People who received at least one influenza vaccine were 40% less likely than their non-vaccinated peers to develop Alzheimer's disease over the course of four years, according to a new study.
From: University of Texas Health Science Center at
Houston
June 24, 2022 -- Research
led by first author Avram S. Bukhbinder, MD, a recent alumnus of McGovern
Medical School at UTHealth Houston, and senior author Paul. E. Schulz, MD, the
Rick McCord Professor in Neurology at McGovern Medical School, compared the
risk of Alzheimer's disease incidence between patients with and without prior
flu vaccination in a large nationwide sample of U.S. adults aged 65 and older.
An early online version
of the paper detailing the findings is available in advance of its publication
in the Aug. 2 issue of the Journal of Alzheimer's Disease.
"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 Bukhbinder, who is still part
of 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 Bukhbinder and 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 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 U.S., 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, 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.
https://www.sciencedaily.com/releases/2022/06/220624123814.htm
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