One hundred years has passed since the appearance of the first article on Alzheimer’s disease（AD）,by Alois Alzheimer. AD is the most common form of dementia,accounting for over 50% of all dementia and affecting more than 26 million people worldwide. Since the 1980s, the pace of research into the nature of AD has greatly accelerated, and investigators currently believe that it will become possible to treat or prevent AD, which is a major socioeconomic concern in all developed countries of the world.
 Mild cognitive impairment（MCI）is a relatively recent term used to describe people who have some memory problems,but do not actually have dementia. In recent years,some drug treatments that can improve the symptoms of AD have become available. Other treatments that may slow down the progression of AD in the brain are also being developed. It is important that people with AD be identified as early as possible,so that they can benefit from these treatments in the future. Identifying people with MCI is one way to try to achieve this.
 In Japan, the Japanese Alzheimer’s Disease Neuroimaging Initiative（J-ADNI）was launched in 2008. It follows the protocols established by US-ADNI, and aims to conduct a longitudinal workup of standardized neuroimaging, biomarker, and clinico-psychological surveys. The Japanese research protocol was designed to maximize compatibility with that of US-ADNI, including structural magnetic resonance imaging（MRI）analysis for the evaluation of brain atrophy, fluorodeoxyglucose（FDG） and amyloid positron emission tomography（PIB-PET）,cerebrospinal fluid（CSF）sampling,and APOE genotyping,as well as a set of clinical and psychometric tests that were prepared so as to achieve the greatest compatibility possible with those used in US-ADNI. J-ADNI has recruited approximately 357 participants（142 with amnestic mild cognitive impairment, some 134 elders without impairment, and 72 persons with mild Alzheimer’s disease）as of April 15, 2010.
 Worldwide ADNI activities will allow the establishment of rigorous quantitative descriptions of the natural course of AD in its very early stages. In addition,this project will aid in the clarification and differentiation of MCI and AD.
 The major goal of this research is the establishment of surrogate markers for AD based on MRI,PET,and CSF data. This data,as well as the methodologies and infrastructure used, will facilitate clinical trials of disease-modifying therapies for AD using surrogate biomarkers, enabling the application of effective therapies with AD/MCI patients,and eventually the prevention of AD.
 In this symposium, I will speak about MCI and early-stage AD,with a particular focus on the latest clinical neuroimaging data from J-ADNI.