Association between Helicobacter pylori infection and cognitive impairment in the elderly

Association between oral health and cognitive impairment in older adults: Insights from a Six-year prospective cohort study

OBJECTIVE

This study aims to investigate the relationships between four baseline oral conditions (periodontal status, dental caries, tooth wear, and dentition) and repeated global cognition or domain-specific cognition (memory, executive function, attention, and verbal fluency) in non-demented older adults over time.

METHODS

This prospective cohort study (2011-2019) enrolled 516 non-demented community-dwelling older adults (age ≥ 65) to explore the association between oral health and cognitive function. Global and domain-specific cognition were assessed biennially (four repeats) using a battery of neuropsychological tests. The baseline oral health conditions were examined, including periodontal status, dental caries, tooth wear, and dentition. The association of these oral conditions with cognition was evaluated by generalized linear mixed models. Stratified analyses were performed by important covariates.

RESULTS

Over time, dental caries was associated with poor memory in two different logical memory tests (β^= -0.06 and β^= -0.04). Incomplete dentition with less than 28 teeth was associated with poor performance in attention (β^= -0.05) and verbal fluency (β^= -0.03). These associations became more evident in those with an elevated inflammatory marker (IL-6, β^= -0.11 to -0.08). In contrast, tooth wear was associated with better memory in two different logical memory tests (β^= 0.33 and β^= 0.36) and better executive function (β^= 0.06) over time, and this association became more evident in those with the lowest inflammatory marker (IL-6, β^= 0.10).

CONCLUSIONS

Dental caries and incomplete dentition were associated with poor memory, attention, and verbal fluency performance. Conversely, tooth wear was associated with better memory performance and executive function.

CLINICAL SIGNIFICANCE

For early prevention of dementia, an evaluation of multiple dental and periodontal status in older adults helps predict the risk of dementia in the preclinical phase. Maintaining intact tooth structure without caries progression and eventually tooth loss may help prevent the worsening of memory, attention, and verbal fluency over time.

Oral administration of bacterial probiotics improves Helicobacter pylori-induced memory impairment in rats: Insights from behavioral and biochemical investigations

There are numerous evidence supporting the association between Helicobacter pylori (H. pylori) infection and the occurrence of cognitive deficits in humans. In this regard, treatment of H. pylori infection has been suggested as an effective strategy to decelerate the neurodegenerative processes of memory deficits in AD patients. Numerous studies support the beneficial effects of probiotics on various pathological conditions, particularly cognitive deficits, however, this concern has not been addressed in relation to the memory impairment induced by H. pylori infection. In the present study, we aimed to reveal whether oral administration of two bacterial probiotics (including Lactobacillus rhamnosus and Lactobacillus plantarum), could ameliorate H. pylori-induced memory deficits at behavioral level in rats. Besides, cellular mechanisms were investigated by biochemical methods to find out how probiotic effects are mediated in hippocampal circuitry. Male Wistar rats were infected by H. pylori for 3 consecutive days, then probiotic treatment was done for the next 3 days and after a drug-free period (12 days), animals were assessed by Morris Water Maze and Novel Object Recognition tests. Finally, rats were euthanized by CO2 and hippocampal tissues were excised for biochemical measurements. Results indicated that H. pylori infection markedly impairs memory function in rats which is associated with alterations of oxidative, inflammatory, neurotrophic, and cholinergic markers. Interestingly, treatment with either of the probiotics alone or in combination, significantly improved the H. pylori-induced memory deficits and this was associated with restoration of balance in biochemical factors within the hippocampal neurons.

Association between Helicobacter pylori infection and incident risk of dementia: The AMI cohort

BACKGROUND

Chronic infectious diseases are increasingly being considered as potential contributors to dementia risk. Among those infections, Helicobacter pylori, the main cause of chronic gastritis worldwide, has been suggested. As the prevalence of H. pylori infection has decreased, the main objective of this work was to reconsider the association between H. pylori infection and the risk of incident dementia, including Alzheimer's disease.

