Objective To investigate the prevalence and factors of Alzheimer disease in the urban area of Dongguan.Methods 2348 residents from 28 communities in Dongguan were spot-checked by multistage random cluster sampling method.And univariate and multivariate analysis were used to analyze the factors influencing Alzheimer disease.Results Univariate analysis showed that the main factors affecting the incidence of Alzheimer disease were age,whether living alone,character,education level,whether having genetic history,and whether doing exercise.The multivariate analysis showed that the independent factors affecting the incidence of Alzheimer disease were age,whether living alone,character,education level,whether having genetic history,and whether doing exercise.Conclusions If one is in advanced age,lives alone,introverted,has low educational level,is lack of exercise,or has genetic history,he/she has a high possibility having Alzheimer disease.