[Overview on Alzheimer's disease].

It is now one hundred years since the first publication on Alzheimer's disease by Alois Alzheimer. Since 1980's deciphering Alzheimer's disease has greatly quickened, and investigators currently think that it becomes possible to treat or prevent Alzheimer's disease that is the major socioeconomical concern in all the developed countries. We owe this current understanding to three major advances, development of Abeta vaccination and gamma-modifiers, and a series of large-scale prospective studies. J-ADNI is being undertaken from this fall, which follows the protocols by US-ADNI. The major goal is establishment of the surrogate marker for AD based on MRI data. In addition, this project would provide more clarification of MCI and dementia themselves and their differentiation. In view of the temporal profile of Alzheimer disease, it is essential to detect at-risk people who carry senile plaques (amyloid) but are cognitively normal. Even in MCI more than 50% of neurons in layer 2 is already lost. For such very early detection of at-risk people biomaker would be helpful. According to sink hypothesis, there is chemical equilibrium of Abeta between in plasma, CSF and senile plaques. Thus what we should do is to find insoluble Abeta-specific fragments or modifications in the peripheral blood.