A Double-Blind, Sham-Controlled, Pilot Study to Assess the Effects of the Concomitant Use of Transcranial Direct Current Stimulation with the Computer Assisted Cognitive Rehabilitation to the Prefrontal Cortex on Cognitive Functions in Patients with Strok

OBJECTIVE: To examine the synergistic effects of both computer-assisted cognitive rehabilitation (CACR) and transcranial direct current stimulation (tDCS) on cognitive function in patients with stroke. METHODS: The current double-blind, sham-controlled study enrolled a total of 11 patients who were newly diagnosed with stroke. The patients of the tDCS group (n=6) completed sessions of the Korean computer-assisted cognitive rehabilitation program five times a week for 30 minutes a session during a mean period of 18.5 days concomitantly with the anodal tDCS over the bilateral prefrontal cortex combined with the CACR. The patients of the control group (n=5) also completed sessions of the sham stimulation during a mean period of 17.8 days. Anodal tDCS over bilateral prefrontal cortex (F3 and F4 in 10-20 EEG system) was delivered for 30 minutes at an intensity of 2 mA. Cathode electrodes were applied to the non-dominant arm. All the patients were evaluated using the Seoul Computerized Neuropsychological Test (SCNT) and the Korean Mini-Mental State Examination. RESULTS: Mann-Whitney U test revealed a significant difference between the two groups. The patients of the tDCS group achieved a significant improvement in the post/pre ratio of auditory continuous performance test and visual continuous performance test on the SCNT items. CONCLUSION: Our results indicate that the concomitant use of the tDCS with CACR to the prefrontal cortex may provide additional beneficial effects in improving the cognitive dysfunction for patients with stroke.

Improvement of the Working Memory by Transcranial Direct Current Stimulation in Healthy Older Adults

OBJECTIVE: To investigate the short term effects of prefrontal transcranial direct current stimulation (tDCS) in healthy older adults aged more than 65 years by means of verbal and visuospatial working memory tasks. METHOD: Twenty four healthy older adults (14 males and 10 females, age range: 65-78 years old) were enrolled in this study. A double-blind study was conducted. The subjects underwent sham or anodal tDCS over the left prefrontal cortex (F3 in the international 10-20 EEG system). DC was delivered for 30 minutes at 2 mA with 25 cm2 saline-soaked sponge electrodes. A cathode electrode was applied to the left arm. Before and after tDCS, the subjects performed 2-back verbal working memory and visuospatial memory tasks. The rates of improvement of the accuracy and the reaction time were analyzed. RESULTS: On the 2-back verbal working memory tasks, the verbal working memory accuracy was improved in the real group compared with that of the sham group. On visuospatial working memory task, the working memory accuracy and reaction time were not improved in either the real group or the sham group. CONCLUSION: The results showed beneficial effects of noninvasive anodal tDCS on the cognitive function in healthy older adults. We suggest that tDCS induces functional changes on the left prefrontal cortex, and it improves the age-related cognitive impairment in the healthy elderly population.

Improvement of Hand Function with Transcranial Direct Current Brain Polarization in Stroke Patients

OBJECTIVE: To investigate therapeutic effects of anodal direct current (DC) polarization on the primary motor cortex in subacute and chronic stroke patients by measuring changes of hand function and corticospinal excitability before and after stimulation. METHOD: Fourteen subacute and chronic stroke patients were included in this study. This study was designed as a sham-controlled, double-blind, and crossover experiment. The anode was positioned on the primary motor cortex of the affected hemisphere. The primary motor cortex was identified using transcranial magnetic stimulation (TMS), the motor evoked potentials (MEPs) were recorded by surface electrodes placed over the contralateral first dorsal interosseous muscle. DC was delivered for 20 minute at 2 mA with 25 cm2 saline-soaked sponge electrodes. Before and after DC polarization, we checked the box and block test, nine hole peg test, grip power, lateral prehension power, MEPs amplitude, and MEPs latency. RESULTS: The box and block test, grip power, lateral prehension power, and MEPs amplitude increased after anodal DC to primary motor cortex (p <0.05). Positive correlation showed between improvement of box and block test and change of MEPs amplitude (r=0.808, p=0.001). CONCLUSION: Increased hand functions and the corticospinal tract excitability were obtained by 2 mA, 20 minute anodal DC polarization. Anodal DC polarization to primary motor cortex may play a potential role for facilitating the corticospinal tract thereby enhancing hand motor recovery in stroke patients.

Improvement of Apraxia and Hand Function with Transcranial Direct Current Brain Polarization in Patients with Corticobasal Degeneration

OBJECTIVE: To see whether anodal direct current (DC) polarization of the inferior parietal cortex (IPC) and the primary sensorimotor area (SM1) in corticobasal degeneration (CBD) patients leads to improvement of praxia and finger motion. METHOD: Twelve patients with CBD were enrolled. This single blind crossover study had three arms, anodal DC to IPC, anodal DC to SM1, and shame polarization on occipital area. DC was delivered for 40 minute at 2 mA with 25 cm2 sponge electrodes. Before and 20 min after the start of polarization, we performed the test of oral and limb apraxia (TOLA), finger tapping frequency, and grooved pegboard test. RESULTS: The total score of TOLA was increased 5.4+/-2.3% after anodal DC to IPC. The scores of limb apraxia and picture gesture subtests of TOLA, not of oral apraxia subtest, increased significantly after anodal DC to IPC compared to sham DC polarization (p<0.05). In anodal DC to SM1 group, the finger tapping frequency increased 15.5+/-14.1%, which was significantly greater than in sham group (p<0.05). CONCLUSION: These results showed beneficial effects of anodal DC polarization on apraxia and hand function in CBD patients. In addition, these effects for apraxia and hand movement were dependent on their stimulation sites of brain.