Serum Iron, Vitamin B12 and Folic Acid Levels in Parkinson’s Disease

Evolving insights into erythrocytes in synucleinopathies

Synucleinopathies, including Parkinson's disease (PD), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB), are characterized by neuronal loss accompanied by α-synuclein (α-syn) accumulation in the brain. While research conventionally focused on brain pathology, there is growing interest in peripheral alterations. Erythrocytes, which are rich in α-syn, have emerged as a compelling site for synucleinopathies-related alterations. Erythrocyte-derived extracellular vesicles (EVs), containing pathological α-syn species, can traverse the blood-brain barrier (BBB) under certain conditions and the gastrointestinal tract, where α-syn and gut microbiota interact extensively. This review explores the accumulating evidence of erythrocyte involvement in synucleinopathies, as well as their potential in disease pathogenesis and diagnosis. Given their unique properties, erythrocytes and erythrocyte-derived EVs may also serve as an ideal therapeutic platform for treating synucleinopathies and beyond.

Evidence for genetic causality between iron homeostasis and Parkinson's disease: A two-sample Mendelian randomization study

BACKGROUND

Parkinson's disease (PD) is a degenerative disease of the central nervous system, and its specific etiology is still unclear. At present, it is believed that the main pathological basis is the reduction of dopamine concentration in the brain striatum. Although many previous studies have believed that iron as an important nutrient element participates in the occurrence and development of PD, whether there is a causal correlation between total iron binding capacity(TIBC), transferring saturation(TSAT), ferritin and serum iron in iron homeostasis indicators and PD, there has been a lack of effective genetic evidence.

METHODS

We used Mendelian randomization (MR) as an analytical method to effectively evaluate the genetic association between exposure and outcome, based on the largest genome-wide association study (GWAS) data to date. By using randomly assigned genetic instrumental variables (SNPs, Single Nucleotide Polymorphisms) that are not affected by any causal relationship, we effectively evaluated the causal relationship between iron homeostasis indicators and PD while controlling for confounding factors.

RESULTS

By coordinated analysis of 86 SNPs associated with iron homeostasis markers and 12,858,066 SNPs associated with PD, a total of 56 SNPs were finally screened for genome-wide significance of iron homeostasis associated with PD. The results of inverse variance weighting(IVW) analysis suggested that iron（ β = - 0.524; 95%cl=-0.046 to -0.002; P=0.032) was considered to have a genetic causal relationship with PD. Cochran's Q, Egger intercept and MR-PRESSO global tests did not detect the existence of heterogeneity and pleiotropy (P>0.05). Mr Steiger directionality test further confirmed our estimation of the potential causal direction of iron and PD (P=0.001). In addition, TIBC (β=-0.142; 95%Cl=-0.197-0.481; P=0.414), TSAT (β=-0.316; 95%Cl=-0.861-0.229; P=0.255), and ferritin (β=-0.387; 95%Cl=-1.179-0.405; P=0.338) did not have genetic causal relationships with PD, and the results were not heterogeneous and pleiotropic (P>0.05). In addition, TIBC (β=-0.142; 95%Cl=-0.197-0.481; P=0.414), TSAT (β=-0.316; 95%Cl=-0.861-0.229; P=0.255), and ferritin (β=-0.101; 95%Cl=--0.987 to -0.405; P=0.823) did not have genetic causal relationships with PD, and the results were not heterogeneous and pleiotropic (P>0.05). TIBC (P=0.008), TSAT (P=0.000) and ferritin (P=0.013) were all consistent with the estimation of MR Steiger directivity test.

CONCLUSION

Our study found that among the four iron homeostasis markers, there was a genetic causal association between serum iron and PD, and the serum iron level was negatively correlated with the risk of PD. In addition, TIBC, TSAT, ferritin had no genetic causal relationship with PD.

Association between serum potassium and Parkinson's disease in the US (NHANES 2005-2020)

Background

Evaluating the correlation between serum potassium and Parkinson's disease (PD) in US adults.

Methods

A cross-sectional study was conducted on 20,495 adults aged 40 years or older using NHANES data from 2005 to 2020. The study utilized one-way logistic regression and multifactorial logistic regression to examine the correlation between serum potassium levels and PD. Additionally, a smoothed curve fitting approach was employed to assess the concentration-response relationship between serum potassium and PD. Stratified analyses were carried out to investigate potential interactions between serum potassium levels and PD with variables such as age, sex, race, marital status, education, BMI, smoking and medical conditions like coronary, stroke, diabetes, hypertension, and hypercholesterolemia.

Results

In this study, a total of 20,495 participants, comprising 403 PD and 20,092 non-PD individuals, were included. After adjusted for covariates, multivariable logistic regression revealed that high serum potassium level was an independent risk factor for PD (OR:1.86, 95% CI:1.45 ~ 2.39, p < 0.01).The linear association between serum potassium and PD was described using fitted smoothing curves. Age, sex, race, education, marital, BMI, coronary, stroke, diabetes, hypertension and hypercholesterolemia were not significantly correlated with this positive connection, according to subgroup analysis and interaction testing (P for interaction >0.05).

Conclusion

Serum potassium levels are elevated in patients with Parkinson's disease compared to non-PD patients. Additional prospective studies are required to explore the significance of serum potassium levels in individuals with Parkinson's disease.

Metal Exposure and Risk of Parkinson Disease: A Systematic Review and Meta-Analysis

Metal exposure has been suggested as a possible environmental risk factor for Parkinson disease (PD). We searched the PubMed, EMBASE, and Cochrane databases to systematically review the literature on the relationship between metal exposure and PD risk and to examine the overall quality of each study and the exposure assessment method. A total of 83 case-control studies and 5 cohort studies published during the period 1963-July 2021 were included, of which 73 were graded as being of low or moderate overall quality. Investigators in 69 studies adopted self-reported exposure and biomonitoring after disease diagnosis for exposure assessment approaches. The meta-analyses showed that concentrations of copper and iron in serum and concentrations of zinc in either serum or plasma were lower, while concentrations of magnesium in CSF and zinc in hair were higher, among PD cases as compared with controls. Cumulative lead levels in bone were found to be associated with increased risk of PD. We did not find associations between other metals and PD. The current level of evidence for associations between metals and PD risk is limited, as biases from methodological limitations cannot be ruled out. High-quality studies assessing metal levels before disease onset are needed to improve our understanding of the role of metals in the etiology of PD.

