Helicobacter pylori infection, dementia and primary open-angle glaucoma: are they connected?

Association of Open-Angle Glaucoma With Dementia in California Medicare Beneficiaries

PURPOSE

To examine the associations between open-angle glaucoma (OAG) subtypes and dementia in 2019 California Medicare beneficiaries.

DESIGN

Retrospective cross-sectional study.

METHODS

OAG diagnosis was determined by the International Classification of Diseases, Tenth Revision (ICD-10), diagnosis codes in part B claims, including the following OAG subtypes: primary open-angle glaucoma (POAG), normal tension glaucoma (NTG), pseudoexfoliative glaucoma (PXG), and pigmentary glaucoma (PG). Diagnoses of any dementia, Alzheimer dementia (AD), frontotemporal dementia (FTD), Lewy body dementia (LBD), and vascular dementia (VD) were identified by ICD-10 diagnosis codes. Covariates included demographics, systemic diseases, depression, hearing loss, obesity, smoking and alcohol-related disorders, and long-term aspirin, anticoagulant, and antithrombotic or antiplatelet use. Univariate and multivariable logistic regression models were used to assess the associations between OAG and dementia, adjusting for all covariates. Age-stratified analysis was also performed for beneficiaries aged 65-74 years, 75-84 years, and ≥85 years.

RESULTS

Among the 2,431,150 California Medicare beneficiaries included in this study, 104,873 (4.3%) had POAG, 9199 (0.4%) had NTG, 4045 (0.2%) had PXG, and 1267 (0.05%) had PG. The overall prevalence of any dementia was 3.2% (n = 79,009). In adjusted analyses, the odds of any dementia were lower for beneficiaries with all OAG subtypes compared with beneficiaries without glaucoma (odds ratio [OR] = 0.74 for POAG, OR = 0.74 for PXG, OR = 0.60 for NTG, and OR = 0.38 for PG; P < .01). In age-stratified analyses, beneficiaries with PXG had greater odds of VD (OR 2.84, P = .006; aOR 2.18, P = .04) in the youngest age stratum (65-74 years) compared to patients with no glaucoma. The odds for any dementia were lower for beneficiaries with all OAG subtypes compared to beneficiaries without glaucoma in the oldest, but not in the youngest, age stratum.

CONCLUSIONS

In the 2019 California Medicare population, PXG is associated with an increased likelihood of VD in beneficiaries 65-74 years old, whereas other subtypes of POAG are associated with a decreased likelihood of any dementia. These findings may suggest selection bias because older adults who continue to follow up with glaucoma care may be more cognitively intact. Further studies are needed to better understand the complex relationship between glaucoma, dementia, and their subtypes.

Frequency of coexistent eye diseases and cognitive impairment or dementia: a systematic review and meta-analysis

OBJECTIVE

We aim to quantify the co-existence of age-related macular degeneration (AMD), glaucoma, or diabetic retinopathy (DR) and cognitive impairment or dementia.

METHOD

MEDLINE, EMBASE, PsycINFO and CINAHL were searched (to June 2020). Observational studies reporting incidence or prevalence of AMD, glaucoma, or DR in people with cognitive impairment or dementia, and of cognitive impairment or dementia among people with AMD, glaucoma, or DR were included.

RESULTS

Fifty-six studies (57 reports) were included but marked by heterogeneities in the diagnostic criteria or definitions of the diseases, study design, and case mix. Few studies reported on the incidence. Evidence was sparse but consistent in individuals with mild cognitive impairment where 7.7% glaucoma prevalence was observed. Prevalence of AMD and DR among people with cognitive impairment ranged from 3.9% to 9.4% and from 11.4% to 70.1%, respectively. Prevalence of AMD and glaucoma among people with dementia ranged from 1.4 to 53% and from 0.2% to 25.9%, respectively. Prevalence of DR among people with dementia was 11%. Prevalence of cognitive impairment in people with AMD, glaucoma, and DR ranged from 8.4% to 52.4%, 12.3% to 90.2%, and 3.9% to 77.8%, respectively, and prevalence of dementia in people with AMD, glaucoma and DR ranged from 9.9% to 62.6%, 2.5% to 3.3% and was 12.5%, respectively.

CONCLUSIONS

Frequency of comorbid eye disease and cognitive impairment or dementia varied considerably. While more population-based estimations of the co-existence are needed, interdisciplinary collaboration might be helpful in the management of these conditions to meet healthcare needs of an ageing population.

