Elevated serum copper and ceruloplasmin levels in Alzheimer's disease

Cognitive and metabolic signatures of early and late-onset depression: A comparative study

BACKGROUND

Early-onset depression (EOD) and late-onset depression (LOD) are prevalent subtypes of major depressive disorder (MDD), but the clinical distinction between EOD and LOD remains blurred due to nonspecific symptoms and lack of biomarkers. This study aims to elucidate the characteristics in cognitive function and biochemical metabolism of EOD and LOD, and to identify biological factors influencing age of onset (AOO).

METHODS

Seventy patients with MDD (40 with EOD and 30 with LOD) and sixty-eight age-matched healthy controls (HC) were included in this study. Participants were evaluated for clinical features, cognitive function, and serum trace elements levels. Proton magnetic resonance spectroscopy (1H-MRS) was employed to quantify neurometabolites levels, including N-acetyl aspartate (NAA), choline (Cho), and creatine (Cr).

RESULTS

Patients with LOD experienced more episodes and severe depressive symptoms than those with EOD (p = 0.025, p < 0.001). EOD patients performed significantly worse than LOD patients on social cognition (p = 0.005), while LOD patients performed worse than EOD patients on reasoning and problem solving (p = 0.005). Additionally, LOD patients displayed higher ceruloplasmin (Cp) levels compared to EOD patients (p = 0.004), but no difference was found in neurometabolic levels between EOD and LOD. Multiple linear regression indicated a positive correlation between serum Cp levels and AOO of depression (p < 0.001), while bilateral thalamic NAA/Cr showed a negative correlation with AOO (p = 0.012, p = 0.016).

CONCLUSIONS

Patients with EOD were characterized by social cognition impairments, while patients with LOD were marked by reasoning and problem-solving deficits. Serum Cp levels demonstrated an AOO-related effect and served as a positive predictor for the AOO of depression. Furthermore, a negative correlation has been established between bilateral thalamic NAA/Cr and the AOO of MDD.

LIMITATIONS

The limited sample size and the challenge in distinguishing whether observed results are attributed to age or AOO effects.

Alteration of ceruloplasmin in patients with malaria: a systematic review and meta-analysis of observational studies

BACKGROUND

The evidences of oxidative stress-related Plasmodium infection may alter the ceruloplasmin levels were inconsistent. This systematic review and meta-analysis aimed to collate and synthesize literatures on malaria and ceruloplasmin concentrations.

METHODS

The systematic review has been registered with PROSPERO (CRD42023454859). Six electronic databases were systematically searched for investigated ceruloplasmin levels in malaria: ProQuest, EMBASE, MEDLINE, Ovid, PubMed, and Scopus, from their inception to August 2023. The quality of the included studies was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools for cross-sectional, cohort, and case-control studies. Qualitative synthesis was undertaken to summarize findings from the included studies. For quantitative synthesis, a meta-analysis was performed using random-effects models.

RESULTS

A total of 411 articles were retrieved, and nine studies were included in the review. The majority of included studies found significantly increased ceruloplasmin levels in malaria patients compared to uninfected controls. The meta-analysis showed a significant increase of ceruloplasmin in patients with malaria as compared to uninfected controls (P < 0.01, Hedge's g 1.18, 95% CI 0.90-1.47, I2 59.19%, eight studies).

CONCLUSION

The systematic review and meta-analysis consistently revealed a significant rise in ceruloplasmin levels among malaria patients. Further research is essential to understand the variations in ceruloplasmin levels between different Plasmodium species and the severity of malaria in patients.

Effects of mixed metal exposures on MRI diffusion features in the medial temporal lobe

Background

Environmental exposure to metal mixtures is common and may be associated with increased risk for neurodegenerative disorders including Alzheimer's disease.

Objective

This study examined associations of mixed metal exposures with medial temporal lobe (MTL) MRI structural metrics and neuropsychological performance.