Association of women-specific health factors in the severity of Parkinson's disease

Parkinson's disease (PD) is an age-related neurological disorder known for the observational differences in its risk, progression, and severity between men and women. While estrogen has been considered to be a protective factor in the development of PD, there is little known about the role that fluctuations in hormones and immune responses from sex-specific health experiences have in the disease's development and severity. We sought to identify women-specific health experiences associated with PD severity, after adjusting for known PD factors, by developing and distributing a women-specific questionnaire across the United States and creating multivariable models for PD severity. We created a questionnaire that addresses women's specific experiences and their PD clinical history and deployed it through The Parkinson's Foundation: PD Generation. To determine the association between women-specific health factors and PD severity, we constructed multivariable logistic regression models based on the MDS-UPDRS scale and the participants' questionnaire responses, genetics, and clinical data. For our initial launch in November 2021, we had 304 complete responses from PD GENEration. Univariate and multivariate logistic modeling found significant associations between major depressive disorder, perinatal depression, natural childbirth, LRRK2 genotype, B12 deficiency, total hysterectomy, and increased PD severity. This study is a nationally available questionnaire for women's health and PD. It shifts the paradigm in understanding PD etiology and acknowledging how sex-specific experiences may contribute to PD severity. In addition, the work in this study sets the foundation for future research to investigate the factors behind sex differences in PD.

Intraperitoneal injection of iron dextran induces peripheral iron overload and mild neurodegeneration in the nigrostriatal system in C57BL/6 mice

AIMS

Elevated iron levels in the affected areas of brain are linked to several neurodegenerative diseases including Parkinson's disease (PD). This study investigated the influence of peripheral iron overload in peripheral tissues, as well as its entry into the brain regions on lysosomal functions. The survival of dopaminergic neurons in the nigrostriatal system and motor coordination were also investigated.

MAIN METHODS

An intraperitoneal injection of iron dextran (FeDx) mouse model was established. Western blot was used to detect iron deposition and lysosomal functions in the liver, spleen, hippocampal (HC), striatum (STR), substantia nigra (SN) and olfactory bulb (OB). Iron in serum and cerebrospinal fluid (CSF) was determined by an iron assay kit. Immunofluorescence and immunohistochemical staining were applied to detect dopaminergic neurons and fibers. Motor behavior was evaluated by gait analysis.

KEY FINDINGS

Iron was deposited consistently in the liver and spleen, and serum iron was elevated. While iron deposition occurred late in the HC, STR and SN, without apparently affecting CSF iron levels. Although cathepsin B (CTSB), cathepsin D (CTSD), glucocerebrosidase (GCase) and lysosome integrated membrane protein 2 (LIMP-2) protein levels were dramatically up-regulated in the liver and spleen, they were almost unchanged in the brain regions. However, CTSB was up-regulated in acute iron-overloaded OB and primary cultured astrocytes. The number of dopaminergic neurons in the SN remained unchanged, and mice did not exhibit significant motor incoordination.

SIGNIFICANCE

Intraperitoneal injection of FeDx in mice induces largely peripheral iron overload while not necessarily sufficient to cause severe disruption of the nigrostriatal system.

Vitamin B12 Ameliorates the Pathological Phenotypes of Multiple Parkinson's Disease Models by Alleviating Oxidative Stress

Parkinson's disease (PD) is the second most common neurodegenerative disease characterized by progressive loss of dopaminergic neurons in the substantia nigra of the midbrain. The etiology of PD has yet to be elucidated, and the disease remains incurable. Increasing evidence suggests that oxidative stress is the key causative factor of PD. Due to their capacity to alleviate oxidative stress, antioxidants hold great potential for the treatment of PD. Vitamins are essential organic substances for maintaining the life of organisms. Vitamin deficiency is implicated in the pathogenesis of various diseases, such as PD. In the present study, we investigated whether administration of vitamin B12 (VB12) could ameliorate PD phenotypes in vitro and in vivo. Our results showed that VB12 significantly reduced the generation of reactive oxygen species (ROS) in the rotenone-induced SH-SY5Y cellular PD model. In a Parkin gene knockout C. elegans PD model, VB12 mitigated motor dysfunction. Moreover, in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse PD model, VB12 also displayed protective effects, including the rescue of mitochondrial function, dopaminergic neuron loss, and movement disorder. In summary, our results suggest that vitamin supplementation may be a novel method for the intervention of PD, which is safer and more feasible than chemical drug treatment.

Ginsenoside Rg1 Plays a Neuroprotective Role in Regulating the Iron-Regulated Proteins and Against Lipid Peroxidation in Oligodendrocytes

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Progressive loss of dopaminergic neurons in the substantia nigra (SN) is one of the major pathological changes. However, the reasons for the dopaminergic neuron loss are still ambiguous and further studies are needed to evaluate the in-depth mechanisms of neuron death. Oxidative stress is a significant factor causing neuronal damage. Dopaminergic neurons in the SN are susceptible to oxidative stress, which is closely associated with iron dyshomeostasis in the brain. Ginsenoside Rg1 from ginseng plays a crucial role in neuroprotective effects through anti-inflammation and attenuating the aggregation of abnormal α-synuclein. In our study, we established a chronic PD mouse model by 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine combined with probenecid and explored the effect of Rg1 on the oxidative stress and brain iron homeostasis. Rg1 was verified to improve the level of tyrosine hydroxylase and anti-oxidant stress. In addition, Rg1 maintained the iron-regulated protein homeostasis by increasing the expression of ferritin heavy chain and decreasing ferritin light chain in oligodendrocytes, especially the mature oligodendrocytes (OLs). Furthermore, Rg1 had a positive effect on the myelin sheath protection and increased the number of mature oligodendrocytes, proved by the increased staining of myelin basic protein and CC-1. In conclusion, Rg1 could play a neuroprotective role through remitting the iron-regulated protein dyshomeostasis by ferritin and against lipid peroxidation stress in oligodendrocytes.

