Interaction between Helicobacter pylori and latent toxoplasmosis and demographic variables on cognitive function in young to middle-aged adults

Helicobacter pylori-Toxoplasma gondii interplay with a possible role of IL-10

Parasites are known for their modulatory effects on the immune response. The impact of toxoplasmosis on the immune response towards H. pylori is being studied in terms of IL-10 levels. This study included 110 patients suffering from persistent dyspepsia and 50 apparently healthy controls. Stool samples were collected and tested for H. pylori using colloidal gold one step test. Sera were examined for anti-Toxoplasma IgM and IgG using ELISA. IL-10 was also tested in the sera using ELISA. We found that Toxoplasma IgM and IgG tested positive in 1.8 % and 40 % of H. pylori positive patients, respectively. H. pylori-infected patients displayed higher IL-10 levels than the healthy controls (84 versus 0.59 pg/ml, respectively, P < 0.001). Classification of H. pylori positive patients according to Toxoplasma IgG titers yielded three groups: negative (58, 52.7 %), equivocal (8, 7.3 %), and positive (44, 40 %) groups, with the highest IL-10 levels detected in the double positive than the negative and the equivocal group (215 pg/ml versus 43 and 112.5 pg/ml, respectively, P < 0.001). There was strong positive correlation between Toxoplasma IgG titers and IL-10 levels (rs = 0.82, P < 0.001). Toxoplasma enhances IL-10 production in response to H. pylori infection. This could ameliorate the inflammatory response in the gastric mucosa, and subsequently more colonization with the H. pylori is achieved, resulting in persistent infection.

Helicobacter pylori, persistent infection burden and structural brain imaging markers

Persistent infections, whether viral, bacterial or parasitic, including Helicobacter pylori infection, have been implicated in non-communicable diseases, including dementia and other neurodegenerative diseases. In this cross-sectional study, data on 635 cognitively normal participants from the UK Biobank study (2006-21, age range: 40-70 years) were used to examine whether H. pylori seropositivity (e.g. presence of antibodies), serointensities of five H. pylori antigens and a measure of total persistent infection burden were associated with selected brain volumetric structural MRI (total, white, grey matter, frontal grey matter (left/right), white matter hyperintensity as percent intracranial volume and bi-lateral sub-cortical volumes) and diffusion-weighted MRI measures (global and tract-specific bi-lateral fractional anisotropy and mean diffusivity), after an average 9-10 years of lag time. Persistent infection burden was calculated as a cumulative score of seropositivity for over 20 different pathogens. Multivariable-adjusted linear regression analyses were conducted, whereby selected potential confounders (all measures) and intracranial volume (sub-cortical volumes) were adjusted, with stratification by Alzheimer's disease polygenic risk score tertile when exposures were H. pylori antigen serointensities. Type I error was adjusted to 0.007. We report little evidence of an association between H. pylori seropositivity and persistent infection burden with various volumetric outcomes (P > 0.007, from multivariable regression models), unlike previously reported in past research. However, H. pylori antigen serointensities, particularly immunoglobulin G against the vacuolating cytotoxin A, GroEL and outer membrane protein antigens, were associated with poorer tract-specific white matter integrity (P < 0.007), with outer membrane protein serointensity linked to worse outcomes in cognition-related tracts such as the external capsule, the anterior limb of the internal capsule and the cingulum, specifically at low Alzheimer's disease polygenic risk. Vacuolating cytotoxin A serointensity was associated with greater white matter hyperintensity volume among individuals with mid-level Alzheimer's disease polygenic risk, while among individuals with the highest Alzheimer's disease polygenic risk, the urease serointensity was consistently associated with reduced bi-lateral caudate volumes and the vacuolating cytotoxin A serointensity was linked to reduced right putamen volume (P < 0.007). Outer membrane protein and urease were associated with larger sub-cortical volumes (e.g. left putamen and right nucleus accumbens) at middle Alzheimer's disease polygenic risk levels (P < 0.007). Our results shed light on the relationship between H. pylori seropositivity, H. pylori antigen levels and persistent infection burden with brain volumetric structural measures. These data are important given the links between infectious agents and neurodegenerative diseases, including Alzheimer's disease, and can be used for the development of drugs and preventive interventions that would reduce the burden of those diseases.

