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Summary: Older adults who had received at least one flu shot were 40% less likely to develop Alzheimer’s disease over four years of follow-up than their unvaccinated peers.
Source: UT Houston
According to a new study by UTHealth Houston, people who received at least one influenza vaccine were 40% less likely to develop Alzheimer’s over the course of four years than their unvaccinated peers.
The research was led by first author Avram S. Bukhbinder, MD, a recent graduate of McGovern Medical School at UTHealth Houston, and senior author Paul. E. Schulz, MD, Rick McCord Professor of Neurology at McGovern Medical School, compared the risk of developing Alzheimer’s disease between patients with and without prior flu vaccination in a large nationwide sample of US adults age 65 and older.
An early online version of the paper detailing the findings is available ahead of its publication in the August 2 issue Journal of Alzheimer’s Disease.
“We found that getting the flu shot in older adults reduced 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 an annual flu shot – in other words, the rate of developing Alzheimer’s was lowest among those who received the flu shot consistently every year,” Buchbinder said. who still is part of Schulz’s research team during his first year as a resident in the Department of Pediatric Neurology at Massachusetts General Hospital.
“Future research should examine whether influenza vaccination is also associated with the rate of symptom progression in patients who already have Alzheimer’s dementia.”
The study, which came two years after researchers from UTHealth Houston found a possible link between the flu vaccine and a reduced risk of Alzheimer’s, analyzed a much larger sample than previous research, including 935,887 flu-vaccinated patients and 935,887 unvaccinated patients.
During four-year follow-up visits, it was found that approximately 5.1% of patients vaccinated against influenza had developed Alzheimer’s disease. Meanwhile, 8.5% of unvaccinated patients had developed Alzheimer’s disease during follow-up.
According to Bukhbinder and Schulz, these results underscore the strong protective effect of the influenza vaccine against Alzheimer’s disease. However, the underlying mechanisms behind this process require further investigation.
“Because there is evidence that multiple vaccines can protect against Alzheimer’s disease, we think it’s not a specific effect of the flu vaccine,” said Schulz, who is also the Umphrey Family Professor of Neurodegenerative Diseases and director of the Neurocognitive group Disorders is center at McGovern Medical School.
“Instead, we think the immune system is complex and some changes, like pneumonia, can activate it in a way that makes Alzheimer’s disease worse. But other things that activate the immune system may do so in a different way — one that protects against Alzheimer’s disease. Of course, we still have to learn more about how the immune system worsens or improves the outcomes of this disease.”
Alzheimer’s disease affects more than 6 million people in the United States, with the number of sufferers increasing due to the country’s aging population. Previous studies have found a reduced risk of dementia associated with prior exposure to various adult vaccinations, including vaccinations for tetanus, polio, and herpes, in addition to flu shots and others.
As more time elapses since the COVID-19 vaccine was launched and longer follow-up data becomes available, Bukhbinder says it will be worth investigating whether there is a similar association between the COVID-19 vaccine and the risk of Alzheimer’s disease.
About these vaccinations and news from Alzheimer’s research
Author: press office
Source: UT Houston
Contact: Press Office – UT Houston
Picture: The image is in the public domain
Original research: Open access.
“Risk of Alzheimer’s disease after influenza vaccination: A claims-based cohort study using propensity score matching” by Avram S. Bukhbinder et al. Journal of Alzheimer’s Disease
See also
abstract
Alzheimer’s Risk After Influenza Vaccination: A Claim-Based Cohort Study Using Propensity Score Matching
Background:
Previous studies have found a reduced risk of dementia of any etiology after influenza vaccination in select populations, including veterans and patients with severe chronic medical conditions. However, the effect of influenza vaccination on the risk of Alzheimer’s disease (AD) in a general cohort of older US adults has not been characterized.
Objective:
Comparison of AD event risk between patients with and without prior influenza vaccination in a large US claims database.
Methods:
Deidentified damage data from September 1, 2009 to August 31, 2019 was used. Eligible patients were dementia-free during the 6-year follow-up period and ≥ 65 years old at the start of follow-up. Propensity score matching (PSM) was used to create influenza vaccinated and influenza unvaccinated cohorts with similar baseline demographics, medication intake, and comorbidities. Relative risk (RR) and absolute risk reduction (ARR) were estimated to assess the effect of influenza vaccination on AD risk during the 4-year follow-up.
Results:
From the unsurpassed sample of eligible patients (n= 2,356,479), PSM produced a sample of 935,887 influenza vaccinated and non-vaccinated couples. The matched sample was 73.7 (SD, 8.7) years old and 56.9% female, with a median follow-up of 46 (IQR, 29-48) months; 5.1% (n= 47,889) of influenza-vaccinated patients and 8.5% (n= 79,630) of non-vaccinated influenza patients 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), resulting in a treatable number of 29.4.
Conclusion:
This study shows that influenza vaccination is associated with a reduced risk of AD in a nationwide sample of US adults age 65 and older.