Elevated Heme Oxygenase-1 Correlates With Increased Brain Iron Deposition Measured by Quantitative Susceptibility Mapping and Decreased Hemoglobin in Patients With Parkinson's Disease

Background: Brain iron deposition, low hemoglobin (HGB), and increased heme oxygenase-1 (HO-1) have been implicated in Parkinson’s disease (PD). However, the association among them in PD is poorly studied.

Objective: To explore the association of the level of HO-1 with brain iron deposition and low level of HGB in PD.

Methods: A total of 32 patients with PD and 26 controls were recruited for this study. C57BL/6 male mice were used in generating 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced chronic PD model. The Levels of serum HO-1 and HGB of human subjects and mice were assayed by ELISA, blood routine test, respectively. Quantitative susceptibility mapping (QSM) was used to quantitatively analyze brain iron deposition in human subjects and mice. HO-1 inhibitor (Sn-protoporphyrin, SnPP) was used to suppress the function and expression of HO-1 in PD mice. Correlations between the concentration of serum HO-1 and iron deposition of the region of interests (ROIs), levels of HGB, between the three factors mentioned above, and scores of clinical scales were explored in PD patients.

Results: This study revealed significant elevation of the serum HO-1 concentration, iron deposition within bilateral substantial nigra (SN), red nucleus (RN), and putamen (PUT) and decrease of HGB level in PD patients. There was a significantly positive correlation between the serum HO-1 concentration and iron deposition within SN, an inverse correlation between the serum HO-1 concentration and HGB level in PD patients. A significant increase in HO-1 expression of serum and iron deposition in SN was also observed in the PD mouse model, and the SnPP could significantly reduce iron deposition in the SN.

Conclusions: The high level of HO-1 may be the common mechanism of iron deposition and low HGB in PD. Therefore, the findings presented in this study indicate that HO-1 correlates with brain iron deposition and anemia in PD.

Iron Status May Not Affect Amyotrophic Lateral Sclerosis: A Mendelian Randomization Study

Background

Observational studies have shown an association of increased iron status with a higher risk of amyotrophic lateral sclerosis (ALS). Iron status might be a novel target for ALS prevention if a causal relationship exists. We aimed to reveal the causality between iron status and ALS incidence using a large two-sample Mendelian randomization (MR).

Methods

Single nucleotide polymorphisms (SNPs) for iron status were identified from a genome-wide association study (GWAS) on 48,972 individuals. The outcome data came from the largest ALS GWAS to date (20,806 cases; 59,804 controls). We conducted conservative analyses (using SNPs with concordant change of biomarkers of iron status) and liberal analyses (using SNPs associated with at least one of the biomarkers of iron status), with inverse variance weighted (IVW) method as the main analysis. We then performed sensitivity analyses including weighted median, MR-Egger and MR-pleiotropy residual sum and outlier, as well as leave-one-out analysis to detect pleiotropy.

Results

In the conservative analyses, we found no evidence of association between four biomarkers of iron status and ALS using IVW method with odds ratio (OR) 1.00 [95% confidence interval (CI): 0.90-1.11] per standard deviation (SD) increase in iron, 0.96 (95% CI: 0.77-1.21) in ferritin, 0.99 (95% CI: 0.92-1.07) in transferrin saturation, and 1.04 (95% CI: 0.93-1.16) in transferrin. Findings from liberal analyses were similar, and sensitivity analyses suggested no pleiotropy detected (all p > 0.05).

Conclusion

Our findings suggest no causal effect between iron status and risk of ALS. Efforts to change the iron status to decrease ALS incidence might be impractical.

Study on different pathogenic factors in different disease stages of patients with Wilson disease

OBJECTIVE

To investigate in different stages of patients with Wilson disease (WD), there are different pathogenic factors such as metal deposition, oxidative stress, and inflammatory response in the brain.

METHODS

A total of 32 untreated WD patients and 10 normal controls were enrolled in the study. The neurological symptoms were evaluated using the modified Young scale. Liver function, metal metabolism, susceptibility-weighted imaging (SWI), diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS) examination were done. The clinical disease stages were divided into metal deposition period, fiber damage period, and neuronal necrosis period according to the imaging results. The content of 24-h urine copper, serum copper, and serum iron; and the levels of catalase (CAT), glutathione peroxidase (GSH-PX), malondialdehyde (MDA), nitric oxide (NO), nitric oxide synthase (NOS), superoxide dismutase (SOD), interleukin (IL-1), and tumor necrosis factor alpha (TNF-α) were detected.

RESULTS

The contents of urinary copper in WD patients at neuronal necrosis stage were lower than those in patients at the metal deposition stage (P = 0.011) and fiber injury stage (P = 0.023). The contents of NOS (P = 0.039) and NO (P = 0.047) in WD patients at the stage of fiber injury were higher than those of the normal control, while GSH-PX (P = 0.025) and CAT (P = 0.041) were lower in the neuronal necrosis stage. In the stage of neuronal necrosis, the levels of IL-1 (P = 0.030) and TNF-α were higher than those of the normal control (P = 0.042). The neurological symptom scores in patients with fiber injury (P = 0.013) and neuron injury were higher than those with metal deposition (P = 0.026).

CONCLUSION

There are different pathogenic factors in different stages of WD. At the neuronal necrosis stage, copper deposition was decreased in WD patients. In the stage of fiber injury and neuronal necrosis, there is oxidative stress injury in WD patients. In the neuronal necrosis phase, WD patients have an inflammatory response.

