Influenza Vaccination Associated with a 40% Reduced Risk of Alzheimer's Disease

Researchers here note a sizable reduction in Alzheimer's disease risk in that part of the aged population that receives influenza vaccines. There is the usual question as to whether vaccination is a proxy for conscientiousness in health matters throughout later life, but here the focus is on biological mechanisms that might explain the effect. The most plausible to my eyes is the phenomenon of trained immunity, in which vaccination for a specific pathogen can provoke a general improvement in all functions of the innate immune system. This improvement includes reduced inflammation, and the chronic inflammation of aging is clearly important in the onset and progression of neurodegenerative conditions.

This retrospective cohort study revealed that in adults aged 65 or old without dementia, mild cognitive impairment, or encephalopathy, patients who received at least one influenza vaccine were 40% less likely than their non-vaccinated peers to develop incident Alzheimer's disease (AD) during the 4-year follow-up period. The mechanisms underlying the apparent protective effects of influenza vaccination on AD risk merit further investigation. These mechanisms - and those underlying the effects of adulthood vaccinations on all-cause dementia risk in general - can be grouped into at least three broad, non-exclusive categories: 1) influenza-specific mechanisms, including mitigation of damage secondary to influenza infection and/or epitopic similarity between influenza proteins and AD pathology; 2) non-influenza-specific training of the innate immune system; and 3) non-influenza-specific changes in adaptive immunity via lymphocyte-mediated cross-reactivity.

The apparent effect of influenza vaccination on AD risk may be secondary to influenza-specific immunity conferred by the vaccine. Central nervous system (CNS) injury during influenza infection can occur from direct viral invasion of nervous tissues or as collateral damage from the systemic immune response to peripheral infection. An association between flu infection and AD risk is supported by mouse studies demonstrating that peripheral infection of wild-type mice with non-neurotropic influenza strains induces excessive microglial activation and subsequent alteration of neuronal morphology, particularly in the hippocampus, that persists after infection resolution.

Long-term, non-influenza-specific alteration of the innate immune system presents another class of mechanisms potentially underlying influenza vaccination's apparent effect on AD risk. Several vaccines, including the influenza vaccine, are associated with non-specific protective effects via long-term reprogramming of innate immune cells, a process termed "trained immunity". Several studies have shown that the innate-related changes in peripheral cytokines associated with vaccination can directly affect microglial activity, including the efficiency of microglia in clearing amyloid-β aggregates. Another mechanism related to innate immunity that potentially underlies the association between flu vaccination and AD is alteration of the sustained low-grade systemic elevation of proinflammatory cytokines referred to as "inflammaging" that is commonly observed among older adults.



If the flu vaccine has such a dramatic effect I wonder what sort of results we could get by eliminating latent cytomegalovirus infections.

Posted by: Matt at July 1st, 2022 10:57 AM

So this vaccin dosent contain alumium like all the rest?
alzhimers is alumium toxticity, so its pretty ironic to create a vaccin for it ..

Posted by: matthew at July 1st, 2022 11:17 AM

@Matt if you were not already aware, you may be pleased to know that Moderna has a CMV vaccine in the pipeline. It's indicated for pregnant women to avoid birth defects associated with acute CMV infection, but perhaps it could be used for the very purpose you suggested? At the very least, could vaccinate everyone who is not yet exposed.

Posted by: Will at July 1st, 2022 2:48 PM

This is not surprising. The flu, covid, and other viral diseases cause senescent cell development which accelerates aging. Vaccination might help partially prevent the creation of SnCs by getting rid of the infection faster or help the immune system get rid of more of the virus-caused SnCs.

Posted by: Florin at July 1st, 2022 6:40 PM

The Average American diet provides about 10mg of aluminum per day. The flue vaccine provides .2 mg. Nevertheless it's added because it works. Scientists aren't sure why. One theory is that the toxicity of aluminium salts is, paradoxically, the reason they work. They lead distressed cells to release uric acid, which activates an immune reaction normally associated with damage. Immune cells flock to the site, and start producing antibodies - and voila, the vaccine has worked.

That said the new Covid MNRA vaccines don't have any added aluminum at all because they don't need it. Wonder if they would be similar in a study like this.

Posted by: August33 at July 1st, 2022 8:52 PM

@All: It was only recently I became aware of the aluminium problem in food. We have to to all we can together as as society to eliminate it from all food packaging. Do we have to wait to we have nanomaterials like carbon? Cant we replace some Al with paper, etc.

Posted by: ciclo at July 2nd, 2022 11:47 AM

@Will: The best thing about vaccine for CMV is that I can have unprotected sex. Only waiting for the non-hormonal male p-pill. After that only bacteria that has to be eradicated. I has angered me over the years that progress have been slow in these areas including aging. Maybe it has to be the older generations from 1910, 1920, 1930, who are now mostly dead were if not opposing it reluctant to it. When I grow up there were some old people against condoms.

Posted by: Gekki at July 2nd, 2022 12:01 PM

It made me laugh. It is understandable that if they die early, they will not live to develop Alzheimer's disease.

Posted by: Omasta at July 3rd, 2022 3:31 AM

You stated: "It made me laugh. It is understandable that if they die early, they will not live to develop Alzheimer's disease."

I have never had the flu vaccine, but I would consider it. Do you have any info that those that receive the flu vaccine die early. I found some info that may indicate the opposite. That is, that those receive the flu vaccine live longer.

Of course, it could be that recipients of the vaccine are more likely to receive medical care / pharmaceuticals in general, and perhaps, that's why they have a reduced risk of an earlier death.

"In a meta-analysis of 4 randomized controlled trials and 12 observational studies, influenza vaccination was associated with 25% and 18% relative risk reduction in all-cause and cardiovascular mortality, respectively, in patients with cardiovascular disease."

Yedlapati SH, Khan SU, Talluri S, Lone AN, Khan MZ, Khan MS, Navar AM, Gulati M, Johnson H, Baum S, Michos ED. Effects of Influenza Vaccine on Mortality and Cardiovascular Outcomes in Patients With Cardiovascular Disease: A Systematic Review and Meta-Analysis. J Am Heart Assoc. 2021

"Influenza vaccination was significantly associated with reduced risks of death from all-causes, cardiovascular causes, and AMI/stroke in patients with hypertension. Influenza vaccination might improve outcome in hypertension."

Modin D, Claggett B, Jørgensen ME, Køber L, Benfield T, Schou M, Jensen JS, Solomon SD, Trebbien R, Fralick M, Vardeny O, Pfeffer MA, Torp-Pedersen C, Gislason G, Biering-Sørensen T. Flu Vaccine and Mortality in Hypertension: A Nationwide Cohort Study. J Am Heart Assoc. 2022 Mar 15;11(6):e021715. doi: 10.1161/JAHA.121.021715. Epub 2022 Feb 8. PMID: 35132866; PMCID: PMC9075279.

Posted by: Brad at July 4th, 2022 12:12 PM
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