TRIAL REGISTRATION

PROSPERO registration: CRD42020189484.

Association between helicobacter pylori infection and primary open-angle glaucoma: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis summarize the evidence for the association between Helicobacter pylori infection and Primary Open-Angle Glaucoma.

METHODS

Eligible studies reporting an association between H. pylori infection and Glaucoma were identified through an extensive search of the Excerpta Medica (EMBASE), Web of Science, Scopus, and PubMed databases and an assessment of the reference list of the top articles until October 2022. Analysis was performed with random effects model using Stata 16.

RESULT

Twenty-four studies were included in the systematic review. This study involved 1602 glaucoma patients and 2800 control individuals. The combined RRs of cohort studies and overall combined ORs of case-control studies showed a significant correlation between H. pylori infection and Glaucoma. Subgroup analysis showed that glaucoma patients had a higher risk of having H. pylori infection if they were residents of Europe countries (Cohort: RR: 1.69; 95% CI: 1.3-2.19) and (Case-Control: RR: 3.71; 95% CI: 2.07-6.64), if they had POAG type (Cohort: RR: 1.76; 95% CI: 1.37-2.27) and (Case-Control: RR: 3.71; 95% CI: 2.934.70), if their diagnostic method of HP was histology (Cohort: RR: 1.95; 95% CI: 1.26-3.01) and (Case-Control: RR: 4.06; 95% CI: 2.28-7.22), and if they were over 60 years old (Cohort: RR: 1.63; 95% CI: 1.33-2.00) and (Case-Control: RR: 2.95; 95% CI: 2.27-3.83).

DISCUSSION

The results of this meta-analysis suggest a statistically significant association between Helicobacter pylori infection and Primary Open-Angle Glaucoma.

Beyond the amyloid hypothesis: how current research implicates autoimmunity in Alzheimer's disease pathogenesis

The amyloid hypothesis has so far been at the forefront of explaining the pathogenesis of Alzheimer's Disease (AD), a progressive neurodegenerative disorder that leads to cognitive decline and eventual death. Recent evidence, however, points to additional factors that contribute to the pathogenesis of this disease. These include the neurovascular hypothesis, the mitochondrial cascade hypothesis, the inflammatory hypothesis, the prion hypothesis, the mutational accumulation hypothesis, and the autoimmunity hypothesis. The purpose of this review was to briefly discuss the factors that are associated with autoimmunity in humans, including sex, the gut and lung microbiomes, age, genetics, and environmental factors. Subsequently, it was to examine the rise of autoimmune phenomena in AD, which can be instigated by a blood-brain barrier breakdown, pathogen infections, and dysfunction of the glymphatic system. Lastly, it was to discuss the various ways by which immune system dysregulation leads to AD, immunomodulating therapies, and future directions in the field of autoimmunity and neurodegeneration. A comprehensive account of the recent research done in the field was extracted from PubMed on 31 January 2022, with the keywords "Alzheimer's disease" and "autoantibodies" for the first search input, and "Alzheimer's disease" with "IgG" for the second. From the first search, 19 papers were selected, because they contained recent research on the autoantibodies found in the biofluids of patients with AD. From the second search, four papers were selected. The analysis of the literature has led to support the autoimmune hypothesis in AD. Autoantibodies were found in biofluids (serum/plasma, cerebrospinal fluid) of patients with AD with multiple methods, including ELISA, Mass Spectrometry, and microarray analysis. Through continuous research, the understanding of the synergistic effects of the various components that lead to AD will pave the way for better therapeutic methods and a deeper understanding of the disease.

Update to the Treatment of Parkinson's Disease Based on the Gut-Brain Axis Mechanism

Gastrointestinal (GI) symptoms represented by constipation were significant non-motor symptoms of Parkinson’s disease (PD) and were considered early manifestations and aggravating factors of the disease. This paper reviewed the research progress of the mechanism of the gut-brain axis (GBA) in PD and discussed the roles of α-synuclein, gut microbiota, immune inflammation, neuroendocrine, mitochondrial autophagy, and environmental toxins in the mechanism of the GBA in PD. Treatment of PD based on the GBA theory has also been discussed, including (1) dietary therapy, such as probiotics, vitamin therapy, Mediterranean diet, and low-calorie diet, (2) exercise therapy, (3) drug therapy, including antibiotics; GI peptides; GI motility agents, and (4) fecal flora transplantation can improve the flora. (5) Vagotomy and appendectomy were associated but not recommended.