Iron Dysregulation and Inflammagens Related to Oral and Gut Health Are Central to the Development of Parkinson's Disease

Neuronal lesions in Parkinson's disease (PD) are commonly associated with α-synuclein (α-Syn)-induced cell damage that are present both in the central and peripheral nervous systems of patients, with the enteric nervous system also being especially vulnerable. Here, we bring together evidence that the development and presence of PD depends on specific sets of interlinking factors that include neuroinflammation, systemic inflammation, α-Syn-induced cell damage, vascular dysfunction, iron dysregulation, and gut and periodontal dysbiosis. We argue that there is significant evidence that bacterial inflammagens fuel this systemic inflammation, and might be central to the development of PD. We also discuss the processes whereby bacterial inflammagens may be involved in causing nucleation of proteins, including of α-Syn. Lastly, we review evidence that iron chelation, pre-and probiotics, as well as antibiotics and faecal transplant treatment might be valuable treatments in PD. A most important consideration, however, is that these therapeutic options need to be validated and tested in randomized controlled clinical trials. However, targeting underlying mechanisms of PD, including gut dysbiosis and iron toxicity, have potentially opened up possibilities of a wide variety of novel treatments, which may relieve the characteristic motor and nonmotor deficits of PD, and may even slow the progression and/or accompanying gut-related conditions of the disease.

Principal component analysis of routine blood test results with Parkinson's disease: A case-control study

This study aimed to explore the association of routine blood test values and blood cell ratios with the risk or severity of Parkinson's disease (PD). The medical records of 453 PD patients and 436 controls were retrospectively reviewed. The severity of PD was quantified by the modified Hoehn-Yahr (HY) scale. We performed principal component analysis (PCA) of significant values/ratios and used logistic regression analysis to explore the relationship between principal components (PCs) and the risk of PD. Spearman correlation and ordinal logistic regression analyses were performed to explore the relationship between indicators and the severity of PD. The PCA generated 9 PCs, which contributed to 90.86% of the total variance. Logistic regression analysis revealed positive associations of PC2 (a measure monocyte ratios) and PC6 (a measure of platelet ratios and volume) and negative associations of PC1 (a comprehensive measure of lymphocyte, eosinophil, neutrophil, and red blood cell values), PC4 (a measure of red blood cell values), and PC7 (a measure of red blood cell values and platelet volume) with the risk of PD. However, we observed no associations of variables with the severity of PD. In conclusion, PCA reduced the dimensionality of the data. Peripheral blood disorders may be associated with PD.

Biological fluid levels of iron and iron-related proteins in Parkinson's disease: Review and meta-analysis

BACKGROUND AND PURPOSE

Several studies suggested a role or iron in the pathogenesis or Parkinson's disease (PD), and substantia nigra iron concentrarions have been found increased in PD. However, the results on cerebrospinal (CSF) and serum/plasma iron levels in PD patients have been controversial. The aim of this systematic review and meta-analysis was to establish the CSF and serum/plasma levels of iron and iron-related proteins (ferritin, transferrin, lactoferrin, haptoglobin, and hepcidine) levels, and the urine levels of iron, in patients with PD.

METHODS

Four databases (PubMed, EMBASE, MedLine, and Web of Science - Core Collection) were reviewed for studies published from 1966 to October 5, 2020. References of interest were identified. A meta-analysis of eligible studies was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines, using the R software package meta.

RESULTS

A non-significant trend towards higher CSF iron levels and marginally significantly lower serum/plasma iron levels was observed in patients with PD compared with age- and sex-matched controls. CSF and serum/plasma ferritin and transferrin concentrations, and serum/plasma lactoferrin and haptoglobin concentrations did not differ significantly between PD patients and controls.

CONCLUSION

The findings of this study suggest an association between decreased serum/plasma iron levels and, possibly, higher CSF iron levels with risk of PD.

Shared perturbations in the metallome and metabolome of Alzheimer's, Parkinson's, Huntington's, and dementia with Lewy bodies: A systematic review

Despite differences in presentation, age-related dementing diseases such as Alzheimer's (AD), Parkinson's (PD), and Huntington's diseases (HD), and dementia with Lewy bodies (DLB) may share pathogenic processes. This review aims to systematically assemble and compare findings in various biochemical pathways across these four dementias. PubMed and Google Scholar were screened for articles reporting on brain and biofluid measurements of metals and/or metabolites in AD, PD, HD, or DLB. Articles were assessed using specific a priori-defined inclusion and exclusion criteria. Of 284 papers identified, 198 met criteria for inclusion. Although varying coverage levels of metals and metabolites across diseases and tissues made comparison of many analytes impossible, several common findings were identified: elevated glucose in both brain tissue and biofluids of AD, PD, and HD cases; increased iron and decreased copper in AD, PD and HD brain tissue; and decreased uric acid in biofluids of AD and PD cases. Other analytes were found to differ between diseases or were otherwise not covered across all conditions. These findings indicate that disturbances in glucose and purine pathways may be common to AD, PD, and HD. However, standardisation of methodologies and better coverage in some areas - notably of DLB - are necessary to validate and extend these findings.

Iron and inflammation: in vivo and post-mortem studies in Parkinson's disease

In these present studies, in vivo and and post-mortem studies have investigated the association between iron and inflammation. Early-stage Parkinson's disease (PD) patients, of less than 5 years disease duration, showed associations of plasmatic ferritin concentrations with both proinflammatory cytokine interleukin-6 and hepcidin, a regulator of iron metabolism as well as clinical measures. In addition ratios of plasmatic ferritin and iron accumulation in deep grey matter nuclei assessed with relaxometry T2* inversely correlated with disease severity and duration of PD. On the hand, post-mortem material of the substantia nigra compacta (SNc) divided according to Braak and Braak scores, III-IV and V-VI staging, exhibited comparable microgliosis, with a variety of phenotypes present. There was an association between the intensity of microgliosis and iron accumulation as assayed by Perl's staining in the SNc sections. In conclusion, markers of inflammation and iron metabolism in both systemic and brain systems are closely linked in PD, thus offering a potential biomarker for progression of the disease.