METHODS

Prospective cohort of 689 older (≥65 years) agricultural workers from Southwest France. Descriptive and comparative analyses were performed according to H. pylori status determined by serology at baseline. The risk of incident dementia according to H. pylori status over a 7-year follow-up was explored by survival analyses: Kaplan-Meier curve and Cox proportional hazards models.

RESULTS

Two-hundred (29.0%) participants were H. pylori-positive at baseline. Compared to H. pylori-negative participants, they showed worse cognitive performances at baseline. Eighty-five incident dementia cases were diagnosed during the follow-up period. After adjustment for age, sex, education, apolipoprotein ε4, and several cardiovascular risk factors, H. pylori remained associated with an increased risk of dementia (HR 1.70, 95% CI, 1.05-2.74). The risk was stronger for Alzheimer's disease (HR 2.85, 95% CI, 1.58-5.12).

CONCLUSIONS

Despite an observed decrease in H. pylori infection prevalence, this study provides evidence for the association between H. pylori infection and dementia. These results should encourage further research on the mechanisms underlying the contribution of infectious diseases to pathological brain aging, especially the influence of gut inflammation on the brain.

Value of serum brain-derived neurotrophic factor and glial fibrillary acidic protein for detecting depression in patients with Helicobacter pylori infection

OBJECTIVE

Infection with helicobacter pylori (H. pylori) is associated with depression, and depression can affect the outcome of H. pylori treatment. This study aimed to evaluate the value of serum brain-derived neurotrophic factor (BDNF) and glial fibrillary acidic protein (GFAP) for predicting depression in H. pylori-positive patients.

METHOD

A total of 82H. pylori-positive and 82H. pylori-negative patients were recruited for this study. All patients underwent neuropsychological and gastrointestinal assessments and blood sampling. BDNF and GFAP levels were measured in serum. The least absolute shrinkage and selection operator (LASSO) model was used to determine a composite marker.

RESULTS

H. pylori-positive patients showed significantly increased serum GFAP levels and significantly decreased serum BDNF levels compared to H. pylori-negative patients. Among H. pylori-positive patients, serum levels of gastrin 17 (G-17), pepsinogen (PG) I/PGII, BDNF, and GFAP, as well as Gastrointestinal Symptom Rating Scale (GSRS) scores, were significantly correlated with Hamilton Depression Scale (HAMD-24) overall scores and factor scores. Interactions between serum BDNF/GFAP and gastrointestinal serum indices or GSRS scores were significantly associated with HAMD-24 scores in H. pylori-positive patients. The LASSO model indicated that the combination of serum BDNF, GFAP, and G-17 and GSRS scores could identify H. pylori-positive patients with depression with an area under the curve of 0.879.

CONCLUSION

Circulating changes in BDNF and GFAP were associated with the occurrence of depression in H. pylori-positive patients. A composite marker including neural and gastrointestinal function-related indices may be of value for identifying depression among H. pylori-positive patients.

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.

Controlling the Impact of Helicobacter pylori-Related Hyperhomocysteinemia on Neurodegeneration

Helicobacter pylori infection consists a high global burden affecting more than 50% of the world’s population. It is implicated, beyond substantiated local gastric pathologies, i.e., peptic ulcers and gastric cancer, in the pathophysiology of several neurodegenerative disorders, mainly by inducing hyperhomocysteinemia-related brain cortical thinning (BCT). BCT has been advocated as a possible biomarker associated with neurodegenerative central nervous system disorders such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and/or glaucoma, termed as “ocular Alzheimer’s disease”. According to the infection hypothesis in relation to neurodegeneration, Helicobacter pylori as non-commensal gut microbiome has been advocated as trigger and/or mediator of neurodegenerative diseases, such as the development of Alzheimer’s disease. Among others, Helicobacter pylori-related inflammatory mediators, defensins, autophagy, vitamin D, dietary factors, role of probiotics, and some pathogenetic considerations including relevant involved genes are discussed within this opinion article. In conclusion, by controlling the impact of Helicobacter pylori-related hyperhomocysteinemia on neurodegenerative disorders might offer benefits, and additional research is warranted to clarify this crucial topic currently representing a major worldwide burden.

