Dementia and cognitive impairment disease is a syndrome with acquired and persistent cognitive impairment as its core, and leads to the decline of daily life and work ability and behavior change of patients. There are many kinds of dementia and cognitive impairment diseases, including Alzheimer's disease (AD), vascular dementia, Lewy body dementia, frontotemporal dementia, and secondary dementia caused by other diseases. Among them, AD is the most common, accounting for 50% to 70% of all types of dementia[1]。 Based on the research progress of AD, the occurrence of dementia and cognitive impairment diseases is currently considered as a continuous pathophysiological process. There is also a pre-AD dementia stage before the AD dementia stage, including mild cognitive impairment (MCI) and preclinical stage. Mild cognitive impairment is when a patient has subjective or objective memory or cognitive impairment, but his ability to live daily life has not been significantly affected and has not yet reached the standard of dementia. The preclinical stage of AD is the earliest stage of AD. There are no clinical manifestations of cognitive impairment or only minor complaints of memory loss in this stage, which can be diagnosed by cerebrospinal fluid or imaging tests such as PET amyloid imaging[2]。 The stage in which the complaint of memory loss occurs is also called subjective cognitive decline.