Nutritional Status Associated with Molecular Biomarkers, Physiological Indices, and Clinical Severity in Parkinson's Disease Patients

This study is intended to explore the associations between nutritional status and molecular biomarkers and the clinical severity of Parkinson's disease (PD), as well as to examine the differences in related factors between PD patients with normal nutrition and those with at risk for malnutrition. A cross-sectional assessment of 82 consecutive outpatients with PD was conducted using the mini nutritional assessment (MNA), Unified Parkinson's Disease Rating Scale (UPDRS), and the Hoehn and Yahr scale to determine the nutritional status, the clinical severity of PD, and the stage of the disease. Recordings of blood samples collected after 12 h of overnight fasting were also assessed in terms of serum levels of glycated hemoglobin (HbA1c), blood urea nitrogen (BUN), creatinine, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), hemoglobin (Hgb), folate, and vitamin B12. All participants were divided into normal nutrition and malnutrition risk groups via the MNA scores to compare the above-mentioned parameters. The results showed that the total MNA score was significantly correlated with some parts of the UPDRS scale (e.g., Sections 1 and 2) and the levels of HbAlc in PD patients and those with risk for malnutrition, with significantly lower weight and body mass index (BMI), and with lower levels of Hgb and HDL. Higher levels of cholesterol were observed in the malnutrition risk group as compared with the normal nutrition group. The findings suggest that the clinical severity of PD is associated with nutritional status. Body weight, BMI, and the levels of Hgb, cholesterol, and HDL could be, at least partially, important biological markers to monitor malnutrition and the progression of the disease.

Serum B12, Homocysteine Levels, and their Effect on Peripheral Neuropathy in Parkinson's Disease: Indian Cohort

Background:

Cobalamin deficiency, either due to dietary inadequacy or increased consumption attributable to levodopa-mediated metabolic disturbance, and resultant hyperhomocysteinemia may contribute to peripheral neuropathy (PN) in Parkinson's disease (PD).

Aim:

The aim of the study is to assess the prevalence of Vitamin B12 deficiency, hyperhomocysteinemia in Indian PD patients, and their association with PN.

Materials and Methods:

Clinical details were collected in 93 patients over a period of 2 years. Seventy controls were included in the study. Serum B12, homocysteine, folate, electroneurography, and autonomic function tests were done. The prevalence of B12 deficiency and hyperhomocysteinemia in PD patients and controls was assessed. The association of B12 and homocysteine levels with patients’ age, disease duration, levodopa equivalent daily dose, cumulative levodopa dose, Unified Parkinson's Disease Rating Scale-III off score, modified Hoehn and Yahr score, and presence or absence of PN was studied.

Results:

Serum B12, homocysteine levels, prevalence of B12 deficiency, and hyperhomocysteinemia were no different between cases and controls. Seven of 93 (9.68%) PD patients had PN. The median values of serum B12, folate, and homocysteine levels across patients with or without PN could not be compared as only seven of our patients had PN.

Conclusion:

The prevalence of B12 deficiency, hyperhomocysteinemia, and incidence of PN among our patients is very less when compared to the Western population. The conjecture that PN in PD patients may be secondary to B12 deficiency/hyperhomocysteinemia stands as a speculation.

Cell Ratio Differences in Peripheral Blood between Early- and Late-Onset Parkinson's Disease: A Case-Control Study

Objectives

To explore the differences of immune disorders in peripheral blood between patients with early-onset Parkinson's disease (EOPD) and late-onset Parkinson's disease (LOPD).

Methods

We retrospectively reviewed medical records of Parkinson's disease (PD) patients and healthy controls between June 2002 and July 2017. At last, we included 117 PD patients who were divided into EOPD and LOPD according to whether onset age of PD was after 50 and 99 controls divided into E-Control (match for EOPD) and L-Control (match for LOPD) according to whether their age was after 53 which was onset age plus median of disease duration. We compared the ratios of cells between multiple groups and performed the multinominal logistic regression analysis to explore the relationship between ratios and subtypes of PD. We also carried out the receiver operating characteristic (ROC) curve analysis to estimate the diagnostic value of the variable.

Results

Lymphocyte-red blood cell ratio (LRR) was lower in LOPD compared with that in EOPD or L-Control. LRR was also negatively associated with LOPD (OR: 0.623; 95% CI: 0.397–0.980; P=0.040). The ROC curve analysis showed the optimal cutoff value of 4.53 (×10⁻⁴) of LRR for discrimination of LOPD versus L-Control (sensitivity: 0.596, specificity: 0.764). The area under curve (AUC) was 0.721. As for LOPD versus EOPD, the optimal threshold of LRR was 4.10 (×10⁻⁴) (sensitivity: 0.516, specificity: 0.745). AUC was 0.641.

Conclusions

Peripheral immune disorders might play an important part in the pathological progression of LOPD. Also, LRR has potential diagnostic value.

Iron Concentration Does Not Differ in Blood but Tends to Decrease in Cerebrospinal Fluid in Parkinson's Disease

Background

Iron accumulation in the substantia nigra in PD patients was acknowledged, but the studies on alteration of iron levels in blood and cerebrospinal fluids (CSF) reported inconsistent results.

Objective

To determinate the alterations of blood and CSF levels of iron in PD patients, a case-control study and a meta-analysis both in blood and CSF were conducted.

Methods

In the case-control study, 43 PD patients and 33 controls were recruited to test iron metabolism, 15 normal and 12 PD patients donated CSF. Levels in iron were quantified by inductively coupled atomic emission spectrometry. Iron metabolism was analyzed by routine blood tests. In the meta-analysis, a comprehensive literature search was performed on relevant studies published from Jan 1980 to Dec 2018 in PubMed, Web of Science and EMBASE databases. The pooled standard mean difference (SMD) with random effects model was selected to estimate the association between iron levels and PD.

