After reading the abstracts obtained from a literature search of disease topic, describe each or respond to each item comprehensively and in detail.

After reading the abstracts obtained from a literature search of disease topic, describe each or respond to each item comprehensively and in detail. 

SERUM COPPER, ZINC, AND IRON LEVELS IN PATIENTS WITH ALZHEIMER’S DISEASE: A 

META-ANALYSIS OF CASE-CONTROL STUDIES.

Li DD1, Zhang W2, Wang ZY1, Zhao P1.

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.

1. What is the epidemiologic study design?

2. (a) Identify the exposure(s) of interest (independent variables) and (b) the 

outcome(s) (dependent variables) of interest in the study. 

3. (a) Suggest at least one possible bias (systematic error) that might be present in 

each study. Pay particular attention to how subjects were selected, and what 

information was gathered from them and how it was collected. (b) Explain 

specifically how this could introduce bias into the study.

4. (a) Suggest one or more possible confounding factors related to the data 

collected and analyzed in the study, and (b) explain how it/they might confound 

interpretation of the authors’ findings.

5. (a) Suggest at least one other epidemiologic study design that could address the 

same question(s), and (b) discuss the relative strengths and limitations of the 

other study design compared to the one actually used.