ObjectiveTo systematically review the influence of dexmedetomidine on early postoperative cognitive dysfunction in adult patients after receiving noncardiac surgery under general anesthesia. MethodsThe randomized controlled trials (RCTs) about the influence of dexmedetomidine on the early postoperative cognitive dysfunction of patients after receiving noncardiac surgery with general anesthesia was searched in PubMed, EBSCO, Springer, Ovid, The Cochrane Library (Issue 1, 2013), CNKI, VIP, WanFang Data and Google Scholar up to November 30th, 2013. The references of included literature were also retrieved manually. Two reviewers independently screened literature according to the inclusion and exclusion criteria, extracted data, and assessed the methodological quality of included studies. Then meta-analysis was performed using RevMan 5.2. ResultsA total of 22 RCTs involving 1 356 patients were enrolled. The results of meta-analysis indicated that:a) dexmedetomidine reduced the incidence of postoperative cognitive dysfunction on the first day (RR=0.38, 95%CI 0.29 to 0.49, P < 0.001), on the seventh day (RR=0.55, 95%CI 0.23 to 1.29, P=0.17); improved postoperative MMSE scores after surgery (on the first day:MD=2.38, 95%CI 1.42 to 3.34, P < 0.001; on the seventh day:MD=0.92, 95%CI 0.16 to 1.68, P=0.02), and decreased the expression of inflammatory factor IL-6 (instant:MD=-11.96, 95%CI-18.45 to-5.46, P=0.000 3; after 24 h:MD=-7.50, 95%CI-13.73 to-1.27, P=0.02); and TNF-α (instant:MD=-4.09, 95%CI-7.02 to-1.16, P=0.006)) in patients. b) No significant difference was found between two groups (MD=-0.97, 95%CI-2.37 to 0.43, P=0.17). ConclusionDexmedetomidine can effectively reduce the early-stage postoperative cognitive dysfunction, improve MMSE scores after the operation, and reduce inflammatory reaction. In addition, due to the limited quantity and quality of studies included, larger sample, high quality RCTs are needed to verify the abovementioned conclusion.