Methods

Metal exposure history, whole blood metal, and neuropsychological tests were obtained from subjects with/without a history of mixed metal exposure from welding fumes (42 exposed subjects; 31 controls). MTL structures (hippocampus, entorhinal and parahippocampal cortices) were assessed by morphologic (volume, cortical thickness) and diffusion tensor imaging [mean (MD), axial (AD), radial diffusivity (RD), and fractional anisotropy (FA)] metrics. In exposed subjects, correlation, multiple linear, Bayesian kernel machine regression, and mediation analyses were employed to examine effects of single- or mixed-metal predictor(s) and their interactions on MTL structural and neuropsychological metrics; and on the path from metal exposure to neuropsychological consequences.

Results

Compared to controls, exposed subjects had higher blood Cu, Fe, K, Mn, Pb, Se, and Zn levels (p's<0.026) and poorer performance in processing/psychomotor speed, executive, and visuospatial domains (p's<0.046). Exposed subjects displayed higher MD, AD, and RD in all MTL ROIs (p's<0.040) and lower FA in entorhinal and parahippocampal cortices (p's<0.033), but not morphological differences. Long-term mixed-metal exposure history indirectly predicted lower processing speed performance via lower parahippocampal FA (p=0.023). Higher whole blood Mn and Cu predicted higher entorhinal diffusivity (p's<0.043) and lower Delayed Story Recall performance (p=0.007) without overall metal mixture or interaction effects.

Discussion

Mixed metal exposure predicted MTL structural and neuropsychological features that are similar to Alzheimer's disease at-risk populations. These data warrant follow-up as they may illuminate the path for environmental exposure to Alzheimer's disease-related health outcomes.

The impact of serum copper on the risk of epilepsy: a mendelian randomization study

BACKGROUND

The relationship between serum copper and epilepsy has been elucidated in observational studies. In this study, we aimed to explore the causal relationship between serum copper and epilepsy using Mendelian randomization (MR) analysis.

METHODS

Single nucleotide polymorphisms (SNPs) associated with serum copper were used as instrumental variables for MR analysis to evaluate their causal effects on epilepsy. The main MR results were obtained by using the inverse variance weighting (IVW) method, supplemented by weighted median and MR-Egger regression. In addition, sensitivity analyses such as Cochran's Q test and pleiotropy test were used to assess these SNPs on epilepsy in terms of horizontal pleiotropy and heterogeneity.

RESULTS

The IVW method revealed that the serum copper was associated with an increased risk of generalized epilepsy (OR= 1.07; 95% CI 1.01- 1.14; P = 0.032), and the sensitivity analysis further supports the robustness of the results.

CONCLUSIONS

The current study reveals a possible causal role for serum copper in increasing the risk of generalized epilepsy, which provide guidance for identifying potential risk factors for epilepsy.

Melatonin ameliorates chronic copper-induced lung injury

Copper (Cu) is an important trace element required for several biological processes. The use of copper is increasing gradually in several applications. Previous studies suggest that excess levels of copper are attributed to induce oxidative stress and inflammation, mediating tissue damage. Inline, melatonin the hormone of darkness has been reported to exhibit various therapeutic effects including strong free radical scavenging properties and anti-inflammatory effects. However, its effects against pulmonary injury promoted by copper are not explored and remain unclear so far. Therefore, the present study was aimed to investigate the protective effect of melatonin against copper-induced lung damage. Female Sprague Dawley (SD) rats were exposed to 250 ppm of copper in drinking water for 16 weeks and treated with melatonin (i.p.) 5 and 10 mg/kg from the week (13-16th). The extent of tissue damage was assessed by tissue oxidative stress parameters, metal estimation and histological analysis. Copper-challenged rats showed altered oxidative stress variables. In addition, metal analysis revealed increased copper accumulation in the lungs and histological staining results further indicated severe tissue injury and inflammatory cell infiltration in copper-exposed rats. To this side, treatment with melatonin showed antioxidant and anti-inflammatory activities evidenced by reduced oxidative stress, tissue inflammation and collagen deposition as compared to copper-exposed animals. Moreover, spectral findings suggested melatonin treatment modulated the frequency sift, as compared to copper-challenged animals. Altogether, the present results suggest that melatonin might play a potential role in preventing copper-induced lung aberrations via inhibiting the ROS-mediated oxidative stress and inflammation.

