Prismatic adaptation coupled with cognitive training as novel treatment for developmental dyslexia: a randomized controlled trial

Despite intense and costly treatments, developmental dyslexia (DD) often persists into adulthood. Several brain skills unrelated to speech sound processing (i.e., phonology), including the spatial distribution of visual attention, are abnormal in DD and may represent possible treatment targets. This study explores the efficacy in DD of rightward prismatic adaptation (rPA), a visuomotor adaptation technique that enables visuo-attentive recalibration through shifts in the visual field induced by prismatic goggles. A digital intervention of rPA plus cognitive training was delivered weekly over 10 weeks to adolescents with DD (aged 13-17) assigned either to treatment (N = 35) or waitlist (N = 35) group. Efficacy was evaluated by repeated measures MANOVA assessing changes in working memory index (WMI), processing speed index (PSI), text reading speed, and words/pseudowords reading accuracy. rPA treatment was significantly more effective than waitlist (p ≤ 0.001; ηp2 = 0.815). WMI, PSI, and reading speed increased in the intervention group only (p ≤ 0.001, ηp2 = 0.67; p ≤ 0.001, ηp2 = 0.58; p ≤ 0.001, ηp2 = 0.29, respectively). Although modest change was detected for words and pseudowords accuracy in the waitlist group only (words: p ≤ 0.001, d = 0.17, pseudowords: p = 0.028; d = 0.27), between-group differences were non-significant. rPA-coupled cognitive training enhances cognitive and reading abilities in adolescents with DD. This innovative approach could have implications for early remedial treatment.