Results

In the case-control study, the iron level in serum in the controls and PD patients were 110.00 ± 48.75 μg/dl and 107.21 ± 34.25 μg/dl, respectively, no significant difference was found between them (p = 0.850), with a small effect size (Cohen’s d: 0.12; 95% CI: 0.08–0.17). Ferritin level in PD patients was lower than controls (p = 0.014). The CSF levels of iron in control and the PD patients were 20.14 ± 3.35 ng/dl and 16.26 ± 4.82 ng/dl, respectively. CSF levels of iron were lower in PD compared with that of controls (p = 0.021), with a moderate effect size (Cohen’s d: 0.51; 95% CI: 0.43–0.65). In the meta-analysis, 22 eligible studies and a total of 3607 participants were identified. Blood levels of iron did not differ significant between PD patients and the controls [SMD (95% CI): −0.03 (−0.30, 0.24)], but CSF iron levels tended to be lower in PD patients compared with that in the controls [SMD (95% CI): −0.33 (−0.65, −0.00)].

Conclusion

Iron homeostasis may be disturbed in CSF, but not in the peripheral blood in PD.

Tremor-Dominant in Parkinson Disease: The Relevance to Iron Metabolism and Inflammation

Background: Tremor is one of the most predominant symptoms of patients with Parkinson disease (PD), but the underlying mechanisms for tremor relating to iron and its metabolism-related proteins and the inflammatory factors in cerebrospinal fluid (CSF) and serum have not been fully elucidated. Methods: A total of 135 PD patients were divided into a tremor-dominant (PD-TD) group (N = 74) and a postural instability and gait difficulty-dominant (PD-PIGD) group (N = 39) based on the ratio of mean tremor score to the mean bradykinesia/rigid score of the Unified Parkinson's Disease Rating Scale (UPDRS) III. Age and sex-matched healthy controls were recruited (N = 35). Demographic variables were evaluated; iron and its metabolism-related proteins and the inflammatory mediators in both CSF and serum were measured in these groups. The relevance of iron metabolism, inflammation and PD-TD were analyzed. Results: (1) The PD-TD group had significantly decreased L-ferritin, increased iron levels in CSF and increased ferritin levels in the serum compared with the PD-PIGD and control groups (P < 0.05). (2) The PD-TD group had significantly enhanced IL-6 levels in both CSF and serum compared with the PD-PIGD and control groups (P < 0.05). (3) In CSF, the IL-6 level was increased as the iron level was elevated in the PD-TD group (r = 0.308, P = 0.022). In serum, the IL-6 level was increased as the ferritin level was elevated in the PD-TD group (r = 0.410, P = 0.004). Conclusion: The interplay between disturbed iron metabolism and relevant inflammation might modulate clinical phenotypes of PD.

Biological and Clinical Implications of Comorbidities in Parkinson's Disease

A wide spectrum of comorbidities has been associated with Parkinson's disease (PD), a progressive neurodegenerative disease that affects more than seven million people worldwide. Emerging evidence indicates that chronic diseases including diabetes, depression, anemia and cancer may be implicated in the pathogenesis and progression of PD. Recent epidemiological studies suggest that some of these comorbidities may increase the risk of PD and precede the onset of motor symptoms. Further, drugs to treat diabetes and cancer have elicited neuroprotective effects in PD models. Nonetheless, the mechanisms underlying the occurrence of these comorbidities remain elusive. Herein, we discuss the biological and clinical implications of comorbidities in the pathogenesis, progression, and clinical management, with an emphasis on personalized medicine applications for PD.

Intake of vitamin B before onset of Parkinson's disease and atypical parkinsonism and olfactory function at the time of diagnosis

BACKGROUND/OBJECTIVES

To investigate whether vitamin-B density in the diet 2-8 years before diagnosis is associated with olfactory function at the time of diagnosis.

SUBJECTS/METHODS

This prospective nested case-control study included patients with Parkinson's disease (PD), multiple system atrophy and progressive supranuclear paralysis identified between 2004 and 2009 in the county of Västerbotten in northern Sweden. The case database (NYPUM study; Newly Diagnosed Parkinson in Umeå; n=147) was cross-linked to the Northern Sweden Health and Disease Study (NSHDS). Identified patients (n=96) and controls (n=375) were matched for sex, age, year of health survey, sub-cohort and geographical area. Dietary intake was assessed by a food frequency questionnaire, and the brief smell identification test (B-SIT) was used to measure olfactory function at the time of diagnosis.

RESULTS

There was no difference in vitamin-B or any other macro- or micro-nutrient densities, energy intake or body mass index (kg/m²; BMI) between patients and controls at baseline at the time of the healthcare survey. A lower thiamin and folate density, amount per 1 megajoule, was reported in patients who scored below median on B-SIT (<7) when compared with that in patients who scored ⩾7 at the time of diagnosis. After adjusting for age, sex and BMI using linear and logistic regressions, an even stronger association was found between thiamin density and olfactory function.

CONCLUSIONS

A low thiamin and folate density in the reported diet, 2-8 years before PD diagnosis, was significantly associated with olfactory dysfunction at the time of PD diagnosis.

Meta-analysis of the association between serum iron levels and Parkinson's disease: Evidence from 11 publications

BACKGROUND

There is no consensus on the serum iron levels and Parkinson's disease (PD). The aim of this study is to conduct a systematic review and meta-analysis to analyse the relationship between serum iron levels and PD risk.

METHODS

We searched the databases of PubMed, Web of knowledge, Embase, the Cochrane Library, China National Knowledge Infrastructure (CNKI) and China Biology Medical literature to assess the association between serum iron levels and PD risk. Standardized mean differences (SMD) and 95% confidence intervals (CI) with random-effect model were used to combine the results.

RESULTS

Eleven related articles met our selection criteria and contained a total of 829PD patients and 1219 healthy controls. Our meta-analysis results revealed that the serum iron levels in PD patients were significantly higher than those in healthy controls (SMD=0.27, 95% CI=0.18, 0.37, P<0.001). Subgroup analysis by ethnicity showed that the serum iron levels in PD patients were significantly higher than controls both in Asian populations and European populations. Significant associations were also found in prospective studies and case-control studies.

CONCLUSIONS

Our meta-analysis showed strong evidence that a significantly higher serum iron levels are present in PD patients when compared to the healthy controls.