Trace elements and Alzheimer dementia in population-based studies: A bibliometric and meta-analysis

Alterations in the concentrations of trace elements may play a vital role in Alzheimer dementia progression. However, previous research results are inconsistent, and there is still a lack of review on the relationship between all the studied-trace elements and AD from various perspectives of population-based studies. In this study, we systematically reviewed previous population-based studies and identified the altered trace elements in AD patients. We searched the Web of Science Core Collection, PubMed, and Scopus database, and ultimately included 73 articles. A bibliometric analysis was conducted to explore the evolution of the field from an epidemiological perspective. Bibliometric data such as trace elements, biological materials, detection methods, cognitive tests, co-occurrence and co-citation statistics are all analyzed and presented in a quantitative manner. The 73 included studies analyzed 39 trace elements in total. In a further meta-analysis, standardized mean differences (SMDs) of 13 elements were calculated to evaluate their altered in AD patients, including copper, iron, zinc, selenium, manganese, lead, aluminum, cadmium, chromium, arsenic, mercury, cobalt, and manganese. We identified four trace elements-copper (serum), iron (plasma), zinc (hair), and selenium (plasma)-altered in AD patients, with SMDs of 0.37 (95% confidence interval [CI]: 0.10, 0.65), -0.68 (95% CI: -1.34, -0.02), -0.35 (95% CI: -0.62, -0.08), and -0.61 (95% CI: -0.97, -0.25), respectively. Finally, we formed a database of various trace element levels in AD patients and healthy controls. Our study can help future researchers gain a comprehensive understanding of the advancements in the field, and our results provide comprehensive population-based data for future research.

Dietary Intake Levels of Iron, Copper, Zinc, and Manganese in Relation to Cognitive Function: A Cross-Sectional Study

Background: Previous studies have related circulating levels of trace metal elements, of which dietary intake is the major source, to cognitive outcomes. However, there are still relatively few studies evaluating the associations of dietary intake levels of iron, copper, zinc, and manganese with cognitive function (CF). Methods: We leveraged the data of 6863 participants (mean [standard deviation] age = 66.7 [10.5] years) in the Health and Retirement Study (2013/2014). Dietary intake levels of iron, copper, zinc, and manganese were calculated from a semi-quantitative food frequency questionnaire. CF was assessed using the 27-point modified Telephone Interview for Cognitive Status (TICS). We used linear regression models to calculate the mean differences in global CF scores by quintiles of dietary intake levels of trace metal elements. Results: Among the study participants, the mean (SD) values of daily dietary intake were 13.3 (6.3) mg for iron, 1.4 (0.7) mg for copper, 10.7 (4.6) mg for zinc, and 3.3 (1.6) mg for manganese. Compared with the lowest quintile of dietary iron intake (<8.1 mg), the highest quintile (≥17.7 mg) was associated with a lower cognitive score (-0.50, -0.94 to -0.06, P-trend = 0.007). Higher dietary copper was significantly associated with poorer CF (P-trend = 0.002), and the mean difference in cognitive score between extreme quintiles (≥1.8 vs. <0.8 mg) was -0.52 (95% confidence interval: -0.94 to -0.10) points. We did not observe significant associations for dietary intake of zinc (P-trend = 0.785) and manganese (P-trend = 0.368). Conclusion: In this cross-sectional study, higher dietary intake of iron and copper was related to worse CF, but zinc and manganese intake levels were not significantly associated with CF.

BNT-15: Revised Performance Validity Cutoffs and Proposed Clinical Classification Ranges

BACKGROUND

Abbreviated neurocognitive tests offer a practical alternative to full-length versions but often lack clear interpretive guidelines, thereby limiting their clinical utility.

OBJECTIVE

To replicate validity cutoffs for the Boston Naming Test-Short Form (BNT-15) and to introduce a clinical classification system for the BNT-15 as a measure of object-naming skills.

METHOD

We collected data from 43 university students and 46 clinical patients. Classification accuracy was computed against psychometrically defined criterion groups. Clinical classification ranges were developed using a z -score transformation.

RESULTS

Previously suggested validity cutoffs (≤11 and ≤12) produced comparable classification accuracy among the university students. However, a more conservative cutoff (≤10) was needed with the clinical patients to contain the false-positive rate (0.20-0.38 sensitivity at 0.92-0.96 specificity). As a measure of cognitive ability, a perfect BNT-15 score suggests above average performance; ≤11 suggests clinically significant deficits. Demographically adjusted prorated BNT-15 T-scores correlated strongly (0.86) with the newly developed z -scores.