Preventive Measures against the Development of Dementia in Old Age

Dementia is a neurological condition characterized by numerous types of central nervous system diseases, which gradually deteriorates an individual’s reasoning, rational thinking, and judgment abilities. As a serious public health concern that currently affects more than 50 million older adults, dementia is one of the most significant causes of incapacity, disability, and dependency among older adults. As new cases are expected to increase exponentially in the next three decades, dementia, which is not a normal feature of healthy aging despite the fact that it generally affects older adults disproportionately, requires enormous management and care efforts due to its associated socioeconomic, psychological, and physical burdens that involve the patient, their caregivers, guardians, family members, and society at large. Presently, there is no cure for dementia; however, this condition could be prevented. This narrative review aimed to provide a broad overview of studies detailing the alternative lifestyle modification-centered preventive measures against dementia. A comprehensive search of key databases to find articles related to this topic revealed that participating in regular physical activities, healthy eating and dieting, avoiding all forms of smoking, avoiding air pollutants, halting or reducing alcohol consumption, exercising the mind and being socially dynamic, getting enough rest and establishing good sleeping habits, infection prevention, stress prevention, avoidance of injuries, preventing the effects of social isolation and lockdowns, continuing education, and depression prevention are protective measures against the development of dementia.

Helicobacter pylori infection and risk for developing dementia: an evidence-based meta-analysis of case-control and cohort studies

BACKGROUND

Infection with multiple pathogens may play a key role in the pathogenesis of dementia. Whether Helicobacter pylori (H. pylori) infection is associated causally with dementia is controversial.

OBJECTIVE

We conduct a meta-analysis of case-control and cohort studies on the association between H. pylori infection and the risk for all-cause and Alzheimer's disease (AD) dementia.

METHODS

Two independent reviewers searched the PubMed, Cochrane Library, and Embase databases with English language restrictions from the date of conception to September 18, 2020. The primary analysis was as follows: the exposure variable was H. pylori infection, and the outcome was incident all-cause and AD dementia. Pooled odds ratios (OR), relative risk (RR), and corresponding 95% confidence intervals (CI) were obtained using the fixed-or random-effect model. Forest plots were generated to summarize the results.

RESULTS

Ten studies involving 96,561 participants were included in the meta-analysis: 5 case-control studies and 5 cohort studies. The overall pooled cohort studies showed a significant positive association between H. pylori infection and all-cause dementia with pooled RR of 1.36 (95% CI, 1.11-1.67). There was no association between H. pylori infection and risk for developing AD: RR of 1.33 (95% CI, 0.86-2.05) in cohort studies, and OR of 1.72 (95% CI, 0.97-3.04) in case-control studies. Significant heterogeneity was showed in each comparison group.

CONCLUSION

This meta-analysis supports a positive association between H. pylori infection and the risk of all-cause dementia, but not AD dementia. Due to the interference of confounding factors, randomized controlled trials are needed to prove their causality.

Glaucoma Is Not Associated With Alzheimer's Disease or Dementia: A Meta-Analysis of Cohort Studies

Background: Previous studies evaluating the relationships of glaucoma with Alzheimer's disease (AD) and dementia showed inconsistent results. We performed a meta-analysis of cohort studies to evaluate the association between glaucoma with incidence of AD, all-cause dementia, and non-AD dementia. Methods: Cohort studies which evaluated the association between glaucoma with incidence of AD, all-cause dementia, and non-AD dementia in adult population with multivariate analyses were identified by systematic search of PubMed, Embase, and Cochrane's Library databases. A random-effects model incorporating the potential intra-study heterogeneity was used for the meta-analysis. Results: Eleven cohort studies including 4,645,925 participants were included. Results showed that compared to those without glaucoma at baseline, adult patients with glaucoma was not independently associated with increased incidence of AD [adjusted risk ratio (RR): 1.03, 95% confidence interval (CI): 0.93-1.05, P = 0.55; I ² = 83%], all-cause dementia (adjusted RR: 1.08, 95% CI: 0.97-1.19, P = 0.15; I ² = 79%), or non-AD dementia (adjusted RR: 1.05 95% CI: 0.91-1.21, P = 0.49; I ² = 82%). Sensitivity analyses by excluding one study at a time did not significantly affect the results of the meta-analyses. Moreover, subgroup analyses showed consistent results in meta-analysis of prospective or retrospective cohort studies, and in meta-analysis of patients with primary open-angle glaucoma or primary angle-closure glaucoma (P-values for subgroup difference all > 0.05). Conclusions: Current evidence from cohort studies did not support that glaucoma is an independent risk factor of AD, all-cause dementia, or non-AD dementia in adult population.

