Abstract:Alzheimer's Disease (AD) is the most common cause of dementia in the elderly, which has become an important social public health problem. However, the diagnosis and treatment rates of AD in China are still low, and the public's awareness of AD is scarce. The early onset of AD is insidious and not easy to detect. When the symptoms of obvious cognitive dysfunction appear in the clinical stage of dementia, the disease is already severe. At this time, the treatment effect is not satisfactory. This paper makes a comprehensive introduction and comparison of the early diagnosis methods of AD, including neuropsychological examination, imaging examination and biomarker examination, and introduces the evolution of the definition and diagnostic criteria of AD. In recent years, in the clinical diagnosis of AD, the combination of multiple diagnostic methods is more inclined to improve the quality of diagnosis. With the evolution of the definition and diagnostic criteria for AD, the role of biomarker evidence has emerged, but the use of biomarkers in clinical practice remains controversial, and further standardization and verification are needed.