COPPADIS-2015 (COhort of Patients with PArkinson's DIsease in Spain, 2015), a global--clinical evaluations, serum biomarkers, genetic studies and neuroimaging--prospective, multicenter, non-interventional, long-term study on Parkinson's disease progression

Background

Parkinson’s disease (PD) is a progressive neurodegenerative disorder causing motor and non-motor symptoms that can affect independence, social adjustment and the quality of life (QoL) of both patients and caregivers. Studies designed to find diagnostic and/or progression biomarkers of PD are needed. We describe here the study protocol of COPPADIS-2015 (COhort of Patients with PArkinson’s DIsease in Spain, 2015), an integral PD project based on four aspects/concepts: 1) PD as a global disease (motor and non-motor symptoms); 2) QoL and caregiver issues; 3) Biomarkers; 4) Disease progression.

Methods/design

Observational, descriptive, non-interventional, 5-year follow-up, national (Spain), multicenter (45 centers from 15 autonomous communities), evaluation study. Specific goals: (1) detailed study (clinical evaluations, serum biomarkers, genetic studies and neuroimaging) of a population of PD patients from different areas of Spain, (2) comparison with a control group and (3) follow-up for 5 years. COPPADIS-2015 has been specifically designed to assess 17 proposed objectives. Study population: approximately 800 non-dementia PD patients, 600 principal caregivers and 400 control subjects. Study evaluations: (1) baseline includes motor assessment (e.g., Unified Parkinson’s Disease Rating Scale part III), non-motor symptoms (e.g., Non-Motor Symptoms Scale), cognition (e.g., Parkinson’s Disease Cognitive Rating Scale), mood and neuropsychiatric symptoms (e.g., Neuropsychiatric Inventory), disability, QoL (e.g., 39-item Parkinson’s disease Quality of Life Questionnaire Summary-Index) and caregiver status (e.g., Zarit Caregiver Burden Inventory); (2) follow-up includes annual (patients) or biannual (caregivers and controls) evaluations. Serum biomarkers (S-100b protein, TNF-α, IL-1, IL-2, IL-6, vitamin B12, methylmalonic acid, homocysteine, uric acid, C-reactive protein, ferritin, iron) and brain MRI (volumetry, tractography and MTAi [Medial Temporal Atrophy Index]), at baseline and at the end of follow-up, and genetic studies (DNA and RNA) at baseline will be performed in a subgroup of subjects (300 PD patients and 100 control subjects). Study periods: (1) recruitment period, from November, 2015 to February, 2017 (basal assessment); (2) follow-up period, 5 years; (3) closing date of clinical follow-up, May, 2022. Funding: Public/Private.

Discussion

COPPADIS-2015 is a challenging initiative. This project will provide important information on the natural history of PD and the value of various biomarkers.

Iron and Oxidative Stress in Parkinson's Disease: An Observational Study of Injury Biomarkers

Parkinson's disease (PD) is characterized by progressive motor impairment attributed to progressive loss of dopaminergic neurons in the substantia nigra (SN) pars compacta. In addition to an accumulation of iron, there is also an increased production of reactive oxygen/nitrogen species (ROS/RNS) and inflammatory markers. These observations suggest that iron dyshomeostasis may be playing a key role in neurodegeneration. However, the mechanisms underlying this metal-associated oxidative stress and neuronal damage have not been fully elucidated. To determine peripheral levels of iron, ferritin, and transferrin in PD patients and its possible relation with oxidative/nitrosative parameters, whilst attempting to identify a profile of peripheral biomarkers in this neurological condition. Forty PD patients and 46 controls were recruited to compare serum levels of iron, ferritin, transferrin, oxidative stress markers (superoxide dismutase (SOD), catalase (CAT), nitrosative stress marker (NOx), thiobarbituric acid reactive substances (TBARS), non-protein thiols (NPSH), advanced oxidation protein products (AOPP), ferric reducing ability of plasma (FRAP) and vitamin C) as well as inflammatory markers (NTPDases, ecto-5’-nucleotidase, adenosine deaminase (ADA), ischemic-modified albumin (IMA) and myeloperoxidase). Iron levels were lower in PD patients, whereas there was no difference in ferritin and transferrin. Oxidative stress (TBARS and AOPP) and inflammatory markers (NTPDases, IMA, and myeloperoxidase) were significantly higher in PD, while antioxidants FRAP, vitamin C, and non-protein thiols were significantly lower in PD. The enzymes SOD, CAT, and ecto-5’-nucleotidase were not different among the groups, although NOx and ADA levels were significantly higher in the controls. Our data corroborate the idea that ROS/RNS production and neuroinflammation may dysregulate iron homeostasis and collaborate to reduce the periphery levels of this ion, contributing to alterations observed in the pathophysiology of PD.

Parkinson's disease between internal medicine and neurology

General medical problems and complications have a major impact on the quality of life in all stages of Parkinson's disease. To introduce an effective treatment, a comprehensive analysis of the various clinical symptoms must be undertaken. One must distinguish between (1) diseases which arise independently of Parkinson's disease, and (2) diseases which are a direct or indirect consequence of Parkinson's disease. Medical comorbidity may induce additional limitations to physical strength and coping strategies, and may thus restrict the efficacy of the physical therapy which is essential for treating hypokinetic-rigid symptoms. In selecting the appropriate medication for the treatment of any additional medical symptoms, which may arise, its limitations, contraindications and interactions with dopaminergic substances have to be taken into consideration. General medical symptoms and organ manifestations may also arise as a direct consequence of the autonomic dysfunction associated with Parkinson's disease. As the disease progresses, additional non-parkinsonian symptoms can be of concern. Furthermore, the side effects of Parkinson medications may necessitate the involvement of other medical specialists. In this review, we will discuss the various general medical aspects of Parkinson's disease.

Investigation on Abnormal Iron Metabolism and Related Inflammation in Parkinson Disease Patients with Probable RBD

Objective

To investigate potential mechanisms involving abnormal iron metabolism and related inflammation in Parkinson disease (PD) patients with probable rapid eye movement sleep behavior disorder (PRBD).

