The diagnostic criteria for Alzheimer Disease （AD） have evolved from the initial diagnostic criteria in 1984 to the research framework of AD based on ATN classification system in 2018. The constant updating of diagnostic criteria has made us more aware of the disease of AD， as well as early diagnosis and biomarkers. The concept that AD is a continuous disease spectrum has been deeply rooted in people's minds， and the inclusion of biomarkers has led to the advancement of disease diagnosis. Early detection， early diagnosis and early intervention in the early stage of AD will bring new hope for the study of AD.