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Poster A48, Thursday, August 16, 10:15 am – 12:00 pm, Room 2000AB

Left-lateralizing tDCS for aphasia: a randomized, double-blind, placebo-controlled clinical trial

Elizabeth H Lacey1,2, Fama Mackenzie E1, Anbari Zainab1, Turkeltaub Peter E1,2;1Department of Neurology, Georgetown University, 2MedStar National Rehabilitation Hospital

Introduction: Roughly 20% of stroke survivors are left with chronic aphasia after the period of spontaneous recovery has stopped or slowed. Although speech-language therapy is effective and can continue to improve recovery in the chronic phase (Brady et al., 2012), the last ten years have seen increasing interest in the use of non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) to enhance the effect of behavioral treatment (Fama & Turkeltaub, 2014). The current study, a randomized, placebo-controlled, double-blind clinical trial, was designed to determine whether a brief course of tDCS intended to enhance left frontal lateralization can improve naming when added to speech therapy in people with chronic aphasia due to left hemisphere stroke. Methods: Participants with left hemisphere strokes and no other neurological issues completed an evaluation of language and cognition tests before treatment. They were randomized 1:2 to a sham condition or 1.5 mA HD-tDCS with anodes over electrode sites F5 and F7 and cathodes over F6 and F8. Stimulation was administered 20 minutes a day for 5 days at the beginning of a one-hour multi-modal speech therapy session. The primary outcome measure was the Western Aphasia Battery Naming and Word-finding score. Secondary outcome measures included oral and written naming of pictures on the Philadelphia Naming Test. The primary and secondary outcome measures were assessed 24 hours after the last day of treatment, and again 3 weeks and 12 weeks later. Effects of tDCS were tested using a repeated-measures ANOVA for effects of arm (tDCS, sham) vs. time (pre, post, 2-week, 3-month). Results: Thirty-nine participants were randomized, 38 were treated, and 37 completed all follow-ups. HD-tDCS was well tolerated; there were no adverse events reported, or attrition due to discomfort from the treatment. The effect of tDCS was not significant for the primary outcome measure, but people in the active condition tended to show greater improvement (F(3,105) = 1.78, P = .16, partial-eta-squared=.048, small-medium effect-size). Among the secondary outcome measures, a significant effect of tDCS was observed only for written naming (F(3,96) = 4.68, P = .004, partial eta-squared = .128). Conclusion: We report a negative trial for five consecutive sessions of 1.5 mA HD-tDCS to the bilateral inferior frontal gyri, aimed at increasing left lateralization. Although the trial was negative, the data indicated a weak positive effect of tDCS on the primary outcome measure, and a larger effect on written naming (exploratory). The positive effect sizes observed after a short course of stimulation suggest that further research is needed to optimize tDCS treatment for chronic aphasia. Optimization may require addressing individual differences in responsiveness to stimulation, the choice of electrode locations, the dose in intensity, duration, and number of stimulation sessions, timing of stimulation relative to behavioral treatment, and the behavioral target of treatment. References: Brady MC, Kelly H, Godwin J, Enderby P. Speech and language therapy for aphasia following stroke. Cochrane Database Syst Rev. 2012;5:CD000425. Fama ME, Turkeltaub PE. Treatment of Poststroke Aphasia: Current Practice and New Directions. Semin Neurol. 2014;34:504-513

Topic Area: Language Therapy