Peripheral inflammation is a potential etiological factor in Alzheimer's disease

Peripheral inflammation could constitute a risk factor for AD. This review summarizes the research related to peripheral inflammation that appears to have a relationship with Alzheimer's disease. We find there are significant associations between AD and peripheral infection induced by various pathogens, including herpes simplex virus type 1, cytomegalovirus, Epstein-Barr virus, human immunodeficiency virus, severe acute respiratory syndrome coronavirus 2, Porphyromonas gingivalis, Helicobacter pylori, and Toxoplasma gondii. Chronic inflammatory diseases are also reported to contribute to the pathophysiology of AD. The mechanisms by which peripheral inflammation affects the pathophysiology of AD are complex. Pathogen-derived neurotoxic molecule composition, disrupted BBB, and dysfunctional neurogenesis may all play a role in peripheral inflammation, promoting the development of AD. Anti-pathogenic medications and anti-inflammatory treatments are reported to decrease the risk of AD. Studies that could improve understanding the associations between AD and peripheral inflammation are needed. If our assumption is correct, early intervention against inflammation may be a potential method of preventing and treating AD.

A review on nonviral, nonbacterial infectious agents toxicity involved in neurodegenerative diseases

Neuronal death, decreased activity or dysfunction of neurotransmitters are some of the pathophysiological reasons for neurodegenerative diseases like Alzheimer's, Parkinson's and multiple sclerosis. Also, there is evidence for the role of infections and infectious agents in neurodegenerative diseases and the effect of some metabolites in microorganisms in the pathophysiology of these diseases. In this study, we intend to evaluate the existing studies on the role of infectious agents and their metabolites on the pathophysiology of neurodegenerative diseases. PubMed, Scopus, Google Scholar and Web of Science search engines were searched. Some infectious agents have been observed in neurodegenerative diseases. Also, isolations of some fungi and microalgae have an improving effect on Parkinson's and Alzheimer's.

Cognitive function in UK adults seropositive for Helicobacter pylori

Associated with gastritis, peptic-ulcer disease, and gastric carcinoma, Helicobacter pylori (H. pylori) also has been associated with decreased cognitive function and dementia. In this study, we used data from the UK Biobank to further examine associations between H. pylori seropositivity and serointensity and performance on several cognitive tasks in adults 40 to 70 years of age (M = 55.3, SD = 8.1). In these analyses, H. pylori seropositivity (i.e., either positive or negative for H. pylori) and serointensity (concentration of antibodies against H. pylori antigens) in adjusted models were associated with worse function on tasks of Numeric memory, Reasoning, and errors on the Pairs matching test but better function on the Tower rearrangement task. Together, these findings suggest that H. pylori seropositivity and serointensity might be associated with worse cognitive function in this age group.

Apolipoprotein ɛ4-Associated Protection Against Pediatric Enteric Infections is a Survival Advantage in Pre-Industrial Populations

Until 300,000 years ago, ancestors of modern humans ubiquitously carried the apolipoprotein E (APOE) ɛ4/ɛ4 genotype, when the ɛ3 allele mutated from the ancestral ɛ4, which elevates the risk of Alzheimer's disease. Modern humans living today predominantly carry the ɛ3 allele, which provides protection against heart disease and dementia in long-lived populations. The ancestral ɛ4 allele has been highly preserved in isolated populations in tropical and Arctic regions with high pathogen burdens, e.g., helminths. Early humans experienced serious enteric infections that exerted evolutionary selection pressure, and factors that mitigate infant and childhood mortality from enteric infections also exert selection pressure. Some bacteria can exploit the host's defensive inflammatory response to colonize and invade the host. Pathogen-induced inflammation associated with infant and childhood diarrhea can damage the gut wall long after the invading organisms are no longer present. Inflammation not only resides in the mucosal wall, but also induces systemic inflammation. Baseline systemic inflammation is lower in ɛ4 carriers, yet ɛ4 carriers display a stronger host inflammatory response that reduces pathogen burdens, increasing infant and early childhood survival. Evolutionary selection of the ɛ3 allele likely occurred after humans moved into temperate zones with lower pathogen burdens, unrelated to protection from Alzheimer's disease.

Comparison of Sequential, Hybrid, and Quadruple Therapy Protocols in Helicobacter pylori Eradication: A Single-Center Study

OBJECTIVE

Many treatment protocols are used in Helicobacter pylori eradication treatment within the framework of factors such as antibiotic resistance, drug side effects, patient compliance, and regional differences.

MATERIALS AND METHODS

H. pylori was diagnosed with upper gastrointestinal system endoscopic biopsy in the Internal Diseases Gastroenterology Endoscopy Unit of Atatürk University Medical Faculty Hospital; a total of 229 patients over the age of 18 were evaluated prospectively by dividing them into 3 groups and applying 3 different H. pylori eradication treatment protocols.

