Up to 40% of stroke survivors suffer from aphasia, making recovery of language abilities a top priority in stroke rehabilitation. Conventional speech and language therapy may have limited effectiveness. Leveraging multimodal data (behavioral, neuroimaging, and genetics), this study aims to 1) evaluate the efficacy of combining tDCS with speech therapy, 2) examine neural changes associated with recovery, 3) identify factors influencing response to treatment.

Approximately one million people in the United States are living with aphasia, an acquired neurological disorder affecting the ability to use and/or understand language. This communication impairment affects up to 40% of stroke patients. Stroke victims usually prioritize speaking, writing, and walking as the three most important rehabilitation goals, two of these goals therefore involving communication. Conventional speech therapy strategies have nevertheless limited effectiveness in post-stroke aphasia. Indeed, approximately half of those affected will remain in this state despite intensive speech therapy. Effective novel treatment is therefore warranted to improve recovery in these patients. Recent evidence suggests that transcranial direct current stimulation (tDCS), a non-invasive, low-cost neuromodulation technique, applied in conjunction with speech therapy may be more effective in promoting language recovery than behavioral intervention alone.

A double-blind quasi-randomized controlled study will be carried out in chronic post-stroke aphasics. Participants will be assigned to either the tDCS group or to the sham (placebo) group and will receive 20 minutes of concurrent speech and language therapy by a trained speech therapist over five consecutive days. Behavioral, EEG, and MRI data will be acquired within one week before and after intervention. Genetic samples will be collected once. Secondary behavioral outcome measures will be performed again 3 months following tDCS/sham intervention to assess long-term benefits.

Inclusion Criteria:

• Between ages 18-85
• At least 12 months post stroke
• Diagnosed with aphasia due to ischemic or hemorrhagic stroke
• English speaking
• Right handed prior to stroke

Exclusion Criteria:

• Nonverbal
• Other neurological diseases/disorders
• Not MRI-compatible (e.g. claustrophobia, metal implants in the head)

The only person knowing about this assignment will be the Principal Investigator.