Clinical Research Center for Dementia of South Korea (CREDOS)(or CRCD) (CREDOS)

1. Patient populatin who is suffering from memory impairment
2. Normal subjects matched with age and gender

Inclusion Criteria:

• Alzheimer's disease(AD) and mild cognitive impairment(MCI)will be enrolled in the study.

  1. the diagnostic criteria of Alzheimer's disease(AD) according to DSM IV or NINCDS -ADRDA
  2. the diagnostic criteria of mild cognitive impairment(MCI) A. Memory or other cognitive complaint preferably corroborated by an informant B. Objective memory impairment or other cognitive for age and education C. Largely intact general cognitive function D. Essentially preserved ADL E. Not demented

Exclusion Criteria:

• Exclusion criteria are current neurological or other psychiatric disorders, as well as a history of epileptic seizures, substantial brain damage or neurosurgical operation, according to established safety criteria.