Vaccines and Dementia: Part II. Efficacy of BCG and Other Vaccines Against Dementia

Lower risk of dementia with AS01-adjuvanted vaccination against shingles and respiratory syncytial virus infections

AS01-adjuvanted shingles (herpes zoster) vaccination is associated with a lower risk of dementia, but the underlying mechanisms are unclear. In propensity-score matched cohort studies with 436,788 individuals, both the AS01-adjuvanted shingles and respiratory syncytial virus (RSV) vaccines, individually or combined, were associated with reduced 18-month risk of dementia. No difference was observed between the two AS01-adjuvanted vaccines, suggesting that the AS01 adjuvant itself plays a direct role in lowering dementia risk.

Infections, genetics, and Alzheimer's disease: Exploring the pathogenic factors for innovative therapies

Alzheimer's disease (AD) is a progressive neurodegenerative condition that creates a significant global health challenge and profoundly affects patients and their families. Recent research has highlighted the critical role of microorganisms, particularly viral infections, in the pathogenesis of AD. The involvement of viral infections in AD pathogenesis is predominantly attributed to their ability to induce neuroinflammation and amyloid beta (Aβ) deposition in the brain. The extant research exploring the relationship between viruses and AD has focused largely on Herpesviridae family. Traces of Herpesviruses, such as Herpes Simplex Virus-1 and Epstein Barr Virus, have been found in the brains of patients with AD. These viruses are thought to contribute to the disease progression by triggering chronic inflammatory responses in the brain. They can remain dormant in the brain, and become reactivated due to stress, a secondary viral infection, or immune-senescence in older adults. This review focuses on the association between Herpesviridae and bacterial infections with AD. We explore the genetic factors that might regulate viral illness and discuss clinical trials investigating antiviral and anti-inflammatory agents as possible therapeutic strategies to mitigate cognitive decline in patients with AD. In summary, understanding the interplay between infections, genetic factors, and AD pathogenesis may pave the way for novel therapeutic approaches, facilitating better management and possibly even prevent this debilitating disease.

Recombinant zoster vaccine and the risk of dementia

BACKGROUND

Herpes zoster is a potential risk factor for dementia. The effectiveness of the recombinant zoster vaccine for preventing dementia is uncertain.

METHODS

This retrospective cohort study used de-identified claims data from the Optum Labs Data Warehouse database from January 1, 2017, to December 31, 2022, to determine whether the recombinant zoster vaccine is associated with a reduced risk of dementia. Immunocompetent patients with ≥365 days of continuous enrollment were included, with the risk period starting upon age-eligibility for the recombinant zoster vaccination. Cox regression adjusted for time-fixed and time-updated measures every six months was implemented to estimate hazard ratios for dementia. Herpes zoster diagnosis and antiviral therapy were also assessed.

RESULTS

There were 4,502,678 individuals (median [IQR] age, 62 [54-71] years; 51 % female) included in this study: 206,297 (4.6 %) were partially vaccinated, and 460,413 (10.2 %) were fully vaccinated. The incidence rate of dementia was 99.1 cases per 10,000 person-years in the fully vaccinated group, 108.2 cases per 10,000 person-years in the partially vaccinated group, and 135.0 cases per 10,000 person-years in the unvaccinated group. After adjustment, vaccination was significantly associated with a decreased risk of dementia for two doses (hazard ratio (HR): 0.68; 95 % CI: 0.67-0.70; P < .001) and for one dose (HR 0.89; 95 % CI: 0.87-0.92; P < .001). Having a herpes zoster diagnosis before the first vaccination dose was associated with an increased hazard of dementia (HR 1.47; 95 % CI: 1.42-1.52; P < .001) compared to those with no diagnosis. Antivirals used to treat zoster infection were protective against dementia (HR 0.42; 95 % CI: 0.40-0.44; P < .001).

CONCLUSIONS

These findings suggest that the recombinant zoster vaccine is associated with a decreased risk of dementia and highlight an additional benefit of vaccination beyond preventing herpes zoster.

Relationships between bacteria and the mucus layer

The mucus layer on epithelial cells is an essential barrier, as well as a nutrient-rich niche for bacteria, forming a dynamic, functional and symbiotic ecosystem and first line of defense against invading pathogens. Particularly bacteria in biofilms are very difficult to eradicate. The extensively O-glycosylated mucins are the main glycoproteins in mucus that interact with microbes. For example, mucins act as adhesion receptors and nutritional substrates for gut bacteria. Mucins also play important roles in immune responses, and they control the composition of the microbiome, primarily due to the abundance of complex O-glycans. In inflammation or infection, the structures of mucin O-glycans can change and thus affect mucin function, impact biofilm formation and the induction of virulence pathways in bacteria. In turn, bacteria can support host cell growth, mucin production and can stimulate changes in the host immune system and responses leading to healthy tissue function. The external polysaccharides of bacteria are critical for controlling adhesion and biofilm formation. It is therefore important to understand the relationships between the mucus layer and microbes, the mechanisms and regulation of the biosynthesis of mucins, of bacterial surface polysaccharides, and adhesins. This knowledge can provide biomarkers, vaccines and help to develop new approaches for improved therapies, including antibiotic treatments.

