Transcranial direct current stimulation (tDCS) has been found to improve naming ability in patients with post-stroke aphasia when coupled with therapeutic language rehabilitation. Previous studies have used functional imaging of nonviable cortical regions of the residual language function network and targeted specific domains for this stimulation. This study evaluated the effects of primary motor cortex, M1, stimulation on naming ability, among stroke patients, assessed immediately after and six months following stimulation.

This randomized, double-blind, clinical trial included 26 subjects with a post-stroke duration of over 12 months, with chronic aphasia and impaired naming ability. The subjects were matched by naming impairment severity. All underwent treatment with a language computer-assisted program, and were randomized to receive either anodal tDCS or sham tDCS. The primary outcome variable was the mean change in naming ability.

Naming ability for the trained items was significantly improved in both groups immediately and at six months′ follow-up, with the effect trending larger for the tDCS group (P＝0.08). The maintenance of effect at six months was greater for the tDCS group than the sham group (P＝0.01). Generalization of treatment effects to untrained items were found in both groups immediately after Number 5the training but this effect was significantly larger in the tDCS group (P＝0.0009).

This study of patients with chronic stroke found that transcranial direct current stimulation, directed at M1, can augment language therapy outcomes, with intervention maintenance effects noted at six months.