CONCLUSION

Given its brevity (<5 minutes), ease of administration and scoring, the BNT-15 can function as a useful and cost-effective screening measure for both object-naming/English proficiency and performance validity. The proposed clinical classification ranges provide useful guidelines for practitioners.

The Associations of Dietary Copper With Cognitive Outcomes

Dietary copper intake may be associated with cognitive decline and dementia. We used data from 10,269 participants of the Atherosclerosis Risks in Communities Study to study the associations of dietary copper intake with 20-year cognitive decline and incident dementia. Dietary copper intake from food and supplements was quantified using food frequency questionnaires. Cognition was assessed using 3 cognitive tests at study visits; dementia was ascertained at study visits and via surveillance. Multiple imputation by chained equations was applied to account for the missing information of cognitive function during follow-up. Survival analysis with parametric models and mixed-effect models were used to estimate the associations for incident dementia and cognitive decline, respectively. During 20 years of follow-up (1996-1998 to 2016-2017), 1,862 incident cases of dementia occurred. Higher intake of dietary copper from food was associated with higher risk of incident dementia among those with high intake of saturated fat (hazard ratio = 1.49, 95% confidence interval: 1.04, 1.95). Higher intake of dietary copper from food was associated with greater decline in language overall (beta = -0.12, 95% confidence interval: -0.23, -0.02). Therefore, a diet high in copper, particularly when combined with a diet high in saturated fat, may increase the risk of cognitive impairment.

Current research status of blood biomarkers in Alzheimer's disease: Diagnosis and prognosis

Alzheimer's disease (AD), which mainly occurs in the elderly, is a neurodegenerative disease with a hidden onset, which leads to progressive cognitive and behavioral changes. The annually increasing prevalence rate and number of patients with AD exert great pressure on the society. No effective disease-modifying drug treatments are available; thus, there is no cure yet. The disease progression can only be delayed through early detection and drug assistance. Therefore, the importance of exploring associated biomarkers for the early diagnosis and prediction of the disease progress is highlighted. The National Institute on Aging- Alzheimer's Association (NIA-AA) proposed A/T/N diagnostic criteria in 2018, including Aβ42, p-tau, t-tau in cerebrospinal fluid (CSF), and positron emission tomography (PET). However, the invasiveness of lumbar puncture for CSF assessment and non-popularity of PET have prompted researchers to look for minimally invasive, easy to collect, and cost-effective biomarkers. Therefore, studies have largely focused on some novel molecules in the peripheral blood. This is an emerging research field, facing many obstacles and challenges while achieving some promising results.

Fluorescent Sensor for Copper(II) and Cyanide Ions via the Complexation-Decomplexation Mechanism with Di(bissulfonamido)spirobifluorene

A novel spirobifluorene derivative bearing two bissulfonamido groups is successfully synthesized by Sonogashira coupling. This compound exhibits a strong fluorescence quenching by Cu(II) ion in a 50% mixture between acetonitrile and 20 mM pH 7.0 N-(2-hydroxyethyl)piperazine-N'-ethanesulfonic acid (HEPES) buffer with a detection limit of 98.2 nM. However, this sensor also shows ratiometric signal shifts from blue to yellow in the presence of Zn(II), Pb(II), and Hg(II) ions. The static quenching mechanism is verified by the signal reversibility using ethylenediaminetetraacetic acid (EDTA) and the Stern-Volmer plots at varying temperatures. The Cu(II)-spirobifluorene complex shows a highly selective fluorescence enhancement upon the addition of CN- ion with the detection limit of 390 nM. The application of this complex for quantitative analysis of spiked CN- ion in real water samples resulted in good recoveries.

