The Effects of Transcranial Direct-Current Stimulation on Cognition in Stroke Patients

Background And Purpose: To investigate whether transcranial direct-current stimulation (tDCS) can improve cognition in stroke patients.

Methods: Forty-five stroke patients (20 males and 25 females, average age: 62.7 years) with cognitive dysfunction were included in this prospective, double-blinded, randomized case-control study. All patients were right-handed and the mean elapsed time after stroke was 39.3 days. Three different treatments groups were used: (1) anodal stimulation of the left anterior temporal lobe, (2) anodal stimulation of the right anterior temporal lobe, and (3) sham stimulation. tDCS was delivered for 30 minutes at 2 mA with 25 cm(2) electrodes, five times/week, for a total of 3 weeks, using a Phoresor II Auto Model PM 850 (IOMED(®)). The evaluation of cognitive impairment was based on a Computerized Neuropsychological Test (CNT), Korean Mini-Mental State Examination (K-MMSE). The Korean version of the Modified Barthel Index (K-MBI) was used to assess activities of daily living functionality. These evaluations were conducted in all patients before and after treatment.

Results: Each group included 15 patients. Pre-treatment evaluation showed no significant differences between the three groups for any of the parameters. There was significant improvement in the verbal learning test on the CNT in the left anodal stimulation group (P < 0.05). There were, however, no significant differences in the K-MMSE or K-MBI scores among the three groups.

Conclusions: These results demonstrated the beneficial effects of anodal tDCS on memory function. Thus, tDCS can successfully be used as a treatment modality for patients with cognitive dysfunction after stroke.