HP and infection: To investigate the relationship between the prognosis of individuals with Alzheimer's disease and Helicobacter pylori infection and the amyloid beta-protein and P181 levels in peripheral blood, from January 2019 to June 2020, 59 patients were included in this investigation, comprising 27 patients in the AD group and 32 patients in the normal control group, and we will investigate the impact of the patients' illness history and HP-negative and HP-positive infections.