RESULTS

A total of 229 patients who completed the treatment were included in the study. H. pylori eradication was achieved in 186 patients and not achieved in 43 patients. The H. pylori eradication success of our study was found to be 81.2%. Among the 84 patients in group 1, while H. pylori eradication was achieved in 67 of them, it was not achieved in 17 patients. The eradication success of quadruple treatment with bismuth was 79.8%. Also, among the 68 patients in group 2, while H. pylori eradication was achieved in 55 patients, it was not achieved in 13. The eradication success of the 14-day hybrid treatment was 80.9%. Among the 77 patients in group 3, while H. pylori eradication was achieved in 64 patients, it was not achieved in 13. The eradication success of the 10-day sequential treatment was 83.1%.

CONCLUSION

It is necessary to conduct studies to find the most successful eradication regimen in primary care treatment of H. pylori in our country, to determine the regional antibiotic resistance rates, to individualize the proton pump inhibitor treatment due to metabolism and resistance differences, to examine the factors that stop from achieving the desired eradication success, and especially to avoid unnecessary antibiotic use.

Toxoplasma gondii: A possible etiologic agent for Alzheimer's disease

Toxoplasma gondii (T. gondii) is one of the most pervasive neurotropic pathogens causing different lesions in a wide variety of mammals as intermediate hosts, including humans. It is estimated that one-third of the world population is infected with T. gondii; however, for a long time, there has been much interest in the examination of the possible role of this parasite in the development of mental disorders, such as Alzheimer's disease (AD). T. gondii may play a role in the progression of AD using mechanisms, such as the induction of the host's immune responses, inflammation of the central nervous system (CNS), alteration in the levels of neurotransmitters, and activation of indoleamine-2,3-dyoxigenase. This paper presents an appraisal of the literature, reports, and studies that seek to the possible role of T. gondii in the development of AD. For achieving the purpose of the current study, a search of six English databases (PubMed, ScienceDirect, Web of Science, Scopus, ProQuest, and Google Scholar) was performed. The results support the involvement of T. gondii in the induction and development of AD. Indeed, T. gondii can be considered a risk factor for the development of AD and requires the special attention of specialists and patients. Furthermore, the results of this study may contribute to prevent or delay the progress of AD worldwide. Therefore, it is required to carry out further studies in order to better perceive the parasitic mechanisms in the progression of AD.

Multi-pathogen infections and Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease associated with the overproduction and accumulation of amyloid-β peptide and hyperphosphorylation of tau proteins in the brain. Despite extensive research on the amyloid-based mechanism of AD pathogenesis, the underlying cause of AD is not fully understood. No disease-modifying therapies currently exist, and numerous clinical trials have failed to demonstrate any benefits. The recent discovery that the amyloid-β peptide has antimicrobial activities supports the possibility of an infectious aetiology of AD and suggests that amyloid-β plaque formation might be induced by infection. AD patients have a weakened blood-brain barrier and immune system and are thus at elevated risk of microbial infections. Such infections can cause chronic neuroinflammation, production of the antimicrobial amyloid-β peptide, and neurodegeneration. Various pathogens, including viruses, bacteria, fungi, and parasites have been associated with AD. Most research in this area has focused on individual pathogens, with herpesviruses and periodontal bacteria being most frequently implicated. The purpose of this review is to highlight the potential role of multi-pathogen infections in AD. Recognition of the potential coexistence of multiple pathogens and biofilms in AD's aetiology may stimulate the development of novel approaches to its diagnosis and treatment. Multiple diagnostic tests could be applied simultaneously to detect major pathogens, followed by anti-microbial treatment using antiviral, antibacterial, antifungal, and anti-biofilm agents.