Infections and glaucoma

Glaucoma is an intraocular pressure-related ophthalmic disease with multiple causes that results in an optic neuropathy and vision loss. Intraocular pressure elevation is among its strongest risk factors. While glaucoma is mostly primary in etiology, secondary glaucoma is not infrequent. Recognizing its cause is imperative, since treatment is often different depending on the pathophysiologic mechanism. Numerous clinically relevant ophthalmic infections can result in robust inflammatory responses that may result in pressure elevation or intraocular anatomic configurations that predispose to pressure elevation. Knowing the mechanisms by which these infections can lead to glaucoma is critical in treating, and we consolidate what is currently known in regards to how infectious diseases lead to glaucoma.

The trimebutine effect on Helicobacter pylori-related gastrointestinal tract and brain disorders: A hypothesis

The localization of bacterial components and/or metabolites in the central nervous system may elicit neuroinflammation and/or neurodegeneration. Helicobacter pylori (a non-commensal symbiotic gastrointestinal pathogen) infection and its related metabolic syndrome have been implicated in the pathogenesis of gastrointestinal tract and central nervous system disorders, thus medications affecting the nervous system - gastrointestinal tract may shape the potential of Helicobacter pylori infection to trigger these pathologies. Helicobacter pylori associated metabolic syndrome, by impairing gut motility and promoting bacterial overgrowth and translocation, might lead to brain pathologies. Trimebutine maleate is a prokinetic drug that hastens gastric emptying, by inducing the release of gastrointestinal agents such as motilin and gastrin. Likewise, it appears to protect against inflammatory signal pathways, involved in inflammatory disorders including brain pathologies. Trimebutine maleate also acts as an antimicrobial agent and exerts opioid agonist effect. This study aimed to investigate a hypothesis regarding the recent advances in exploring the potential role of gastrointestinal tract microbiota dysbiosis-related metabolic syndrome and Helicobacter pylori in the pathogenesis of gastrointestinal tract and brain diseases. We hereby proposed a possible neuroprotective role for trimebutine maleate by altering the dynamics of the gut-brain axis interaction, thus suggesting an additional effect of trimebutine maleate on Helicobacter pylori eradication regimens against these pathologies.

Association between Active Helicobacter pylori Infection and Glaucoma: A Systematic Review and Meta-Analysis

Background: Glaucoma is the second most common cause of blindness worldwide affecting almost 70 million individuals. Helicobacter pylori (H. pylori) is a widespread pathogen with systematic pathogenicity. This meta-analysis aimed to estimate the contradictory data regarding a potential association between active H. pylori infection and glaucoma. Materials and Methods: A research in MEDLINE/PubMed and Google Scholar was conducted and original studies investigating the relationship between H. pylori infection and glaucoma were included. Analysis was performed with random effects model. The main outcome was the odds ratio (OR) with 95% confidence intervals (CI) of H. pylori infection as a risk factor for glaucoma. A parallel analysis studied the role of active infection as indicated by histology and the titer of anti-H. pylori antibodies. For the anti-H. pylori antibody titers, weighted mean differences (WMD) were estimated between patients and controls. Results: Fifteen studies were included, with 2664 participants (872 patients with glaucoma and 1792 controls), divided into primary open-angle glaucoma (POAG), normal tension glaucoma (NTG) and pseudo-exfoliation glaucoma (PEG). The association between H. pylori infection and overall glaucoma was significant (OR = 2.08, CI 95% 1.48–2.93) with moderate heterogeneity (I² = 61.54%). After stratification by glaucoma subtype, heterogeneity was eliminated in the NTG subgroup. Studies with healthy controls, and controls with anemia yielded very low or no heterogeneity, respectively. Gastric biopsy to document active H. pylori infection yielded the highest OR (5.4, CI: 3.17–9.2, p < 0.001) and null heterogeneity. For anti-H. pylori antibody titers, there was a significant difference in WMD between patients and controls (WMD 15.98 IU/mL; 95% CI: 4.09–27.87; p = 0.008); values were greater in glaucoma patients, with high heterogeneity (I²: 93.8%). Meta-regression analysis showed that mean age had a significant impact on glaucoma (p = 0.037). Conclusions: Active H. pylori infection may be associated with glaucoma with null heterogeneity, as, beyond histology, quantified by anti-H. pylori titers and increases with age.

