Peripheral inflammatory markers in the patients with mild cognitive impairment: a meta-analysis

Objective To evaluate the association of peripheral blood inflammatory cytokines with mild cognitive impairment (MCI). Methods Databases including Pubmed, Cochrane library, Ovid, Web of science, CNKI, CBM, VIP and Wan Fang were retrieved to collect case-control studies related to the concentration of inflammatory cytokines in peripheral blood of MCI. After extracting data and appraising the quality of the included studies, meta-analysis were conducted using RevMan 5.3 and CMA 3.0. Results The levels of CRP, TNF-α, IL-1, MCP-1 and M-CSF and other 9 kinds of inflammatory factors in 33 studies were included in the analysis. A total of 8 742 subjects were enrolled, including 2 398 patients and 6 344 controls. The Meta-analysis showed that the levels of CRP (SMD=0.87, 95%CI (0.48, 1.26), P<0.0001), TNF-α(SMD=1.16, 95%CI (0.32, 2.00), P=0.007), IL-1β (SMD=0.96, 95%CI (0.17, 1.76), P=0.02), IL-6 (SMD=1.07, 95%CI (0.53, 1.61), P<0.0001), IL-8 (SMD=1.65, 95%CI (0.36, 2.93), P=0.01) in peripheral blood of patients with MCI were significantly higher than that of normal control group; however, there was no statistical difference between the two groups in the levels of IL-10, IL-12, MCP-1 and M-CSF. Conclusion The patients with MCI has a higher levels of CRP, TNF-α, IL-1β, IL-6 and IL-8 in peripheral blood, which suggesting that these inflammatory factors may be related to the occurrence and development of AD. Key words: Mild cognitive impairment; Inflammatory cytokines; Meta-analysis