Helicobacter pylori, Vascular Risk Factors and Cognition in U.S. Older Adults

Previous studies suggested that Helicobacter pylori infection could be a risk factor for stroke, dementia, and Alzheimer's disease (AD). The authors examined data from participants, 60 years old and older in the Third National Health and Nutrition Examination Survey (NHANES-III) to assess the relation between Helicobacter pylori infection and results of the Mini-Mental State Examination (n = 1860) using logistic regression analysis controlling for age, gender, race/ethnicity, education, poverty and history of medically diagnosed diabetes. Moreover, we examined performance on the digit-symbol substitution test (DSST) of 1031 participants in the 1999-2000 NHANES according to their H. pylori infection status controlling for potential confounders using multiple linear regression analyses. In 1988-1991, older adults infected with CagA strains of H. pylori had a 50% borderline statistically significant increased level of cognitive impairment, as measured by low Mini-Mental State Examination (MMSE) scores (age-education adjusted prevalence ratio: 1.5; 95% confidence interval: 1.0, 2.0). In 1999-2000, older US adults infected with H. pylori scored 2.6 fewer points in the DSST than those uninfected (mean adjusted difference: -2.6; 95% confidence interval -5.1, -0.1). The authors concluded that H. pylori infection might be a risk factor for cognitive decline in the elderly. They also found that low cobalamin and elevated homocysteine were associated with cognitive impairment.

Helicobacter pylori seropositivity and its association with incident all-cause and Alzheimer's disease dementia in large national surveys

INTRODUCTION

Infectious agents were recently implicated in Alzheimer's disease (AD) and etiology of other dementias, notably Helicobacter pylori.

METHODS

We tested associations of H. pylori seropositivity with incident all-cause and AD dementia and with AD-related mortality among US adults in a retrospective cohort study. Data from the National Health and Nutrition Surveys III, phase 1 (1988-1991) and 1999-2000 linked with Medicare and National Death Index registries, were used (baseline age ≥45 y, follow-up to 2013, N_pooled = 5927).

RESULTS

A positive association between H. pylori seropositivity and AD mortality was found in men (hazard ratio_{adj, pooled} = 4.33, 95% confidence interval: 1.51-12.41, P = .006), which was replicated for incident AD and all-cause dementia, with hazard ratio_{adj, pooled} = 1.45 (95% confidence interval: 1.03-2.04, P = .035) and hazard ratio_{adj, III} = 1.44 (95% confidence interval: 1.05-1.98, P = .022), respectively. These associations were also positive among higher socioeconomic status groups.

DISCUSSION

In sum, H. pylori seropositivity's direct association with AD mortality, all-cause dementia, and AD dementia was restricted to men and to higher socioeconomic status groups.

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.

Helicobacter pylori moderates the association between 5-MTHF concentration and cognitive function in older adults

Objective

To explore potential interactions between folate-cycle factors and Helicobacter pylori seropositivity in the prediction of cognitive function.

Methods

We used data obtained from the 1999–2000 continuous National Health and Nutrition Examination Survey produced by the United States’ Centers for Disease Control and Prevention. Using Ordinary Least Squares regression, we tested for associations between multiple folate-cycle factors, Helicobacter pylori seropositivity, and cognitive function assessed by the digit symbol coding subtest of the Wechsler Adult Intelligence Scale-III. We then tested for interactions between each of the folate-cycle factors and Helicobacter pylori in the prediction of cognitive function.

Results

Although Helicobacter pylori seropositivity, 5-methyltetrahydrofolate, vitamin B-12, and homocysteine were not associated with performance on the digit symbol coding task, Helicobacter pylori seropositivity interacted with 5-methyltetrahydrofolate concentration to predict performance on the digit symbol coding task. The Helicobacter pylori seropositive group performed worse on the digit symbol coding task as 5-methyltetrahydrofolate concentration decreased.

Conclusion

The interaction between Helicobacter pylori seropositivity and reduced folate-cycle factor 5-methyltetrahydrofolate might impair aspects of cognitive function.

Apolipoprotein E4 is associated with improved cognitive function in Amazonian forager-horticulturalists with a high parasite burden

The apolipoprotein E4 (E4) allele is present worldwide, despite its associations with higher risk of cardiovascular morbidity, accelerated cognitive decline during aging, and Alzheimer's disease (AD). The E4 allele is especially prevalent in some tropical regions with a high parasite burden. Equatorial populations also face a potential dual burden of high E4 prevalence combined with parasitic infections that can also reduce cognitive performance. We examined the interactions of E4, parasite burden, and cognitive performance in a traditional, nonindustrialized population of Amazonian forager-horticulturalists (N = 372) to test whether E4 protects against cognitive decline in environments with a heavy pathogen burden. Contrary to observations in industrial populations, older adult E4 carriers with high parasite burdens either maintained or showed slight improvements in cognitive performance, whereas non-E4 carriers with a high parasite burden showed reduced cognitive performance. Being an E4 carrier is the strongest risk factor to date of AD and cognitive decline in industrial populations; it is associated with greater cognitive performance in individuals facing a high parasite and pathogen load, suggesting advantages to the E4 allele under certain environmental conditions. The current mismatch between postindustrial hygienic lifestyles and active parasite-rich environs may be critical for understanding genetic risk for cognitive aging.-Trumble, B. C., Stieglitz, J., Blackwell, A. D., Allayee, H., Beheim, B., Finch, C. E., Gurven, M., Kaplan, H. Apolipoprotein E4 is associated with improved cognitive function in Amazonian forager-horticulturalists with a high parasite burden.