Helicobacter pylori Infection Is Associated with Long-Term Cognitive Decline in Older Adults: A Two-Year Follow-Up Study

BACKGROUND

Previous cross-sectional studies have identified a possible link between Helicobacter pylori (H. pylori) infection and dementia. However, the association of H. pylori infection with longitudinal cognitive decline has rarely been investigated.

OBJECTIVE

This cohort study aims to demonstrate the effects of H. pylori infection on longitudinal cognitive decline.

METHODS

This cohort study recruited 268 subjects with memory complaints. Among these subjects, 72 had a history of H. pylori infection, and the rest 196 subjects had no H. pylori infection. These subjects were followed up for 24 months and received cognitive assessment in fixed intervals of 12 months.

RESULTS

At baseline, H. pylori infected, and uninfected participants had no difference in MMSE scores. At 2 years of follow-up, H. pylori infected participants had lower MMSE scores than uninfected participants. H. pylori infection was associated with an increased risk of longitudinal cognitive decline, as defined by a decrease of MMSE of 3 points or more during follow-up, adjusting for age, sex, education, APOEɛ4 genotype, hypertension, diabetes, hyperlipidemia, and smoking history (HR: 2.701; 95% CI: 1.392 to 5.242). H. pylori infection was associated with larger cognitive decline during follow-up, adjusting for the above covariates (standardized coefficient: 0.282, p < 0.001). Furthermore, H. pylori infected subjects had significantly higher speed of cognitive decline than uninfected subjects during follow-up, adjusting for the above covariates.

CONCLUSION

H. pylori infection increases the risk of longitudinal cognitive decline in older subjects with memory complaints. This study is helpful for further understanding the association between infection and dementia.

Contribution of preoperative gut microbiota in postoperative neurocognitive dysfunction in elderly patients undergoing orthopedic surgery

Objective

To investigate the role of gut microbiota and metabolites in POCD in elderly orthopedic patients, and screen the preoperative diagnostic indicators of gut microbiota in elderly POCD.

Method

40 elderly patients undergoing orthopedic surgery were enrolled and divided into Control group and POCD group following neuropsychological assessments. Gut microbiota was determined by 16S rRNA MiSeq sequencing, and metabolomics of GC-MS and LC-MS was used to screen the differential metabolites. We then analyzed the pathways enriched by metabolites.

Result

There was no difference in alpha or beta diversity between Control group and POCD group. There were significant differences in 39 ASV and 20 genera bacterium in the relative abundance. Significant diagnostic efficiency analyzed by the ROC curves were found in 6 genera bacterium. Differential metabolites in the two groups including acetic acid, arachidic acid, pyrophosphate etc. were screened out and enriched to certain metabolic pathways which impacted the cognition function profoundly.

Conclusion

Gut microbiota disorders exist preoperatively in the elderly POCD patients, by which there could be a chance to predict the susceptible population.

Clinical Trial Registration

[http://www.chictr.org.cn/edit.aspx?pid=133843&htm=4], identifier [ChiCTR2100051162].

Relationship of Cognition and Alzheimer's Disease with Gastrointestinal Tract Disorders: A Large-Scale Genetic Overlap and Mendelian Randomisation Analysis

Emerging observational evidence suggests links between cognitive impairment and a range of gastrointestinal tract (GIT) disorders; however, the mechanisms underlying their relationships remain unclear. Leveraging large-scale genome-wide association studies’ summary statistics, we comprehensively assessed genetic overlap and potential causality of cognitive traits and Alzheimer’s disease (AD) with several GIT disorders. We demonstrate a strong and highly significant inverse global genetic correlation between cognitive traits and GIT disorders—peptic ulcer disease (PUD), gastritis-duodenitis, diverticulosis, irritable bowel syndrome, and gastroesophageal reflux disease (GERD), but not inflammatory bowel disease (IBD). Further analysis detects 35 significant (p < 4.37 × 10−5) bivariate local genetic correlations between cognitive traits, AD, and GIT disorders (including IBD). Mendelian randomisation analysis suggests a risk-decreasing causality of educational attainment, intelligence, and other cognitive traits on PUD and GERD, but not IBD, and a putative association of GERD with cognitive function decline. Gene-based analysis reveals a significant gene-level genetic overlap of cognitive traits with AD and GIT disorders (IBD inclusive, pbinomial-test = 1.18 × 10−3−2.20 × 10−16). Our study supports the protective roles of genetically-influenced educational attainments and other cognitive traits on the risk of GIT disorders and highlights a putative association of GERD with cognitive function decline. Findings from local genetic correlation analysis provide novel insights, indicating that the relationship of IBD with cognitive traits (and AD) will depend largely on their local effects across the genome.

