[New diagnostic guidelines for Alzheimer's disease by NIA/AA].

In 2011, the National Institute on Aging and the Alzheimer's Association (NIA/AA) published new guidelines for the diagnosis of Alzheimer's disease (AD) twenty-seven years after old guidelines had been published. The working groups recognized the whole clinical trajectory of AD as consisting of three defined stages, namely, AD dementia, mild cognitive impairment due to AD and preclinical AD. In addition to some refinements of descriptions of clinical features, based on recent scientific evidences of biomarkers, biomarker evidence was incorporated into the diagnostic criteria for AD dementia and mild cognitive impairment(MCI) due to AD to enhance diagnostic accuracy in research settings. Preclinical AD is newly defined as the earliest phase with presence of biomarker evidence suggesting AD pathophysiology and completely absence of clinical manifestation or absence of clinical symptom above subtle cognitive decline which falls short of meeting criteria for MCI. The diagnostic criteria enable disease modifying drug trials for subjects with earlier stage of AD pathology. Note that these criteria incorporating biomarker evidence are solely intended for research purposes. Further biomarker researches targeting subjects with early stage, especially preclinical AD are needed for refinement and broader usage of new guidelines.