Methods

Total 210 PD patients and 31 controls were consecutively recruited. PD patients were evaluated by RBD Screening Questionnaire (RBDSQ) and classified into PRBD and probable no RBD (NPRBD) groups. Demographics information were recorded and clinical symptoms were evaluated by series of rating scales. Levels of iron and related proteins and inflammatory factors in cerebrospinal fluid (CSF) and serum were detected. Comparisons among control, NPRBD and PRBD groups and correlation analyses between RBDSQ score and levels of above factors were performed.

Results

(1)The frequency of PRBD in PD patients is 31.90%. (2)PRBD group has longer disease duration, more advanced disease stage, severer motor symptoms and more non-motor symptoms than NPRBD group. (3)In CSF, levels of iron, transferrin, NO and IL–1β in PRBD group are prominently increased. RBDSQ score is positively correlated with the levels of iron, transferrin, NO and IL–1β in PD group. Iron level is positively correlated with the levels of NO and IL–1β in PD group. (4)In serum, transferrin level is prominently decreased in PRBD group. PGE₂ level in PRBD group is drastically enhanced. RBDSQ score exhibits a positive correlation with PGE₂ level in PD group.

Conclusions

PRBD is common in PD patients. PRBD group has severer motor symptoms and more non-motor symptoms. Excessive iron in brain resulted from abnormal iron metabolism in central and peripheral systems is correlated with PRBD through neuroinflammation.

Plasma Homocysteine, Vitamin B12 and Folate Levels in Multiple System Atrophy: A Case-Control Study

Background

Multiple system atrophy (MSA) is a neurodegenerative disease, and its pathological hallmark is the accumulation of α-synuclein proteins. Homocysteine (Hcy) is an intermediate amino acid generated during the metabolism of methionine. Hcy may contribute to the pathogenesis of neurodegenerative disorders. Vitamin B12 and folate are cofactors necessary for the methylation of homocysteine.

Methods

This study compared the levels of serum Hcy, vitamin B12 and folate in patients with MSA with those in healthy people to reveal the possible association between MSA and plasma levels of Hcy, vitamin B12 and folate. We enrolled 161 patients with MSA and 161 healthy people in this study. The association between MSA and the levels of Hcy, vitamin B12 and folate were analyzed using binary logistic regression.

Results

The mean level of Hcy in patients with MSA was significantly higher than that in healthy controls (16.23 ± 8.09 umol/l vs 14.04 ± 4.25 umol/l, p < 0.05). After adjusting for age, sex and medical history, the odds ratio for Hcy was 1.07 (95% CI = 1.01–1.13, p < 0.05) for patients with MSA. Vitamin B12 and folate levels were not significantly different between patients with MSA and controls.

Conclusion

Our data suggest that higher levels of Hcy may be associated with an increased risk for MSA.

Association between sex, systemic iron variation and probability of Parkinson's disease

OBJECTIVE

Iron homeostasis appears altered in Parkinson's disease (PD). Recent genetic studies and meta-analyses have produced heterogeneous and inconclusive results. In order to verify the possible role of iron status in PD, we have screened some of the main metal gene variants, evaluated their effects on iron systemic status, and checked for possible interactions with PD.

MATERIALS AND METHODS

In 92 PD patients and 112 healthy controls, we screened the D544E and R793H variants of the ceruloplasmin gene (CP), the P589S variant of the transferrin gene (TF), and the H63D and C282Y variants of the HFE gene, encoding for homologous proteins, respectively. Furthermore, we analyzed serum concentrations of iron, copper and their related proteins.

RESULTS

The genetic investigation revealed no significant differences in allelic and genotype distributions between patients and controls. Two different multivariable forward stepwise logistic models showed that, when the effect of sex is considered, an increase of the probability of having PD is associated with low iron concentration and Tf-saturation.

CONCLUSIONS

This study provides new evidence of the involvement of iron metabolism in PD pathogenesis and reveals a biological effect of sex.

Eryptosis as a marker of Parkinson's disease

A major trend in recent Parkinson's disease (PD) research is the investigation of biological markers that could help in identifying at-risk individuals or to track disease progression and response to therapies. Central to this is the knowledge that inflammation is a known hallmark of PD and of many other degenerative diseases. In the current work, we focus on inflammatory signalling in PD, using a systems approach that allows us to look at the disease in a more holistic way. We discuss cyclooxygenases, prostaglandins, thromboxanes and also iron in PD. These particular signalling molecules are involved in PD pathophysiology, but are also very important in an aberrant coagulation/hematology system. We present and discuss a hypothesis regarding the possible interaction of these aberrant signalling molecules implicated in PD, and suggest that these molecules may affect the erythrocytes of PD patients. This would be observable as changes in the morphology of the RBCs and of PD patients relative to healthy controls. We then show that the RBCs of PD patients are indeed rather dramatically deranged in their morphology, exhibiting eryptosis (a kind of programmed cell death). This morphological indicator may have useful diagnostic and prognostic significance.

Unwanted effects and interaction of intrajejunal levodopa/carbidopa administration

INTRODUCTION

Levodopa is the most effective treatment for Parkinson's disease. After a number of years on treatment, fluctuations and dyskinesias may develop. Hence, invasive treatment measures are often needed (escalation therapy).

AREAS COVERED

Twenty years ago, a levodopa/carbidopa intestinal gel (LCIG) that can be infused directly into the jejunum was developed. This provides for continuous dopaminergic stimulation. For the past 10 years, LCIG has been licensed in some countries and its marketing approval is pending in the USA. It is endowed with very good efficacy, and in studies, it has proven to be superior to oral drug treatment. Continuous dopaminergic stimulation is also assured, and fluctuations and dyskinesias are significantly reduced. However, this technique involves an invasive procedure with percutaneous endoscopic gastrostomy and attendant surgical and postsurgical complications. Besides, there are problems related to the pump and tube. Vitamin deficiency and polyneuropathies are other drawbacks.

EXPERT OPINION

LCIG is a beneficial and very useful treatment option as escalation therapy for Parkinson's disease. While the side effects are not insignificant, they are justifiable in view of the severity of the disease. Attention must be paid, in particular, to malabsorption, with monitoring at baseline and in the course of treatment.