Dear Dr. Roach: Ive read mixed reviews as to whether the flu shot can contribute to Alzheimers disease. Im anxious to see your input. J.W.
Answer: There is no reliable evidence, nor any good biological plausibility, that influenza vaccination increases the risk of either Alzheimers disease or other types of dementia. In fact, there are several studies showing a reduced risk of dementia in people who get regular influenza vaccines. I have read well-done studies looking at people with heart failure, people with kidney disease and overall people over age 65 - all show a decreased risk of dementia among those who regularly get the vaccine.
There is a risk in these kinds of studies, because people who get regular vaccines are more likely to see their doctors, have blood pressure and blood sugar well-controlled, eat better and exercise more, all of which help protect against dementia. However, the authors did their best to statistically control for these factors and still found a benefit from regular vaccination.