Alzheimer's disease (AD) is becoming a growing global problem, and there is an urgent need to identify reliable blood biomarkers of the risk and progression of this condition. A potential candidate is the brain-derived neurotrophic factor (BDNF), which modulates major trophic effects in the brain. However, findings are apparently inconsistent regarding peripheral blood BDNF levels in AD patients vs. healthy people. We thus performed a systematic review and meta-analysis of the studies that have examined peripheral BDNF levels in patients with AD or mild cognitive impairment (MCI) and healthy controls. We searched articles through PubMed, EMBASE, and hand searching. Over a total pool of 2061 potential articles, 26 met all inclusion criteria (including a total of 1584 AD patients, 556 MCI patients, and 1294 controls). A meta-analysis of BDNF levels between early AD and controls showed statistically significantly higher levels (SMD [95 

作者：Bo Yi, Kim；Seon Heui, Lee；Petra L, Graham；Francesco, Angelucci；Alejandro, Lucia；Helios, Pareja-Galeano；Thomas, Leyhe；Yuda, Turana；I Re, Lee；Ji Hye, Yoon；Jae Il, Shin

来源：Molecular neurobiology 2016 年