Transcranial direct current stimulation improves naming in aphasic patients

Technique for focal modulation of brain that induces persisting excitability changes of human cerebral cortex. This brain stimulation technique can be also adjuvant strategy to improve functional recovery after ischemic stroke. Nonetheless, although the ability to generate lists of words increases after tDCS in normal subjects, the effects of tDCS in patients with aphasia are unknown. This study aimed to assess the effect of tDCS over left fronto-temporal areas in chronic non-fluent post-stroke aphasia. Methods: Eight patients with chronic non-fluent aphasia were studied before and immediately after tDCS (2mA, 10 minutes) over the damaged left fronto-temporal areas. The naming function was measured by a computercontrolled task. To assess the specificity of our findings, in additional control experiments patients were evaluated before and after cathodal tDCS over the occipital cortex. Results:Whereas anodal tDCS and sham tDCS over the left fronto-temporal areas failed to induce significant changes ([mean ± SE] anodal tDCS, pre 12.0±2.29 vs post 11.83±2.29, p=0.20; sham tDCS, pre 11.70±2.14 vs post 11.70±2.15, p=0.20), cathodal tDCS significantly increased the accuracy of the naming task (cathodal tDCS,pre 11.70±1.96 vs post 14.50±1.69, p=0.002). Cathodal tDCS over occipital cortex did not induce any effect on naming function. Conclusions: Cathodal tDCS over the damaged left fronto-temporal areas in patients with chronic non-fluent aphasia improves naming. Because tDCS is simple, safe and inexpensive, this technique could be complementary to speech rehabilitation in the management of aphasic patients.