Copper Imbalance in Alzheimer's Disease: Meta-Analysis of Serum, Plasma, and Brain Specimens, and Replication Study Evaluating ATP7B Gene Variants

Evidence indicates that patients with Alzheimer's dementia (AD) show signs of copper (Cu) dyshomeostasis. This study aimed at evaluating the potential of Cu dysregulation as an AD susceptibility factor. We performed a meta-analysis of 56 studies investigating Cu biomarkers in brain specimens (pooled total of 182 AD and 166 healthy controls, HC) and in serum/plasma (pooled total of 2929 AD and 3547 HC). We also completed a replication study of serum Cu biomarkers in 97 AD patients and 70 HC screened for rs732774 and rs1061472 ATP7B, the gene encoding for the Cu transporter ATPase7B. Our meta-analysis showed decreased Cu in AD brain specimens, increased Cu and nonbound ceruloplasmin (Non-Cp) Cu in serum/plasma samples, and unchanged ceruloplasmin. Serum/plasma Cu excess was associated with a three to fourfold increase in the risk of having AD. Our replication study confirmed meta-analysis results and showed that carriers of the ATP7B AG haplotype were significantly more frequent in the AD group. Overall, our study shows that AD patients fail to maintain a Cu metabolic balance and reveals the presence of a percentage of AD patients carrying ATP7B AG haplotype and presenting Non-Cp Cu excess, which suggest that a subset of AD subjects is prone to Cu imbalance. This AD subtype can be the target of precision medicine-based strategies tackling Cu dysregulation.

MOF-derived porous ZnO-Co3O4 nanocages as peroxidase mimics for colorimetric detection of copper(ii) ions in serum

Sensitive detection of copper ions (Cu²⁺) in biological samples is extremely important since an abnormal level of Cu²⁺ is linked with many diseases. Herein, we demonstrated a novel turn-on colorimetric sensor for selective detection of Cu²⁺ both in buffered solution and serum samples based on porous bimetallic transition metal oxide nanocages (ZnO-Co₃O₄ NCs) as peroxidase mimics. The ZnO-Co₃O₄ NCs were prepared by using ZnCo-zeolitic-imidazolate-framework (ZnCo-ZIF) as precursors via direct calcination. With the high peroxidase-like activity, the obtained ZnO-Co₃O₄ NCs can catalyze the oxidation of tetramethylbenzidine (TMB) in the presence of H₂O₂ to form a blue colored product. The inhibition effect of cysteine (Cys) on the catalytic activity of ZnO-Co₃O₄ NCs and its strong binding ability toward Cu²⁺ enabled the ZnO-Co₃O₄ NCs/Cys system to be utilized for sensitive detection of Cu²⁺, in which the catalytic activity of ZnO-Co₃O₄ NCs/Cys can be recovered by the introduction of Cu²⁺ with an obvious color change of the solution. The linear range for Cu²⁺ determination was 2 to 100 nM with a detection limit of 1.08 nM. More importantly, this colorimetric sensor has been successfully applied to detect Cu²⁺ in serum without pretreatment. Our findings are expected to expand the scope of application of nanozyme and shed light on early disease diagnosis.

Comprehensive Proteomic Profiling of Urinary Exosomes and Identification of Potential Non-invasive Early Biomarkers of Alzheimer's Disease in 5XFAD Mouse Model

Background

Alzheimer’s disease (AD) is an incurable neurodegenerative disease characterized by irreversible progressive cognitive deficits. Identification of candidate biomarkers, before amyloid-β-plaque deposition occurs, is therefore of great importance for early intervention of AD.

Objective

To investigate the potential non-invasive early biomarkers of AD in 5XFAD mouse model, we investigate the proteome of urinary exosomes present in 1-month-old (before amyloid-β accumulation) 5XFAD mouse models and their littermate controls. Another two groups of 2 and 6 months-old urinary samples were collected for monitoring the dynamic change of target proteins during AD progression.

Methods

Proteomic, bioinformatics analysis, multiple reaction monitoring (MRM), western blotting (WB) or ELISA were performed for analyzing these urinary exosomes.

Results

A total of 316 proteins including 44 brain cell markers were identified using liquid chromatography tandem mass spectrometry. Importantly, 18 proteins were unique to the 5XFAD group. Eighty-eight proteins including 11 brain cell markers were differentially expressed. Twenty-two proteins were selected to be verified by WB. Furthermore, based on an independent set of 12 urinary exosomes samples, five in these proteins were further confirmed significant difference. Notably, Annexin 2 and Clusterin displayed significant decreased in AD model during the course detected by ELISA. AOAH, Clusterin, and Ly86 are also brain cell markers that were first reported differential expression in urinary exosomes of AD model.

