Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the formation of β -amyloid (Aβ) plaques, intracellular aggregation of microtubule-associated protein Tau (Tau), and loss of neurons and synapses. With the development of population aging, the incidence of AD is increasing year by year, which brings a huge economic burden to society. At present, the diagnosis of AD is still difficult. Body fluid biomarkers are essential for accurate and early diagnosis of AD and serve as a prerequisite for effective treatment of the disease.