Study of tDCS for Mild Cognitive Impairment

Inclusion Criteria: * Subjects who have a subjective memory impairment * Subjects who have Korean version of Mini Mental Status Examination score 22 or more * Subjects who have SVLT and RCFT delayed recall test scores lower than 1.5SD * Subjects who have had other cognitive impairments besides memory * Subjects who have Seoul-Instrumental Activities of Daily Living score (S-IADL) of 8 or lower * Subjects who are not dementia of Alzheimer's type * Subjects who are right-handed * Subjects who are able to read and write * Subject or legally responsible caregiver has provided informed consent Exclusion Criteria: * Subjects who have a history of stroke and seizures * Subjects who have any illnesses that may disturb the patients completing the trials, including stroke, Parkinson's disease, type 1 diabetes, uncontrollable high blood pressure, Huntington's disease, cerebral palsy, liver failure, nephritis, encephalitis, meningitis, scleroma, seizures and a treatment ischemic attack. * Subjects who have neurologic problems on physical examination that cuase memory disturbances * Subjects who have a history of DSM-IV Axis I disorders * Subjects who have extremely sensitive skin * Subjects who have suffered from the cancer in 3 years * Subjects who have had a cerebrovascular neurosurgery in medical history * Subjects who have dyspnea in sitting position * Subjects who have problems with memory, language and problem-solving for 2 hours after the heart attack. * Subjects who have a history of drug or alcohol abuse (in the past 5 years) * Subjects who have a history of mental or emotional disorders (in the past 5 years) * Subjects who have been lapsed into unconsciousness for an hour because of other reasons than general anesthesia * Subjects who have a history of hospitalization due to head injury * Subjects who are unable to read even with glasses * Subject who are unable to understand the conversation due to the hearing defect (even with the hearing aid)