Transcranial Direct Current Stimulation to Enhance Training Effectiveness in Chronic Post-Stroke Aphasia

Inclusion Criteria:

• left-hemisphere cortical or subcortical stroke with first-ever aphasic symptoms

• at least 6 months post-onset of stroke;

• aphasia, as determined by the Aachen Aphasia Test (AAT);

• 13 moderate-to-severe word finding difficulties (maximum of 75% correct items on acomputerized naming task at baseline);

• at least 1 correct reaction on the first part of the AAT subscale Token Test (ensuring basic comprehension skills);

• at least 1 point on the communicative task of the AAT subscale Spontaneous Speech (ensuring basic communication abilities);

• German as first language;

• intact left-hemisphere "hand knob" without right prefrontal lesions for placement oftDCS electrodes, as confirmed by magnetic resonance imaging or computer tomographyscans.

Exclusion Criteria:

• contraindications for tDCS (e.g., cardiac pacemaker, history of seizures, implantedmetal inside the head);

• more than one clinically apparent stroke with aphasic symptoms;

• other severe neurological diseases (e.g., brain tumor, and subdural hematoma);

• epilepsy with seizures during the last 12 months prior to study start and/or intakeof sedating antiepileptic drugs (barbiturates and benzodiazepines),

• history of severe alcohol or drug abuse;

• current severe depression;

• current psychosis or other relevant psychiatric condition;

• very severe apraxia of speech, as revealed by Hierarchical Word Lists;

• severe non-verbal cognitive deficits, as indicated by the Corsi Block-Tapping Task;

• severe uncontrolled medical problems;

• severely impaired vision or hearing that prevents patients from engaging inintensive SLT;

• changes in centrally active drugs within 2 weeks prior to study inclusion.