Poster E19, Thursday, August 22, 2019, 3:45 – 5:30 pm, Restaurant Hall
Transcranial direct current stimulation as an adjuvant to aphasia treatment may provide greater benefit to individuals with longer-term chronic aphasia
Lorelei Phillip Johnson1, Alexandra Basilakos1, Leonardo Bonilha2, Chris Rorden1, Julius Fridriksson1;1University of South Carolina, 2Medical University of South Carolina
Over 2 million people in North America are living with aphasia (Simmons-Mackie, 2018). Recent studies indicate that long-term recovery in aphasia is possible (Holland et al., 2017; Johnson et al., 2018) even in individuals who have been living with aphasia for at least 5 years. However, very little is known about the nature of aphasia recovery occurring many years after a stroke has taken place. The goal of the current study was to examine differences in treated recovery for individuals five years or longer post-stroke (described here as ‘long-term’ chronic aphasia) as compared to those who are earlier in the recovery process (i.e. <5 years or ‘shorter-term’ chronic aphasia). The data included here were collected as a part of a previously published phase II randomized controlled futility trial for anodal transcranial direct current stimulation (A-tDCS) as an adjuvant to aphasia treatment (Fridriksson et al., 2018). The results of the trial suggested that further study of tDCS in aphasia is not futile, and a follow-up analysis indicated that those who received A-tDCS showed significantly greater improvement on both treated and untreated stimuli compared to individuals who received sham tDCS (S-tDCS; Fridriksson et al., 2019). In a retrospective analysis, participants were grouped by time post-stroke. Of the 74 individuals in the original clinical trial, 73 (21 female, mean age=59.3) were included in the analyses detailed here. There were 21 individuals with long-term aphasia (9 received A-tDCS), and 52 individuals with shorter-term aphasia (24 received A-tDCS). For each participant, the amount of proportional change from baseline to 1-week post-treatment was calculated for performance on the Philadelphia Naming Test (untreated items) and a subset of treated items (“Naming 80”). An ANCOVA was conducted to determine main effects of group (shorter-term vs long-term) and stimulation type (active vs sham) while controlling for differences in baseline severity as quantified by the quotient score (AQ) on the Western Aphasia Battery-Revised (WAB-R). Because of the relatively small group size and exploratory nature of the analysis, the p-value was set at .10. For the treated items, there were significant effects of WAB AQ (p<.001, partial eta2=.296), stimulation type (p=.011, partial eta2=.092), and the group by stimulation type interaction (p=.078, partial eta2=.045). The interaction revealed that the difference in proportional change for those receiving active versus sham treatment was larger in the long-term chronic aphasia group. For the untreated items, there was only a significant effect of WAB AQ (p=.021, partial eta2=.076) though the effect of stimulation type approached significance (p=.144, partial eta2=.031). An expected effect of stimulation was shown for naming of treated items. Though this same effect was not shown for untreated items, it is possible that with a larger sample of individuals with long-term aphasia, these differences may become clearer. Though only a first step in understanding long-term treated recovery in aphasia, these data are promising and warrant further investigation to understand how treatment response and underlying neural mechanisms may evolve years and even decades post-stroke.
Themes: Disorders: Acquired, Language Therapy
Method: Neurostimulation