Brain Stimulation With Combined Reading and Motor Training for Children With Dyslexia

This is a randomized, double-blind, sham-controlled, 8-group component trial in 9-year-old boys with developmental dyslexia. The study tests a theory-driven prediction derived from multiple-deficit models of dyslexia: that simultaneously targeting reading-related and sensory-motor brain networks, while delivering an integrated phonological and fine motor intervention, produces greater and more durable reading improvement than single-component interventions.

The tDCS protocol uses 1 mA current for 20 minutes per session over 20 sessions (3 sessions/week). Electrode montages are yoked to the type of cognitive intervention: left temporoparietal (TPJ) for phonological training, left primary motor cortex (M1) for motor training, and dual-site TPJ+M1 for the combined intervention. A tDCS-only group (M1 montage) is included to isolate the effect of motor cortex stimulation.

Primary outcome: change in the composite score of Factor 1 of the Reading and Dyslexia Test (word reading, phoneme deletion, nonword reading, and word comprehension). Secondary outcomes: fine motor performance (BOT-2), rapid automatized naming, and text reading fluency.

Assessments occur at baseline, immediately after the intervention, and at 3- and 6-month follow-ups.

Inclusion criteria

• Male children aged 9 years (9 years 0 months to 9 years 11 months) with developmental dyslexia diagnosed according to DSM-5 criteria by a clinical team.
• Reading and Dyslexia Test (NAMA) T score ≤ 30 (at least 2 standard deviations below the mean).
• Full Scale IQ ≥ 85 on the Wechsler Intelligence Scale for Children, Fifth Edition (WISC-V).
• Score below 88 on the Spence Children's Anxiety Scale (SCAS).
• Fine motor deficits defined as standard score ≤ 40 on Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOT-2) manual dexterity and upper-limb coordination subtests.
• Normal or corrected-to-normal vision and hearing.
• No history of seizure or epilepsy, no scalp skin disease, no cochlear implant, cardiac pacemaker, or metal implants in the skull.
• Written informed consent from parents or legal guardian and verbal assent from the child.

Exclusion criteria

• Intellectual disability (Full Scale IQ < 85).
• Personal history of epilepsy or seizure disorder, or epilepsy in a first-degree relative.
• Presence of cochlear implant, cardiac pacemaker, or metal implants in the skull.
• Skin diseases or open lesions on the scalp at electrode sites.
• Uncorrected visual or hearing impairments.
• Other primary psychiatric or neurodevelopmental disorders requiring ongoing treatment (e.g., ADHD, autism spectrum disorder, severe anxiety disorder).