Abstract
Background: Many publications have investigated the association between metal ions and the risk of Alzheimer's disease (AD), but the results were ambiguous.Aims: The objective of this study was to assess the association between the serum levels of metals (copper/zinc/iron) and the risk of AD via meta-analysis of case-control studies.Methods: We screened literatures published after 1978 in the Pubmed, Embase, Cochrane library, Web of Science and ClinicalTrials.gov. Electronic databases. By using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, we performed a systematic review of the 407 publications, there are 44 of these publications met all inclusion criteria. The Review Manager 5.3 software was used to calculate available data from each study.Results: Consistent with the conclusions of other meta-analysis, our results demonstrated serum copper levels were significantly higher [MD = 9.27, 95% CI (5.02–13.52); p < 0.0001], and the serum zinc levels were significantly lower in AD patients than in healthy controls [MD = −6.12, 95% CI (−9.55, −2.69); p = 0.0005]. Serum iron levels were significantly lower in AD patients than in healthy controls after excluded two studies [MD = −13.01, 95% CI (−20.75, −5.27); p = 0.001].Conclusion: The results of our meta-analysis provided rigorous statistical support for the association of the serum levels of metals and the risk of AD, suggesting a positive relationship between the serum copper levels and AD risk, and a negative relationship between the serum zinc/iron levels and AD risk.
Highlights
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that leads to intellectual decline including memory loss, and language breakdown (International, 2009)1
We searched for case-control studies articles published from 1978 to May 2016 via systematically screening in the PUBMED, EMBASE, Cochrane library, Web of science and clinical trials.gov electronic databases according to PRISMA guidelines (Moher et al, 2010) by using the following search terms In the keywords “Alzheimer’s disease”(or “AD”), “copper”, “zinc”, “iron”, “metals.” Additional studies were obtained from the reference lists of identified studies
According to PRISMA guideline (Moher et al, 2010), we choose the following inclusion criteria for the meta-analyses: (1) full-text publications written in English; (2) case-control studies about the association of Cu, Zn, and Fe with the AD; (3) studies providing the serum level of Cu, Zn, and Fe to calculate the mean difference (MD) or standardized mean difference (SMD) and 95% confidence intervals (CIs)
Summary
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that leads to intellectual decline including memory loss, and language breakdown (International, 2009). Aims: The objective of this study was to assess the association between the serum levels of metals (copper/zinc/iron) and the risk of AD via meta-analysis of case-control studies. Results: Consistent with the conclusions of other meta-analysis, our results demonstrated serum copper levels were significantly higher [MD = 9.27, 95% CI (5.02–13.52); p < 0.0001], and the serum zinc levels were significantly lower in AD patients than in healthy controls [MD = −6.12, 95% CI (−9.55, −2.69); p = 0.0005]. Conclusion: The results of our meta-analysis provided rigorous statistical support for the association of the serum levels of metals and the risk of AD, suggesting a positive relationship between the serum copper levels and AD risk, and a negative relationship between the serum zinc/iron levels and AD risk
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