“We found that flu vaccination in older adults reduces the risk of developing Alzheimer’s disease for several years. The strength of this protective effect increased with the number of years that a person received an annual flu vaccine – in other words, the rate of developing Alzheimer’s was lowest among those who consistently received the flu vaccine every year,” said Dr. Bukhbinder, who is still part of Dr. Schulz’s research team while in his first year of residency with the Division of Child Neurology at Massachusetts General Hospital. “Future research should assess whether flu vaccination is also associated with the rate of symptom progression in patients who already have Alzheimer’s dementia.”
The study – which comes two years after UTHealth Houston researchers found a possible link between the flu vaccine and reduced risk of Alzheimer’s disease – analyzed a much larger sample than previous research, including 935,887 flu-vaccinated patients and 935,887 non-vaccinated patients.
During four-year follow-up appointments, about 5.1% of flu-vaccinated patients were found to have developed Alzheimer’s disease. Meanwhile, 8.5% of non-vaccinated patients had developed Alzheimer’s disease during follow-up.
These results underscore the strong protective effect of the flu vaccine against Alzheimer’s disease, according to Dr. Bukhbinder and Dr. Schulz. However, the underlying mechanisms behind this process require further study.
“Since there is evidence that several vaccines may protect from Alzheimer's disease, we are thinking that it isn't a specific effect of the flu vaccine,” said Dr. Schulz, who is also the Umphrey Family Professor in Neurodegenerative Diseases and director of the Neurocognitive Disorders Center at McGovern Medical School. “Instead, we believe that the immune system is complex, and some alterations, such as pneumonia, may 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 from Alzheimer's disease. Clearly, we have more to learn about how the immune system worsens or improves outcomes in this disease.”
Alzheimer’s disease affects more than 6 million people living in the US, with the number of affected individuals growing due to the nation’s aging population. Past studies have found a decreased risk of dementia associated with prior exposure to various adulthood vaccinations, including those for tetanus, polio, and herpes, in addition to the flu vaccine and others.
Additionally, as more time passes since the introduction of the COVID-19 vaccine and longer follow-up data becomes available, Dr. Bukhbinder said it will be worth investigating whether a similar association exists between COVID-19 vaccination and the risk of Alzheimer’s disease.
Co-authors from McGovern Medical School included Omar Hasan, research coordinator in the Department of Neurology and student at The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences; Kamal N. Phelps, fourth-year medical student; Srivathsan Ramesh, PhD, first-year resident in the Department of Orthopedic Surgery; and alumni Albert Amran, MD, and Ryan Coburn, MD. Co-authors from UTHealth Houston School of Biomedical Informatics included Yaobin Ling, graduate research assistant; Xiaoqian Jiang, PhD, the Christopher Sarofim Family Professor in Biomedical Informatics and Engineering; and Yejin Kim, PhD, assistant professor. Qian Xiao, PhD, MPH, assistant professor in the Department of Epidemiology and Disease Control with UTHealth School of Public Health, also co-authored the study.
Photo cption: A team of researchers including Paul E. Schulz, MD, found that flu vaccination was associated with a reduced risk for Alzheimer's disease over a four-year period (photo credit: UTHealth Houston)
Written by: Caitie Barkley
NOTES FOR EDITORS
Full open access study: "Risk of Alzheimer’s Disease Following Influenza Vaccination: A Claims-Based Cohort Study Using Propensity Score Matching" by Avram S. Bukhbinder, Yaobin Ling, Omar Hasan, Xiaoqian Jiang, Yejin Kim, Kamal N. Phelps, Rosemarie E. Schmandt, Albert Amran, Ryan Coburn, Srivathsan Ramesh, Qian Xiao, and Paul E. Schulz (DOI: 10.3233/JAD-220361), published online in the Journal of Alzheimer’s Disease in advance of the publication of Volume 88, Issue 3. The open access article is available at: content.iospress.com/articles/journal-of-alzheimers-disease/jad220361.
Further information can be obtained from the media office at UTHealth Houston (+1 713 500 3030).
About the Journal of Alzheimer's Disease
Now in its 24th year of publication, the Journal of Alzheimer’s Disease (JAD) is an international multidisciplinary journal to facilitate progress in understanding the etiology, pathogenesis, epidemiology, genetics, behavior, treatment, and psychology of Alzheimer’s disease. The journal publishes research reports, reviews, short communications, book reviews, and letters-to-the-editor. Groundbreaking research that has appeared in the journal includes novel therapeutic targets, mechanisms of disease, and clinical trial outcomes. JAD has a Journal Impact Factor of 4.160 according to Journal Citation Reports (Clarivate, 2022). j-alz.com