Bacterial, viral, and fungal infection-related risk of Parkinson's disease: Meta-analysis of cohort and case-control studies

AIMS

Recent studies showed that patients with various bacterial, viral, and fungal infections might be at increased risk of Parkinson's disease (PD). However, the risk of PD in patients with each specific infection varied. This meta-analysis estimated the association between various infections and PD risk.

METHODS

Literature published from January 1965 to October 2019 in PubMed and EMBASE databases was searched. Data were extracted and pooled using random/fixed effects model. Sensitivity analysis and meta-regression were also performed to analyze the source of heterogeneity. Publication bias was estimated by the trim and fill.

RESULTS

Twenty-three out of 6,609 studies were included. Helicobacter pylori (HP; pooled OR = 1.653, 1.426-1.915, p < .001), hepatitis C virus (HCV; pooled OR = 1.195, 1.012-1.410, p = .035), Malassezia (pooled OR = 1.694, 1.367-2.100, p < .001), and pneumoniae (pooled OR = 1.595, 1.020-2.493, p = .041) infection were associated with increased PD risk. Influenza virus, herpes virus, hepatitis B virus, scarlet fever, mumps virus, chicken pox, pertussis, German measles, and measles were not associated with PD risk. After antiviral treatment against HCV reduced the risk of PD in patients with HCV infection (OR = 0.672, 0.571-0.791, p < .001). Significant heterogeneity exists among the included studies.

CONCLUSION

Patients with infection of HP, HCV, Malassezia, pneumoniae might be an increased risk of PD. Antiviral treatment of HCV could reduce the risk of PD.

Association of Intestinal Disorders with Parkinson's Disease and Alzheimer's Disease: A Systematic Review and Meta-Analysis

Parkinson's disease (PD) and Alzheimer's disease (AD) are the most common neurodegenerative disorders, with an overall global incidence of 40 million. Many studies have revealed the association of intestinal disorders and bacterial infections with PD, but few studies have found such a relationship with AD. In this meta-analysis, related articles published up to September 2018 were searched in PubMed. Of the 2121 related articles screened initially, 56 were found to be eligible. Data on the risks of PD and AD due to five intestinal disorders and infection with Helicobacter pylori, as a representative intestinal microbe, were obtained, and a fixed- or random-effects model was used to pool the odds ratios (ORs) with 95% confidence interval (CIs) from individual studies. The combined OR for all types of intestinal disorders with an increased risk of PD was 3.36 (95% CI: 2.70-4.17). The ORs for each category were as follows: constipation, 4.05 (95% CI, 3.24-5.06); inflammatory bowel disease (IBD), 1.16 (95% CI, 0.89-1.52); irritable bowel syndrome (IBS), 1.75 (95% CI, 0.55-5.56); small intestinal bacterial overgrowth, 5.15 (95% CI, 3.33-7.96); and diarrhea, 1.27 (95% CI, 0.28-5.75). The combined OR of all types of intestinal disorders with an increased risk of AD was 1.52 (95% CI, 1.09-2.13). The ORs for IBS and IBD were 1.42 (95% CI, 1.02-1.99) and 2.40 (95% CI, 1.00-5.76), respectively. The risk estimates of H. pylori infection in PD and AD patients were as follows: OR, 1.65 (95% CI, 1.43-1.91) and OR, 1.40 (95% CI, 1.12-1.76), respectively. These findings suggest that PD and AD are significantly associated with intestinal disorders. The negative roles of H. pylori in the development of PD or AD should be evaluated to shed new light on the diagnosis and treatment of PD and AD. National governments should periodically inspect the intestinal condition of residents and extend health plans to improve intestinal health to prevent potential neurological disorders.

Helicobacter pylori eradication regimens in an antibiotic high-resistance European area: A cost-effectiveness analysis

INTRODUCTION

Helicobacter pylori infection (H pylori-I) affects more than half of the global population and consists an important burden to public health and healthcare expenditures, by contributing to many diseases' pathogenesis.

AIM

This study aimed to evaluate the current nonbismuth quadruple eradication regimens in a high antibiotic resistance area, such as Greece, concerning their cost-effectiveness, especially during financial crisis period.

