Impact of phonological awareness intervention combined with transcranial direct current stimulation on rapid automatized naming and verbal short term memory in developmental dyslexia: a randomized controlled trial

This study evaluates the effects of phonological awareness (PA) and combined PA/transcranial direct current stimulation (tDCS) interventions to improve rapid automatized naming (RAN) and verbal short-term memory (VSTM) in developmental dyslexia. In this randomized, double-blind, sham-controlled clinical trial, we included a PA+sham tDCS group [Mean age: 9.54 (1.15), 71% male] and a PA+ active tDCS group [Mean age: 9.18 (1.30), 85% male] in which we applied tDCS over the left parieto-temporal junction. Each volunteer participated in 15 intervention sessions (session duration 60 min, 3 times per week × 5 weeks). Data of the groups over time were analyzed by a mixed model analysis of variance (ANOVA) with the between-subject factor group and the within-subject factor time. The PA intervention led to increased RAN and VSTM test scores in both groups after the end of interventions (p < 0.05). tDCS had no further effect on outcome measures as compared to PA intervention alone. PA training is valuable to improve RAN and VSTM abilities in dyslexia. Anodal tDCS during the PA intervention had no further therapeutic effect on these skills. Therefore, the use of anodal tDCS over the left parieto-temporal junction is not recommended to improve RAN and VSTM functions in dyslexia.