Combining transcranial direct current stimulation with a rhythm-based intervention to improve reading fluency in young adults with dyslexia

Recent evidence suggests that reading performance can be enhanced through non-invasive brain stimulation, which modulates excitability in brain regions involved in reading. However, no studies have tested a multi-session protocol combining tDCS with reading training in adults with developmental dyslexia. The present study investigated the efficacy of combining transcranial direct current stimulation (tDCS) with a behavioral intervention – Rhythmic Reading Training (RRT) – to improve reading skills in university students with dyslexia. Twenty participants (aged 19–26) diagnosed with dyslexia completed a 10-day intervention comprising daily 30-minute sessions of RRT and 15 min of concurrent online tDCS. A constant current of 1.5 mA was applied for 20 min in a bipolar montage with the anode over the left temporoparietal junction (TPJ) and the cathode over the right TPJ. Participants were randomly assigned to either an active or sham tDCS condition, matched for sociodemographic characteristics, intellectual functioning, and severity of reading difficulties. Reading performance, verbal working memory, rapid automatized naming (RAN), and rhythm perception were assessed at baseline (pre-training), immediately after the intervention (post-training), and at a 4-week follow-up. Results showed that the behavioral intervention alone was sufficient to engage phonological processing, as evidenced by significant improvements in nonword reading speed in both the active and sham groups. Additionally, tDCS produced sustained gains in the most ecologically valid measure of reading, namely, text reading speed. These findings indicate that a short, intensive RRT program effectively improves reading speed in university students with dyslexia and that combining RRT with active tDCS over the left temporoparietal cortex may enhance the durability of text reading speed gains through brain plasticity mechanisms.