MATERIALS AND METHODS

Eight hundred and nine patients who received eradication treatment against H pylori-I were included to evaluate five different regimens, using amoxicillin, clarithromycin, and metronidazole as antibiotics and one proton-pump inhibitor, based on their current eradication rates. Regimes compared 10-day concomitant use of (a) pantoprazole or (b) esomeprazole; 10-day sequential use of (c) pantoprazole or (d) esomeprazole; and 14-day hybrid using esomeprazole. Cost-effectiveness analysis ratio (CEAR) and incremental cost-effectiveness ratios were calculated taking into account all direct costs and cases who needed second-line treatment. Additionally, sensitivity analysis was performed to predict all potential combinations.

RESULTS

Ten-day concomitant regimen with esomeprazole was characterized by the lowest CEAR (179.17€) followed by the same regimen using pantoprazole (183.27€). Hybrid regimen, although equivalent in eradication rates, was found to have higher CEAR (187.42€), whereas sequential regimens were not cost-effective (CEAR: 204.12€ and 216.02€ respectively).

DISCUSSION

This is the first study evaluating the cost-effectiveness of H pylori-I treatment regimens in a high clarithromycin-resistance (≈26.5%) European area, suggesting the 10-day concomitant regimen with generics using esomeprazole 40 mg as the most appropriate one. National and regional guidelines should include cost-effectiveness in their statements, and further studies are required to clarify the necessity of a wide "test and treat" policy for H pylori-I.

Machine Learning-Based Predictive Modeling of Surgical Intervention in Glaucoma Using Systemic Data From Electronic Health Records

PURPOSE

To predict the need for surgical intervention in patients with primary open-angle glaucoma (POAG) using systemic data in electronic health records (EHRs).

DESIGN

Development and evaluation of machine learning models.

METHODS

Structured EHR data of 385 POAG patients from a single academic institution were incorporated into models using multivariable logistic regression, random forests, and artificial neural networks. Leave-one-out cross-validation was performed. Mean area under the receiver operating characteristic curve (AUC), sensitivity, specificity, accuracy, and Youden index were calculated for each model to evaluate performance. Systemic variables driving predictions were identified and interpreted.

RESULTS

Multivariable logistic regression was most effective at discriminating patients with progressive disease requiring surgery, with an AUC of 0.67. Higher mean systolic blood pressure was associated with significantly increased odds of needing glaucoma surgery (odds ratio [OR] = 1.09, P < .001). Ophthalmic medications (OR = 0.28, P < .001), non-opioid analgesic medications (OR = 0.21, P = .002), anti-hyperlipidemic medications (OR = 0.39, P = .004), macrolide antibiotics (OR = 0.40, P = .03), and calcium blockers (OR = 0.43, P = .03) were associated with decreased odds of needing glaucoma surgery.

CONCLUSIONS

Existing systemic data in the EHR has some predictive value in identifying POAG patients at risk of progression to surgical intervention, even in the absence of eye-specific data. Blood pressure-related metrics and certain medication classes emerged as predictors of glaucoma progression. This approach provides an opportunity for future development of automated risk prediction within the EHR based on systemic data to assist with clinical decision-making.

Altered Gut Microbiome and Intestinal Pathology in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder arising from an interplay between genetic and environmental risk factors. Studies have suggested that the pathological hallmarks of intraneuronal α-synuclein aggregations may start from the olfactory bulb and the enteric nervous system of the gut and later propagate to the brain via the olfactory tract and the vagus nerve. This hypothesis correlates well with clinical symptoms, such as constipation, that may develop up to 20 years before the onset of PD motor symptoms. Recent interest in the gut-brain axis has led to vigorous research into the gastrointestinal pathology and gut microbiota changes in patients with PD. In this review, we provide current clinical and pathological evidence of gut involvement in PD by summarizing the changes in gut microbiota composition and gut inflammation associated with its pathogenesis.

