Flu vaccine protective against Alzheimer’s disease

Researchers from the University of Texas Health Science Center at Houston (UT Health Houston) have found that older adults vaccinated at least once against influenza (flu) were 40% less likely to develop Alzheimer’s disease than their non-vaccinated peers. This protective effect was strengthened following an annual flu vaccine shot, said Dr. Avram Bukhbinder, a neurology major and alumnus of McGovern Medical School at UTHealth Houston.

UTHealth Houston researchers had earlier found a possible link between the flu vaccine and reduced risk of Alzheimer’s disease, and this time analysed the same in a larger sample of US adults aged 65 and older. The latest study included 935,887 flu-vaccinated patients and 935,887 non-vaccinated patients.

Only about 5.1% of flu-vaccinated patients were found to have developed Alzheimer’s disease during the study period, while 8.5% of non-vaccinated patients had developed Alzheimer’s disease during follow-up.

“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,” explained Dr. Bukhbinder.

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.

“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. Paul Schulz, Professor in Neurology at McGovern Medical School.

“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 [to protect] from Alzheimer’s disease. Clearly, we have more to learn about how the immune system worsens or improves outcomes in this disease.”

The researchers will now investigate whether a similar association exists between COVID-19 vaccination and the risk of Alzheimer’s disease.

Category: Features, Pharmaceuticals