The purpose of this study is to determine if non-invasive electrical brain stimulation can enhance the outcome of intensive language therapy in chronic aphasia.

Stroke is the leading cause of death and disability worldwide. Given the increasing average lifespan worldwide, the incidence and prevalence of patients with stroke will dramatically increase in the future. One of the most frequent and devastating conditions after stroke is aphasia, which affects language production and comprehension. High-frequent intensive speech-and-language therapy is currently the treatment of choice in chronic aphasia. However, despite its general effectiveness, treatment effect sizes are only low to moderate. Thus, there is a pressing need to explore novel training-adjuvant therapies to enhance treatment efficacy. Moreover, very little is known about the neurobiology of treatment-induced recovery in chronic aphasia. This is the prerequisite to improve existing and/or develop new treatment paradigms.

Thus, in the present project the investigators aim to assess whether the outcome of intensive language training can be enhanced by adjuvant non-invasive brain stimulation. They will be using anodal transcranial direct current stimulation (atDCS) that has previously been shown to enhance (a) language and motor learning in healthy subjects and (b) motor recovery in stroke patients. Specifically, in a longitudinal group comparison design, two matched groups of patients with chronic anomia will receive two weeks of intensive language training with or without atDCS. Treatment effects will be assessed immediately after the two week intervention period and several months after the end of the training. The Investigators will also use functional and structural magnetic resonance imaging (MRI) to elucidate language network changes in the two groups.

Inclusion Criteria:

• chronic stroke (> 1 year after event)
• aphasia due to stroke with naming impairment
• German as first language
• first-ever stroke

Exclusion Criteria:

• more than 1 stroke
• history of severe alcohol or drug abuse, psychiatric illnesses like severe depression, poor motivational capacity
• dementia
• contraindications for Magnetic Resonance Imaging or transcranial direct current stimulation