People who received at least one influenza vaccine were 40% less likely than non-vaccinated people to develop Alzheimer’s disease over the course of the four years examined, according to a new study from UTHealth Houston.
The peer-reviewed research was 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. The study compared the risk of Alzheimer’s disease development between patients with and without at least one prior flu vaccination with a sample size of almost a million subjects of elderly US adults aged 65 and older.
The study came after a link between the flu vaccine and reduced risk of Alzheimer’s disease was discovered by UTHealth Houston researchers two years prior. This research is a significant step up, having analyzed a much larger sample than the previous research, including 935,887 flu-vaccinated patients and 935,887 non-vaccinated patients.
“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.
“We found that flu vaccination in older adults reduces the risk of developing Alzheimer’s disease for several years."Avram S. Bukhbinder, MD
“Future research should assess whether flu vaccination is also associated with the rate of symptom progression in patients who already have Alzheimer’s dementia,” Bukhbinder said.
During the four year study period, follow-up appointments found about 5.1% of flu-vaccinated patients have developed Alzheimer’s disease. Meanwhile, 8.5% of non-vaccinated patients had developed Alzheimer’s disease during follow ups.
Complex immune system
“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,” Schultz explained.
Today, Alzheimer's is at the forefront of biomedical research. Researchers are working to uncover as many aspects of Alzheimer's disease and other dementias as possible. Some of the most remarkable progress has shed light on how the disease affects the brain. The hope is this better understanding will lead to new treatments. Many potential approaches are currently under investigation worldwide.