Alzheimer’s disease and Helicobacter pylori infection: Defective immune regulation and apoptosis as proposed common links

Helicobacter pylori may be involved in cognitive impairment and dementia development through induction of atrophic gastritis, vitamin B-12–folate deficiency, and hyperhomocysteinemia sequence

“…Moreover, histologic multifocal chronic gastritis (body and antrum atrophy) was observed in the vast majority of our patients as compared with controls (6, 7). These patterns of H. pylori-related chronic gastritis have also been reported by others (7). Importantly, an increased serum Hcy concentration has been shown in our AD patients (7).…”

“…These patterns of H. pylori-related chronic gastritis have also been reported by others (7). Importantly, an increased serum Hcy concentration has been shown in our AD patients (7). Chronic gastritis, as a result of H. pylori infection, can lead to malabsorption of vitamins (B-12) and folate, which results in the failure of methylation by 5-methyl-tetrahydrofolic acid and, hence, in the accumulation of Hcy (7).…”

“…A higher seropositivity for anti-H. pylori immunoglobulin (Ig) G antibodies was reported in AD patients than in age-matched controls (5). However, this serologic test has limitations because it does not discriminate between current and old infections (7). Such a distinction is essential because current H. pylori infection induces humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mimicry), cross-react with components of nerves (7) and thereby affect or perpetuate neural tissue damage.…”

Alzheimer's Disease and Peripheral Infections: The Possible Contribution from Periodontal Infections, Model and Hypothesis

“…However, another study did not replicate this finding [35]. Higher serum IgG antibody against H. pylori has been reported in AD subjects compared to controls [56]. Spirochetes, identified by dark field microscopy, were reported present in blood, CSF and brain samples from 14 AD cases but were absent in 13 controls lacking symptoms of AD [78,79].…”

Alzheimer’s disease and gut microbiota

“…The eradication of H. pylori of AD patients can prolong AD survival, also potential suggesting that H. pylori infection may participate in the pathogenic process of AD (Kountouras et al, 2012). H. pylori infection may influence the pathophysiology of AD through releasing proinflammatory cytokines and inducing oxidative stress (Kountouras et al, 2007).…”