Department of Toxicology, School of Public Health, Shandong University, Jinan, China.
Department of Epidemiology, School of Public Health, Shandong University, Jinan, China.
J Alzheimers Dis. 2018;62(1):361-372. doi: 10.3233/JAD-170811.
Environmental exposure to toxic metals has been postulated to play a role in the pathophysiological processes of Alzheimer's disease (AD). However, the circulatory levels of toxic metals in AD patients are not consistent in previous studies.
To systematically assess levels of toxic metals (aluminum, mercury, cadmium, lead) in the circulation (blood, serum/plasma) of AD patients and controls.
PubMed, Web of Science, Science Direct, Cochrane Library, and the China National Knowledge Infrastructure (CNKI) were systematically searched to identify studies published up to January 1, 2017. Meta-analyses were performed using random-effects models and the pooled standardized mean difference (SMD) were reported with 95% confidence intervals (CI).
We identified 17, 7, 8, and 10 studies for aluminum, mercury, cadmium, and lead, respectively. Meta-analyses showed significantly elevated circulatory levels of aluminum (SMD = 1.08, 95% CI: 0.66, 1.50), mercury (SMD = 0.55, 95% CI, 0.15, 0.95), and cadmium (SMD = 0.62, 95% CI: 0.12, 1.11), whereas lower levels of lead (SMD = -0.23, 95% CI: -0.38, -0.07) in AD patients than in controls. Publication bias was only observed for aluminum studies, but the "trim and fill" analysis showed that the publication bias did not alter the direction of the effect. Sensitivity analyses showed no studies from the pooled analysis changed the results.
Compared to controls, circulatory levels of aluminum, mercury, and cadmium are significantly higher but the levels of lead were reduced in AD patients. These findings suggest that elevated aluminum, mercury, and cadmium in the circulation, especially in serum may play a role in the progression of AD.
环境暴露于有毒金属被认为在阿尔茨海默病（AD）的病理生理过程中起作用。然而，在以前的研究中，AD 患者循环中的有毒金属水平并不一致。
系统评估 AD 患者和对照者循环（血液、血清/血浆）中有毒金属（铝、汞、镉、铅）的水平。
系统检索 PubMed、Web of Science、Science Direct、Cochrane Library 和中国知网（CNKI），以识别截至 2017 年 1 月 1 日发表的研究。使用随机效应模型进行荟萃分析，并报告合并标准化均数差（SMD）及其 95%置信区间（CI）。
我们分别确定了 17、7、8 和 10 项关于铝、汞、镉和铅的研究。荟萃分析显示，AD 患者的循环铝水平显著升高（SMD=1.08，95%CI：0.66，1.50）、汞（SMD=0.55，95%CI：0.15，0.95）和镉（SMD=0.62，95%CI：0.12，1.11），而循环铅水平较低（SMD=-0.23，95%CI：-0.38，-0.07）。仅观察到铝研究存在发表偏倚，但“修剪和填充”分析表明，发表偏倚并未改变效应的方向。敏感性分析显示，没有任何研究改变了汇总分析的结果。
与对照组相比，AD 患者的循环铝、汞和镉水平明显升高，但铅水平降低。这些发现表明，循环中尤其是血清中的铝、汞和镉水平升高可能在 AD 的进展中起作用。