H. pylori and Parkinson's disease: Meta-analyses including clinical severity

The exact etiology of Parkinson's disease (PD) remains unclear. Some evidence supports Helicobacter pylori infection as a trigger or driving event, but detection and eradication of H. pylori are not part of PD management. The aims of this case-control study and meta-analysis were to determine (i) the prevalence of H. pylori infection in PD patients, (ii) associations between H. pylori infection and clinical status, and (iii) differences in motor status in PD patients before and after H. pylori eradication. A literature search was performed using the PubMed database. The prevalence of H. pylori infection in PD, its association with the unified Parkinson's disease rating scale (UPDRS), and the association of H. pylori eradication therapy with the UPDRS-III score were determined by calculating the odds ratios (OR) and the standardized mean differences (SMD) with 95% confidence intervals (CI). Fixed- and random-effects models were applied. Ten studies were included in the first meta-analysis (5043 PD patients, 23,449 HCs); H. pylori infection prevalence was higher in PD patients than in HCs [OR (95% CI): 1.47 (1.27, 1.70), P_z<0.00001]. In seven studies reporting UPDRS scores (150 H. pylori infected, 228 non-infected PD patients), there was a significant association between H. pylori infection and mean UPDRS scores [SMD (95% CI): 0.33 (0.12, 0.54), P_z = 0.003]. Regarding H. pylori eradication, in five studies (90 PD patients), there was a significant reduction in UPDRS-III scores after treatment [SMD (95% CI): 6.83 (2.29, 11.38), P_z = 0.003]. In conclusion, the present meta-analysis revealed a higher prevalence of H. pylori infection in PD patients suggesting that H. pylori may contribute to PD pathophysiology. In addition, the significantly lower UPDRS scores in non-infected PD patients and in patients after H. pylori eradication therapy demonstrate that the infection may deteriorate the clinical severity of the disease.

Review: Impact of Helicobacter pylori on Alzheimer's disease: What do we know so far?

BACKGROUND

Helicobacter pylori has changed radically gastroenterologic world, offering a new concept in patients' management. Over time, more medical data gave rise to diverse distant, extragastric manifestations and interactions of the "new" discovered bacterium. Special interest appeared within the field of neurodegenerative diseases and particularly Alzheimer's disease, as the latter and Helicobacter pylori infection are associated with a large public health burden and Alzheimer's disease ranks as the leading cause of disability. However, the relationship between Helicobacter pylori infection and Alzheimer's disease remains uncertain.

METHODS

We performed a narrative review regarding a possible connection between Helicobacter pylori and Alzheimer's disease. All accessible relevant (pre)clinical studies written in English were included. Both affected pathologies were briefly analyzed, and relevant studies are discussed, trying to focus on the possible pathogenetic role of this bacterium in Alzheimer's disease.

RESULTS

Data stemming from both epidemiologic studies and animal experiments seem to be rather encouraging, tending to confirm the hypothesis that Helicobacter pylori infection might influence the course of Alzheimer's disease pleiotropically. Possible main mechanisms may include the bacterium's access to the brain via the oral-nasal-olfactory pathway or by circulating monocytes (infected with Helicobacter pylori due to defective autophagy) through disrupted blood-brain barrier, thereby possibly triggering neurodegeneration.

CONCLUSIONS

Current data suggest that Helicobacter pylori infection might influence the pathophysiology of Alzheimer's disease. However, further large-scale randomized controlled trials are mandatory to clarify a possible favorable effect of Helicobacter pylori eradication on Alzheimer's disease pathophysiology, before the recommendation of short-term and cost-effective therapeutic regimens against Helicobacter pylori-related Alzheimer's disease.

Meta-analysis: Association of Helicobacter pylori infection with Parkinson's diseases

BACKGROUND

The results from observational studies on the relationship between helicobacter pylori (H. pylori) infection and Parkinson's disease remain controversial. A meta-analysis was conducted to evaluate the association between helicobacter pylori infection and Parkinson's disease.

METHODS

A comprehensive literature search was performed on relevant studies published from January 1983 to January 2017 in PubMed, Web of Science and EMBASE databases. The fixed or random effects model was used to pool the odds ratio with 95% confidence interval from individual studies. Publication bias was estimated by Egger's test and the funnel plot.

RESULTS

Eight eligible studies involving 33 125 participants were included in this meta-analysis. Compared with the no helicobacter pylori infected person, the pooled odds ratio of Parkinson's disease in helicobacter pylori infected person was 1.59 (95% confidence interval: 1.37-1.85). In subgroup analyzes, the combined odds ratios were 1.96 (1.23-3.12) in Asia, 1.55 (1.32-1.82) in Europe, 1.59 (1.35-1.88) in case-control studies, 1.56 (1.01-2.39) in cross-sectional studies, 1.56 (1.32-1.85) in studies with confounders adjusted, and 1.71 (1.21-2.43) in studies with no confounder adjusted, respectively.

