Abstract: Older adults who received at least one influenza vaccine were 40% less likely to develop Alzheimer’s disease during the four-year follow-up than their peers who did not receive the vaccine.
Source: UT Houston
People who received at least one flu vaccine were 40% less likely to develop Alzheimer’s disease over four years than their unvaccinated peers, a new study by UTHealth Houston found.
The research was led by first author Avram S. Bukhbinder, MD, a recent former McGovern Medical School student at UTHealth Houston, and senior author Paul. E. Schulz, MD, Rick McCord, professor of neurology at McGovern Medical School, compared the risk of Alzheimer’s disease incidence between patients with and without prior influenza vaccination in a large sample of adults in the U.S. aged 65 and older.
An early online version of the document detailing the findings is available prior to publication in the August 2 issue of the journal. Journal of Alzheimer’s Disease.
“We have found that influenza vaccination in the elderly reduces the risk of developing Alzheimer’s disease for several years. The strength of this protective effect increased with the number of years a person received the annual flu vaccine – in other words, the rate of Alzheimer’s disease was the lowest among those who consistently received the flu vaccine each year, ”said Bukhbinder, who is still part of Schulz’s research team while in his first year at the Department of Pediatric Neurology at Massachusetts General Hospital.
“Future research should assess whether influenza vaccination is also associated with a rate of symptom progression in patients who already have Alzheimer’s dementia.”
The study – which comes two years after UTHealth Houston researchers discovered a possible link between flu vaccines and a reduced risk of Alzheimer’s disease – analyzed a much larger sample than the previous study, including 935,887 flu-vaccinated patients and 935,887 unvaccinated patients.
During four-year follow-up, it was found that about 5.1% of flu-vaccinated patients developed Alzheimer’s disease. Meanwhile, 8.5% of unvaccinated patients developed Alzheimer’s disease during follow-up.
These results highlight the strong protective effect of influenza vaccines against Alzheimer’s disease, according to Bukhbinder and Schulz. However, the underlying mechanisms behind this process require further study.
“Since there is evidence that several vaccines can protect against Alzheimer’s disease, we think this is not a specific effect of the flu vaccine,” said Schulz, who is also a professor of neurodegenerative diseases in the Umphrey family and director of neurocognitive disorders. Center at McGovern Medical School.
“Instead, we believe that the immune system is complex and that some changes, such as pneumonia, can activate it in a way that exacerbates Alzheimer’s disease. But other things that activate the immune system can do it in a different way – one that protects against Alzheimer’s disease. It is clear that we have more to learn about how the immune system worsens or improves the outcomes of this disease. ”
Alzheimer’s disease affects more than 6 million people living in the United States, and the number of patients is growing due to an aging population. Past studies have found a reduced risk of dementia associated with previous exposure to various vaccinations in adulthood, including those against tetanus, polio, and herpes, in addition to the flu vaccine and others.
In addition, as more time passes since the introduction of the COVID-19 vaccine and longer monitoring data become available, Bukhbinder said it would be worth exploring whether there is a similar association between COVID-19 vaccination and the risk of Alzheimer’s disease.
About this vaccination and news about Alzheimer’s disease research
Original research: Open access.
“Risk of Alzheimer’s disease after influenza vaccination: a cohort of claims-based cohort using pairing of propensity scores”By Avram S. Bukhbinder et al. Journal of Alzheimer’s Disease
Risk of Alzheimer’s disease after influenza vaccination: a cohort of claims-based cohort using pairing of propensity scores
Previous studies have found a reduced risk of dementia of any etiology following influenza vaccination in selected populations, including veterans and patients with severe chronic health conditions. However, the effect of influenza vaccination on the risk of Alzheimer’s disease (AD) in the general group of elderly adults in the United States has not been characterized.
Compare the risk of AD incidents between patients with and without prior influenza vaccination in a large database of claims in the United States.
Data on identified claims from 1 September 2009 to 31 August 2019 were used. Eligible patients were without dementia during the 6-year review period and ≥65 years until the start of follow-up. Matching preferences and scores (PSM) were used to create groups of vaccinated and unvaccinated against influenza with similar baseline demographics, drug use, and comorbidities. Relative risk (RR) and absolute risk reduction (ARR) were assessed to assess the effect of influenza vaccination on AD risk during the 4-year follow-up.
From an incomparable sample of eligible patients (n= 2,356,479), PSM produced a sample of 935,887 pairs vaccinated against influenza and unvaccinated. The harmonized sample was 73.7 (SD, 8.7) years and 56.9% women, with a median follow-up of 46 (IQR, 29–48) months; 5.1% (n= 47,889) vaccinated against influenza and 8.5%n= 79 630) patients not vaccinated against influenza developed AD during follow-up. The RR was 0.60 (95% CI, 0.59–0.61) and the ARR was 0.034 (95% CI, 0.033–0.035), corresponding to the number required for treatment of 29.4.
This study shows that influenza vaccination is associated with a reduced risk of AD in a national sample of adults in the U.S. aged 65 and over.
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