Transcranial direct current stimulation (tDCS) of Broca's area in chronic aphasia: A controlled outcome study

Background: In the last decade transcranial direct current stimulation (tDCS) has been introduced in aphasia post-stroke recovery as a tool for modulating neuroplasticity. However, it is still unclear whether tDCS should be applied at rest (off-line) or combined with behavioral treatment strategies (on-line), therefore, this study investigates the effect of repeated sessions of off-line tDCS on language recovery in post-stroke chronic aphasic patients. Methodology: Eight post-stroke patients with different type and degree of chronic aphasia underwent two weeks of off-line anodal tDCS (2 mA intensity for 20 min a day) on Broca's area and two weeks of sham stimulation as a control condition. Language recovery was measured assessing object and action naming abilities with a computerized picture naming task. Results: No significant difference between anodal tDCS and sham stimulation, both for object and action naming tasks, was found. Descriptive analysis of single cases showed that after tDCS only one patient improved substantially on action naming task. Conclusion: With the exception of one patient, the overall results suggest that in chronic aphasic patients the off-line tDCS protocol applied in this study is not effective in improving noun and verb naming abilities.