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Enhancing Phonological Decoding in Post-Stroke Aphasia: A Pilot Study of Combined tDCS and Phono-Motor Treatment
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Olga Boukrina1,2, Priyanka Shah-Basak3, Samantha Dasilva1, Shelley Laitinen3, Ann Kukowski3, Sidney Schoenrock3, Elizabeth B. Madden4; 1Kessler Foundation, West Orange, NJ, USA, 2Rutgers New Jersey Medical School, Newark, NJ, USA, 3Medical College of Wisconsin, Milwaukee, WI, USA, 4Florida State University, Tallahassee, FL, USA
Reading deficits affect majority of individuals with post-stroke aphasia (Brookshire et al., 2014), limiting independence and quality of life. Phono-Motor Treatment (PMT)(Kendall & Nadeau, 2016) is an evidence-based aphasia intervention shown to improve reading (Boukrina et al., 2024; Madden et al., 2021). However, it requires intensive, multi-week delivery and may not fully address underlying neural dysfunction, such as inadequate perfusion of perilesional brain areas (Ivanova et al., 2024; Walenski et al., 2022). Transcranial direct current stimulation (tDCS) modulates cortical excitability and cerebral perfusion and has shown promise for enhancing language recovery when paired with behavioral therapy (Shah-Basak et al., 2023). This pilot study evaluated the feasibility of combining PMT with tDCS and examined differences in outcomes across stimulation timing conditions (early, late, alternating). We hypothesized that tDCS would enhance PMT efficacy by accelerating gains in reading and phonological processing, with greater improvement during active relative to sham stimulation periods. Six individuals with chronic post-stroke aphasia (2 women, age=61.67±9.27, WAB AQ=83.37±20.45) participated in a randomized, sham-controlled, double-blind study. All participants received 6 weeks of PMT (2 hours/day, 5 days/week). They were assigned to one of three conditions (n=2/group): 3 weeks active tDCS + 3 weeks sham (early), 3 weeks sham + 3 weeks active tDCS (late), or 6 weeks alternating active/sham stimulation. tDCS (2 mA, 20 min; anode CP5 (left posterior parietal cortex), cathode Fp2) was applied within ±5 minutes of PMT onset. Sham used 30-second ramp-up/down to mimic stimulation sensation. Behavioral assessments at baseline, mid-, and post-treatment included reading aloud (words, nonwords), Western Aphasia Battery (WAB)(Kertesz, 2007), Reading Comprehension Battery for Aphasia (RCBA)(La Pointe & Horner, 1998), and nonverbal measures of semantic (picture and word matching), orthographic (foil vs. accurate spelling), and phonological processing (pseudoword rhyme judgement). Changes were assessed using Wilcoxon signed-rank tests. Nonword reading accuracy improved significantly (W=21, p=.031, r=.90), with all participants showing positive change. Word reading did not significantly change (W=1, p>.063, r=.73), consistent with ceiling effects (Fig. 1). Improvements were greater during active than sham stimulation in all participants who received early/late blocked conditions (n=4), although not statistically significant (p=.125). Participants receiving alternating stimulation also improved, with comparable changes relative to the blocked conditions. Pseudoword rhyme judgement accuracy trended towards improvement (baseline: 70%±14.9; outcome: 80%±12.9), with 5/6 participants improving (W=15, p=.063, r=.90). This suggests gains extended to phonological processing, consistent with PMT focus, and were potentially enhanced by tDCS. No significant changes were observed in WAB, RCBA, or in semantic and orthographic processing, consistent with relatively mild aphasia and ceiling effects on those tests. These findings support combining PMT with tDCS for post-stroke reading deficits. Selective improvements in nonword reading and trends in phonological processing suggest enhanced sublexical decoding, with possible modulation by tDCS. Given evidence that PMT generalizes across language domains (Silkes et al., 2019), future studies should incorporate functional reading outcomes to assess real-world impact and whether combined tDCS+PMT gains exceed those achieved with PMT alone. If confirmed in larger samples, this approach could help reduce therapy duration and facilitate clinical translation.
Topic Areas: Disorders: Acquired, Reading