CONCLUSIONS

This meta-analysis indicated that H. pylori infection might be associated with the risk of Parkinson's disease.

Helicobacter pylori and gut microbiota in multiple sclerosis versus Alzheimer's disease: 10 pitfalls of microbiome studies

Alteration of microbiota has been associated with intestinal, inflammatory, and neurological diseases. Abundance of "good bacteria" such as Bifidobacterium, or their products have been generally believed to be beneficial for any diseases, while "bad bacteria" such as pathogenic Helicobacter pylori are assumed to be always detrimental for hosts. However, this is not the case when we compare and contrast the association of the gut microbiota with two neurological diseases, multiple sclerosis (MS) and Alzheimer's disease (AD). Following H. pylori infection, pro-inflammatory T helper (Th)1 and Th17 immune response are initially induced to eradicate bacteria. However, H. pylori evades the host immune response by inducing Th2 cells and regulatory T cells (Tregs) that produce anti-inflammatory interleukin (IL)-10. Suppression of anti-bacterial Th1/Th17 cells by Tregs may enhance gastric H. pylori propagation, followed by a cascade reaction involving vitamin B₁₂ and folic acid malabsorption, plasma homocysteine elevation, and reactive oxygen species induction. This can damage the blood-brain barrier (BBB), leading to accumulation of amyloid-β in the brain, a hallmark of AD. On the other hand, this suppression of pro-inflammatory Th1/Th17 responses to H. pylori has protective effects on the hosts, since it prevents uncontrolled gastritis as well as suppresses the induction of encephalitogenic Th1/Th17 cells, which can mediate neuroinflammation in MS. The above scenario may explain why chronic H. pylori infection is positively associated with AD, while it is negatively associated with MS. Lastly, we list "10 pitfalls of microbiota studies", which will be useful for evaluating and designing clinical and experimental microbiota studies.

Association between Helicobacter pylori infection and carotid atherosclerosis in patients with vascular dementia

BACKGROUND AND PURPOSE

Accumulating evidence indicates that various infections contribute to the pathogenesis of atherosclerosis. Helicobacter pylori (Hp) has been implicated as a risk factor of atherosclerosis for stroke and other cardiovascular disease, but limited data exist regarding vascular dementia (VD). This study aimed to investigate the relationship between Hp infection and carotid atherosclerosis in patients with VD.

METHODS

A total of 354 patients who were diagnosed with VD were enrolled. Patients were divided into Hp positive VD group (n=208) and Hp negative VD group (n=156) using the (13)C-urea breath test ((13)C-UBT). Serum YKL-40, a marker for inflammation, were analyzed by ELISA. Traditional atherosclerotic risk factors including age, gender, body mass index (BMI), total cholesterol (TC), low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), triglycerides (TG), systolic blood pressure (SBP), diastolic blood pressure (DBP) and fasting blood glucose (FBG) were collected or detected. Carotid intima-media thickness (CIMT) was determined by color Doppler ultrasound.

RESULTS

CIMT values and serum YKL-40 significantly increased in Hp positive VD group in comparison with Hp negative VD group (p<0.05). In Hp positive VD group, serum YKL-40 was positively correlated with CIMT (r=0.412, p<0.05), and the association was independent of traditional atherosclerotic risk factors (β=0.381, p<0.001).

CONCLUSIONS

CIMT and serum YKL-4 were significantly higher in Hp positive patients than Hp negative patients. Hp-induced inflammation may be a risk factor for atherosclerosis in patients with VD.

Extragastric Diseases and Helicobacter pylori

The extragastric manifestations of Helicobacter pylori infection still remain a very strong topic throughout the H. pylori world. Indeed, H. pylori may interfere with many biological processes, both inside and outside of the stomach, possibly influencing or determining the occurrence of many diseases outside of the stomach. While its role in idiopathic thrombocytopenic purpura and sideropenic anemia has already been recognized, emerging evidence suggests that H. pylori may increase the risk of acute coronary syndrome, contribute to insulin resistance and be associated with neurodegenerative, respiratory, and other miscellaneous disorders previously associated with other conditions. Different pathogenic mechanisms have been hypothesized, including the induction of a low-grade inflammatory state and the occurrence of molecular mimicry mechanisms. This review summarizes the results of the most relevant studies published on this topic in the last year.