A bottle of flu vaccine at a CVS and MinuteClinic pharmacy on September 10, 2021 in Miami, Florida.Picture: Joe Raedle (Getty Images)
New research suggests even more benefits for flu vaccination in the elderly. The study found that adults over the age of 65 who received at least one flu vaccine were noticeably less likely to be diagnosed with Alzheimer’s disease until four years later. More research will be needed to confirm a cause-and-effect link and to find out where this protective effect comes from, however.
Alzheimer’s disease is the most common form of dementia and is believed to currently affect more than 5 million Americans. There are lifestyle habits that can reduce a person’s risk of Alzheimer’s, such as regular exercise, and there are medications that can help control their symptoms. But there are no known treatments to prevent or substantially reverse their progression. However, some research has pointed to a relationship between certain infections and Alzheimer’s, which has led to hopes that preventing or treating these infections can reduce their incidence or delay their onset.
In 2020, researchers at the Center for Health Sciences at the University of Texas at Houston analyzed medical records and found a link between flu vaccination and a lower associated risk of diagnosing Alzheimer’s. This time, they turned to an even larger database of medical claims and were able to compare the results of nearly one million adult couples over the age of 65 in the United States who were vaccinated or unvaccinated against the flu. Couples were paired on factors such as age and followed for an average of 46 months.
During the study period, 8.5% of unvaccinated adults were diagnosed with Alzheimer’s or received medications that were often used to control it, compared with 5.1% of vaccinated individuals, a relative risk. approximately 40% lower. There also appeared to be a cumulative effect, so people who were constantly vaccinated annually during the study period were the least likely to develop Alzheimer’s. The findings were published online this month in the Journal of Alzheimer’s Disease.
Studies in recent years have suggested that certain germs may hide in the brain after an infection earlier in life and directly trigger the development of Alzheimer’s, especially herpesviruses. But the authors speculate that the connection observed in this study is not necessarily exclusive to influenza. Rather, it is more about the relationship between our immune system and the aging brain.
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“Because there is evidence that several vaccines can protect against Alzheimer’s disease, we are thinking that it is not a specific effect of the flu vaccine,” said study author Paul Schulz, director of the Center for Alzheimer’s Neurocognitive Disorders at UG McGovern Medical School. a statement. “Instead, we believe that the immune system is complex and some disorders, such as pneumonia, can activate it in a way that worsens Alzheimer’s disease. But other things that activate the immune system can do it in a different way, one that protects you from Alzheimer’s disease. “
Such observational studies can only demonstrate a correlation between two things, not clearly demonstrating a cause-and-effect link between vaccination and Alzheimer’s risk. But other research teams have found a similar connection. And, of course, flu vaccines and other diseases are still effective in preventing serious diseases of the germs they target, benefits that are usually even more pronounced for the elderly.
It will take time to find out exactly why vaccines can help keep our brains in good shape, but they are already doing us great. Researchers, meanwhile, may plan to study whether covid-19 vaccines may offer a similar dampening effect against dementia.