject the null hypothesis and, therefore, providing no evidence that further study of A-tDCS is futile. No serious adverse events were associated with A-tDCS. CONCLUSIONS AND RELEVANCE Our findings provide motivation to proceed with another trial to study the effect of A-tDCS on the outcome of aphasia treatment in individuals poststroke. Anodal tDCS during speech therapy is feasible and potentially transformative for aphasia treatment and should be further studied.

Neuroplasticity and aphasia treatments: new approaches for an old problem

“…Although NIBS studies in aphasia generally have been small with variable findings, one recent large randomised, sham-controlled clinical trial indicates that active tDCS supplements the effects of aphasia treatment compared with sham. 33 Neural activity evoked by linguistic and non-linguistic behavioural strategies also may have the potential to evoke long-term relearning and brain-system reorganisation during aphasia treatment.…”

“…An alternative approach involves mapping of the residual language network using functional imaging s19, s20 to identify stimulation sites vital to recovery. 33 s8, s26 This approach can induce substantial gains in language performance over that of treatment alone as demonstrated in a large randomised clinical trial (RCT, N=74) 33 ; however, it is cost-intensive and requires substantial technological expertise. Other approaches exploit known effects of NIBS on functionally connected regions.…”

BDNF genotype and tDCS interaction in aphasia treatment

“…Most of the early studies on A-tDCS and aphasia included only a small number of participants [ 5 , 6 , 8 – 12 ]. This was the motivation for the much larger and more definitive double-blinded RCT comparing the outcome of three weeks of aphasia treatment (5 days/week) in a group of chronic post-stroke participants with aphasia who were randomized to receive A-tDCS (N = 34) or S-tDCS (N = 40) [ 13 ]. This study utilized a futility design: the null hypothesis stated that A-tDCS results in better aphasia treatment outcome than S-tDCS, whereas the alternative hypothesis stated that there is no evidence that A-tDCS is superior to S-tDCS.…”

Robotic Arm Rehabilitation in Chronic Stroke Patients With Aphasia May Promote Speech and Language Recovery (but Effect Is Not Enhanced by Supplementary tDCS)

“…While we must be cautious about drawing strong conclusions from this dataset, it is possible that this reflects the fact that there was no explicit speech/language activity paired with the stimulation and that any benefit tDCS may provide in stroke rehabilitation comes from pairing of treatment and stimulation. We also note that recent findings on whether tDCS can affect language processing have been mixed, with recent positive findings reported for tDCS as an adjunct to aphasia therapy ( 9 ) and stuttering therapy ( 10 ) but null findings also widely reported ( 11 ).…”