Objectives  To comprehensively evaluate the effect of exercise on the cognitive function of Alzheimer's disease(AD) patients and to explore the optimal program of exercise prevention and treatment for AD patients by comparing the effects of different types and frequencies of exercise on the cognitive function in AD patients.

  Methods  Databases such as PubMed, SCI, MEDLINE and CNKI were searched for relevant randomized controlled trials. The retrieval time was from the date of database construction to December 2018, literature was screened according to the inclusion and exclusion criteria, and the data were extracted after evaluating the quality of research methods to include the literature.

  Results  Through screening, 15 pieces of literature were used including the data of 774 patients with AD. Meta-analysis results show that the combined effect size of exercise effects on the cognitive function in patients with AD falls on the right side of the invalid lineMD=1.27, 95%CI(0.77, 1.78), P < 0.000 01. The combined effect size of combined aerobic and anaerobic exerciseMD=1.38, 95%CI(0.09, 2.67), P=0.04 is greater than the simple aerobic exerciseMD=1.26, 95%CI(0.70, 1.81), P < 0.000 01, and the combined effect size of high frequency exerciseMD=1.71, 95%CI(0.11, 3.30), P=0.04 greater than the low frequency exerciseMD=1.60, 95%CI(0.86, 2.34), P < 0.000 1.

  Conclusions  Exercise can effectively improve the cognitive function of AD patients; The intervention effect of combined aerobic and anaerobic exercises is better than that of aerobic exercise alone. And the intervention effect of the high frequency exercise is better than that of the low frequency exercise.