Conclusion

Our data demonstrated that some urinary exosome proteins, especially Annexin 2 and Clusterin, as nanometer-sized particles, enable detection of differences before amyloid-β-plaque deposition in 5XFAD mouse model, which may present an ideal non-invasive source of biomarkers for prevention of AD.

MiADMSA abrogates chronic copper-induced hepatic and immunological changes in Sprague Dawley rats

Wilson disease (WD) is an autosomal-recessive disorder associated with the impaired copper metabolism, resulting in hepatic and neurologic manifestations. D-Pencillamine (DPA) is a first-line of treatment however, monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA), is gaining recognition recently as a future chelating agent of choice. We evaluated the effects of MiADMSA against copper-induced (20 mg/kg, orally, once, daily for 16 weeks) hepatic and immunological changes in the male Sprague Dawley (SD) rats. Copper overload increased the levels of pro-oxidant and concurrently decreased the levels of antioxidant enzymes in the liver. Increased oxidative stress triggered the up-regulation of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in the liver and down-regulated the anti-inflammatory cytokine IL-4. Altered liver function parameters as well as serum immunoglobulins' (IgG, IgA, IgE, and IgM) levels, were also noted. MiADMSA treatment restored most of copper altered biochemical and immunological changes. Further, the histopathological changes proved that MiADMSA treatment ameliorated copper induced hepatic injury. Infra red spectra of liver tissue indicated shift in the characteristic -OH peak during copper exposure while the shifting came to normal in MiADMSA administered rat liver. We conclude that MiADMSA could be a promising antidote for the chronic copper toxicity and possibly in the clinical management of WD.

Proteomics Analysis of Blood Serums from Alzheimer's Disease Patients Using iTRAQ Labeling Technology

Alzheimer' disease (AD) is the most common form of dementia affecting up to 6% of the population over the age of 65. In order to discover differentially expressed proteins that might serve as potential biomarkers, the serums from AD patients and healthy controls were compared and analyzed using the proteomics approach of isobaric tagging for relative and absolute quantitation (iTRAQ). For the first time, AD biomarkers in serums are investigated in the Han Chinese population using iTRAQ labeled proteomics strategy. Twenty-two differentially expressed proteins were identified and out of which nine proteins were further validated with more sample test. Another three proteins that have been reported in the literature to be potentially associated with AD were also investigated for alteration in expression level. Functions of those proteins were mainly related to the following processes: amyloid-β (Aβ) metabolism, cholesterol transport, complement and coagulation cascades, immune response, inflammation, hemostasis, hyaluronan metabolism, and oxidative stress. These results support current views on the molecular mechanism of AD. For the first time, differential expression of zinc-alpha-2-glycoprotein (AZGP1), fibulin-1 (FBLN1), platelet basic protein (PPBP), thrombospondin-1 (THBS1), S100 calcium-binding protein A8 (S100A8), and S100 calcium-binding protein A9 (S100A9) were detected in the serums of AD patients compared with healthy controls. These proteins might play a role in AD pathophysiology and serve as potential biomarkers for AD diagnosis. Specifically, our results strengthened the crucial role of Aβ metabolism and blood coagulation in AD pathogenesis and proteins related to these two processes may be used as peripheral blood biomarkers for AD.

Metallomics Applied to the Study of Neurodegenerative and Mental Diseases

Biochemical imbalances, provoked by aging or a secondary illness, might directly affect the brain, causing severe problems, such as loss of memory or alteration of behavior patterns. Brain disorders are usually classified as injuries (such as stroke, hematomas, and concussions), tumors, and neurodegenerative (such as Parkinson's and Alzheimer's diseases) and mental (such as depression, bipolar disorder, schizophrenia) diseases. As the pathophysiology of these illnesses is not completely established and multiple factors are involved, metallomics, a bioanalytical strategy that allows the detection of metal ions and metalloproteins in diverse biological matrices, is of extreme relevance in identifying which elements are affected by a disease and/or treatment. Thus, determining which element ions suffer disturbances in their homeostasis during the disease progress is relevant to understand the biochemical changes and propose new drug targets. In addition, it is well known that oxidative stress plays an important role in the development of pathological neurodegenerative and mental diseases, which may be caused by metal ion dyshomeostasis, so it is also important to understand endogenous antioxidant metalloprotein and metalloenzyme mechanisms in this regard. In this context, recent applications of metallomics in the study of neurodegenerative and mental disorders are discussed in this chapter, as well as future trends in this research area.