Folate and Inflammatory Markers Moderate the Association Between Helicobacter pylori Exposure and Cognitive Function in US Adults

BACKGROUND

Helicobacter pylori (H. pylori) infection is associated with cognitive deficits in humans, an association potentially mediated or moderated by folate concentration or inflammation.

MATERIALS AND METHODS

We used the National Health and Nutrition Examination Survey (NHANES) datasets to examine whether folate concentration or inflammation mediates or moderates the relationship between H. pylori and cognitive function. Models were performed using linear, Poisson, and zero-inflated Poisson regression, and we performed separate analyses for groups aged 20-59 and 60-90 years with sample sizes ranging from 700 to 1700.

RESULTS

We did not find evidence of mediation in either age group. In the 20- to 59-year group, interactions between H. pylori and ferritin (p values ranging from .004 to .039) were associated with worse processing speed, better working memory, and worse reaction time. Interactions between H. pylori and fibrinogen (p values ranging from .023 to .045), C-reactive protein (CRP) (p = .023), and the inflammatory index (p = .045) were associated with worse processing speed. In 60- to 90-year-olds, H. pylori interacted with ferritin and the inflammatory index to predict fewer mathematical errors (p values of .036 and .023). Interactions with folate (p values of .016 and .006) and C-reactive protein (p values ranging from <.001 to .048) were inconsistent in directionality.

CONCLUSIONS

In this dataset, representative of the US population, inflammation and folate concentrations moderated but did not mediate the association between H. pylori seropositivity and cognition.

A Systematic Review and Meta-Analysis of the Association between Helicobacterpylori Infection and Dementia

BACKGROUND

A positive association between Helicobacter pylori infection and dementia has been reported, yet findings are inconsistent.

OBJECTIVE

To examine the association between H. pylori infection and dementia.

METHODS

A literature search was performed using the databases OVID-Medline, Institute of Scientific Information Web of Science, and EMBASE. The meta-analysis was conducted using the random effects model. The primary analysis included studies in which the exposure variable was presence of H. pylori infection (yes versus no) and the outcome was incident dementia (yes versus no), which was pre-selected as the end-result of gradual cognitive decline overtime. Publication bias was explored using funnel plot and the Egger regression intercept.

RESULTS

A total of 260 records were identified; 13 addressed cognition and/or dementia in relation to H. pylori infection, of which only seven were included in the meta-analysis. The primary analysis showed a significant positive association between H. pylori infection and dementia; pooled odds ratio 1.71 (95% CI 1.17-2.49) (pv = 0.01). No significant evidence of publication bias was found.

CONCLUSIONS

H. pylori may play a role in the etiology of dementia. Identification of the biological mechanisms of such association is needed, as well as assessment of the impact of H. pylori therapy on the risk and progression of dementia.

Infectious disease burden and cognitive function in young to middle-aged adults

Prior research has suggested an association between exposure to infectious disease and neurocognitive function in humans. While most of these studies have explored individual viral, bacterial, and even parasitic sources of infection, few have considered the potential neurocognitive burden associated with multiple infections. In this study, we utilized publically available data from a large dataset produced by the Centers for Disease Control and Prevention that included measures of neurocognitive function, sociodemographic variables, and serum antibody data for several infectious diseases. Specifically, immunoglobulin G antibodies for toxocariasis, toxoplasmosis, hepatitis A, hepatitis B, and hepatitis C, cytomegalovirus, and herpes 1 and 2 were available in 5662 subjects. We calculated an overall index of infectious-disease burden to determine if an aggregate measure of exposure to infectious disease would be associated with neurocognitive function in adults aged 20-59 years. The index predicted processing speed and learning and memory but not reaction time after controlling for age, sex, race-ethnicity, immigration status, education, and the poverty-to-income ratio. Interactions between the infectious-disease index and some sociodemographic variables were also associated with neurocognitive function. In summary, an index aggregating exposure to several infectious diseases was associated with neurocognitive function in young- to middle-aged adults.