Review criteria: how did you gather the information you considered in your review?
We searched PubMed, Cochrane library, Web of Science, China National Knowledge Infrastructure(CNKI), Wanfang, China Biology Medicine disc (CBM), and Weipu database for the study on the association between blood pressure variability and cognitive function. Retrieval time limit was from the date of establishment of each database to July 15, 2021. Two researchers independently searched and screened relevant documents. The search results were imported into Endnote for double-checking, and then the initial screening was carried out based on the abstracts of the literature to eliminate irrelevant or unusable documents.