A Risk Management Approach to Global Pandemics of Infectious Disease and Anti-Microbial Resistance

Pandemics of infectious disease and growing anti-microbial resistance (AMR) pose major threats to global health, trade, and security. Conflict and climate change compound and accelerate these threats. The One Health approach recognizes the interconnectedness of human, animal, and environmental health, but is grounded in the biomedical model, which reduces health to the absence of disease. Biomedical responses are insufficient to meet the challenges. The COVID-19 pandemic is the most recent example of the failure of this biomedical model to address global threats, the limitations of laboratory-based surveillance, and the exclusive focus on vaccination for disease control. This paper examines the current paradigm through the lens of polio and the global campaign to eradicate it, as well as other infectious threats including mpox and drug-resistant tuberculosis, particularly in the context of armed conflict. Decades before vaccines became widely available, public health measures-ventilation, chlorination, nutrition and sanitation- led to longer, healthier, and even taller lives. Chlorine, our primary tool of public health, conquered cholera and transformed infection control in hospitals. The World Health Organization (WHO), part of the One Health alliance, focuses mainly on antibiotics and vaccines to reduce deaths due to superbugs and largely ignores the critical role of chlorine to control water-borne diseases (including polio) and other infections. Moreover, the One Health approach ignores armed conflict. Contemporary wars are characterized by indiscriminate bombing of civilians, attacks targeting healthcare, mass displacement and lack of humanitarian access, conditions which drive polio outbreaks and incubate superbugs. We discuss the growing trend of attacks on healthcare and differentiate between types: community-driven attacks targeting vaccinators in regions like Pakistan, and state-sponsored attacks by governments such as those of Syria and Russia that weaponize healthcare to deliberately harm whole populations. Both fuel outbreaks of disease. These distinct motivations necessitate tailored responses, yet the WHO aggregates these attacks in a manner that hampers effective intervention. While antimicrobial resistance is predictable, the escalating pandemic is the consequence of our reliance on antibiotics and commitment to a biomedical model that now borders on pathological. Our analysis reveals the international indenture to the biomedical model as the basis of disease control is the root driver of AMR and vaccine-derived polio. The unique power of vaccines is reduced by vaccination-only strategy, and in fact breeds vaccine-derived polio. The non-specific effects of vaccines must be leveraged, and universal vaccination must be supplemented by international investment in water chlorination. This will reduce health costs and strengthen global health security. While vaccines are an important weapon to combat pandemics and AMR, they must be accompanied by the entire arsenal of public health interventions

Vaccines and Dementia: Part I. Non-Specific Immune Boosting with BCG: History, Ligands, and Receptors

Vaccines such as Bacille Calmette-Guérin (BCG) can apparently defer dementia onset with an efficacy better than all drugs known to date, as initially reported by Gofrit et al. (PLoS One14, e0224433), now confirmed by other studies. Understanding how and why is of immense importance because it could represent a sea-change in how we manage patients with mild cognitive impairment through to dementia. Given that infection and/or inflammation are likely to contribute to the development of dementias such as Alzheimer's disease (Part II of this work), we provide a historical and molecular background to how vaccines, adjuvants, and their component molecules can elicit broad-spectrum protective effects against diverse agents. We review early studies in which poxvirus, herpes virus, and tuberculosis (TB) infections afford cross-protection against unrelated pathogens, a concept known as 'trained immunity'. We then focus on the attenuated TB vaccine, BCG, that was introduced to protect against the causative agent of TB, Mycobacterium tuberculosis. We trace the development of BCG in the 1920 s through to the discovery, by Freund and McDermott in the 1940 s, that extracts of mycobacteria can themselves exert potent immunostimulating (adjuvant) activity; Freund's complete adjuvant based on mycobacteria remains the most potent immunopotentiator reported to date. We then discuss whether the beneficial effects of BCG require long-term persistence of live bacteria, before focusing on the specific mycobacterial molecules, notably muramyl dipeptides, that mediate immunopotentiation, as well as the receptors involved. Part II addresses evidence that immunopotentiation by BCG and other vaccines can protect against dementia development.

Intravesical Bacille Calmette-Guerin (BCG) Vaccine Affects Cognition

The Montreal Cognitive Assessment (MoCA) is a valuable assessment of the patient's awareness of time and place. We show that bacille Calmette-Guerin (BCG) significantly affects MoCA testing when administered by the intravesical route. MoCA scores were lower with increasing age and higher in more formally educated individuals. Patients receiving BCG tended to maintain their MoCA scores, whereas almost half the control cases tended to show reduced scores. This benefit is supported by reduced pre-amyloid biomarkers in BCG-injected healthy volunteers and a favorable effect on neuronal dendritic development in animal models. Our results suggest that BCG has a beneficial impact on the cognitive status of older individuals.