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.

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.

Helicobacter and the Potential Role in Neurological Disorders: There Is More Than Helicobacter pylori

Trillions of symbiotic microbial cells colonize our body, of which the larger part is present in the human gut. These microbes play an essential role in our health and a shift in the microbiome is linked to several diseases. Recent studies also suggest a link between changes in gut microbiota and neurological disorders. Gut microbiota can communicate with the brain via several routes, together called the microbiome–gut–brain axis: the neuronal route, the endocrine route, the metabolic route and the immunological route. Helicobacter is a genus of Gram-negative bacteria colonizing the stomach, intestine and liver. Several papers show the role of H. pylori in the development and progression of neurological disorders, while hardly anything is known about other Helicobacter species and the brain. We recently reported a high prevalence of H. suis in patients with Parkinson’s disease and showed an effect of a gastric H. suis infection on the mouse brain homeostasis. Here, we discuss the potential role of H. suis in neurological disorders and how it may affect the brain via the microbiome–gut–brain axis.

Association between Helicobacter pylori infection and the risk of colorectal cancer: A systematic review and meta-analysis

BACKGROUND

The existing evidence on the relationship between Helicobacter pylori infection and the risk of colorectal cancer is inconsistent. We conducted a systematic review with a meta-analysis to explore this relationship and to determine whether the relationship varies according to the study characteristics.

METHODS

We searched the PubMed, OVID, EMBASE database, and the reference lists of pertinent articles published up to October 2019 by 2 researchers independently. Summary odds ratios (OR) with their 95% confidence intervals (CIs) were estimated using a random-effects model.

RESULTS

Forty seven studies including 17,416 cases of colorectal cancer (CRC) and 55,811 cases of control were included. Overall, H. pylori infection was associated with an increased risk of CRC (OR = 1.70 95% CI 1.64-1.76, I = 97%), although there was significant heterogeneity among the studies. Subgroup analysis revealed that the positive correlation might vary by the design of study conducted.

CONCLUSION

This meta-analysis demonstrates a positive association between H. pylori infection and the risk of colorectal cancer.

Gastrointestinal Tract Disorders in Older Age

Considering an increase in the life expectancy leading to a rise in the elderly population, it is important to recognize the changes that occur along the process of aging. Gastrointestinal (GI) changes in the elderly are common, and despite some GI disorders being more prevalent in the elderly, there is no GI disease that is limited to this age group. While some changes associated with aging GI system are physiologic, others are pathological and particularly more prevalent among those above age 65 years. This article reviews the most important GI disorders in the elderly that clinicians encounter on a daily basis. We highlight age-related changes of the oral cavity, esophagus, stomach, small and large bowels, and the clinical implications of these changes. We review epidemiology and pathophysiology of common diseases, especially as they relate to clinical manifestation in elderly. Details regarding management of specific disease are discussed in detail if they significantly differ from the management for younger groups or if they are associated with significant challenges due to side effects or polypharmacy. Cancers of GI tract are not included in the scope of this article.

Helicobacter pylori and extragastric diseases

Many studies have been performed in the last year concerning the potential role of Helicobacter pylori in different extragastric diseases, reinforcing the idea that specific microorganisms may cause diseases even far from the primary site of infection. While the role of H. pylori on idiopathic thrombocytopenic purpura, sideropenic anemia, and vitamin B12 deficiency has been well established, there is a growing interest in other conditions, such as cardiovascular, neurologic, dermatologic, obstetric, immunologic, and metabolic diseases. Concerning neurologic diseases, there is a great interest in cognitive impairment and neurodegeneration. The aim of this review was to summarize the results of the most relevant studies published over the last year on this fascinating topic.