Serum Copper, Zinc, and Iron Levels in Patients with Alzheimer's Disease: A Meta-Analysis of Case-Control Studies

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.

Removal of elevated level of chromium in groundwater by the fabricated PANI/Fe3O4 nanocomposites

In this work, we report the reduction of chromium concentration in the polluted groundwater samples from Madurai Kamaraj University area, India, where the dissolved salts in groundwater are reported as serious health hazards for its inhabitants. The water samples have intolerable amounts of total dissolved solids (TDS) and chromium is a prominent pollutant among them. Chromium reduction was achieved by treating the polluted groundwater with PANI/Fe₃O₄ nanocomposites synthesized by in situ polymerization method. Further experimentation showed that the nanocomposites exhibit better chromium removal characteristics upon increasing the aniline concentration during the synthesis. We were able to reduce chromium concentration in the samples from 0.295 mg L^-1 to a tolerable amount of 0.144 mg L^-1. This work is expected to open doors for chromium-free groundwater in various regions of India, when improved to an industrial scale.

Association Between Serum Ceruloplasmin Specific Activity and Risk of Alzheimer's Disease

Meta-analyses demonstrate copper involvement in Alzheimer's disease (AD), and the systemic ceruloplasmin status in relation to copper is an emerging issue. To deepen this matter, we evaluated levels of ceruloplasmin concentration, ceruloplasmin activity, ceruloplasmin specific activity (eCp/iCp), copper, non-ceruloplasmin copper iron, transferrin, the ceruloplasmin/transferrin ratio, and the APOE genotype in a sample of 84 AD patients and 58 healthy volunteers. From the univariate logistic analyses we found that ceruloplasmin concentration, eCp/iCp, copper, transferrin, the ceruloplasmin/transferrin ratio, and the APOE genotype were significantly associated with the probability of AD. In the multivariable logistic regression analysis, we selected the best subset of biological predictors by the forward stepwise procedure. The analysis showed a decrease of the risk of having AD for eCp/iCp (p = 0.001) and an increase of this risk for non-ceruloplasmin copper (p = 0.008), age (p = 0.001), and APOE-ɛ4 allele (p <  0.001). The estimated model showed a good power in discriminating AD patients from healthy controls (area under curve: 88% ; sensitivity: 66% ; specificity 93%). These data strength the breakdown of copper homeostasis and propose eCp/iCp as a reliable marker of ceruloplasmin status.

Serum Iron, Zinc, and Copper Levels in Patients with Alzheimer's Disease: A Replication Study and Meta-Analyses

To evaluate whether iron, zinc, and copper levels in serum are disarranged in Alzheimer's disease (AD), we performed meta-analyses of all studies on the topic published from 1984 to 2014 and contextually carried out a replication study in serum as well. Our meta-analysis results showed that serum zinc was significantly lower in AD patients. Our replication and meta-analysis results showed that serum copper was significantly higher in AD patients than in healthy controls, so our findings were consistent with the conclusions of four previously published copper meta-analyses. Even if a possible role of iron in the pathophysiology of the disease could not be ruled out, the results of our meta-analysis showed no change of serum iron levels in AD patients, but this conclusion was not robust and requires further investigation. The meta-regression analyses revealed that in some studies, differences in serum iron levels could be due to the different mean ages, while differences in zinc levels appeared to be due to the different sex ratios. However, the effect of sex ratio on serum zinc levels in our meta-analysis is subtle and needs further confirmation. Also, diverse demographic terms and methodological approaches appeared not to explain the high heterogeneity of our copper meta-analysis. Therefore, when investigating trace elements, covariants such as age and sex have to be taken into account in the analyses. In the light of these findings, we suggest that the possible alteration of serum zinc and copper levels are involved in the pathogenesis of AD.

Characterization of biometal profiles in neurological disorders

This review summarizes the findings on dysregulation of metal ions in neurological diseases and tries to develop and predict specific biometal profiles.