Make sure you don't skip your vaccines. A new study says several routine vaccines given to adults, including those for tetanus, diphtheria and shingles, can help lower the risk of Alzheimer's disease.

Alzheimer's is a brain disorder associated with diminishing memory and thinking capacity. There is no cure for the debilitating condition that affects at least 55 million people in the world.

In the latest study, published in the Journal of Alzheimer's, researchers say the immune system is responsible for brain cell dysfunction associated with Alzheimer's.

A team from UTHealth Houston evaluated the medical records of 1.6 million patients who were dementia-free for two years before the study. All participants were at least 65 years old at the commencement of an 8-year follow-up period.

The study suggests people vaccinated against shingles, pneumococcus, tetanus and diphtheria, with or without an added pertussis vaccine, are at a 25% to 30% reduced risk of developing Alzheimer's disease.

Participants who received the Tdap/Td vaccine to protect against tetanus and diphtheria had a 30% less chance of developing Alzheimer's disease compared to those who did not receive the shots. With shingles and pneumococcal vaccinations, the risk was reduced to 25% and 27% respectively.

The study concludes that with routine vaccinations, the risk of Alzheimer's disease is reduced in older adults.

"This study goes hand in hand with our previous research, which found that people who received at least one flu vaccine were 40% less likely to develop Alzheimer's disease when compared with those who were not vaccinated," said Kristofer Harris, co-first author of the study.

"The findings suggest to us that vaccination is having a more general effect on the immune system that is reducing the risk for developing Alzheimer's," noted Dr. Paul Schulz, a senior author of the study. "Vaccines may change how the immune system responds to the build-up of toxic proteins that contribute to Alzheimer's disease, such as by enhancing the efficiency of the immune cells at clearing the toxic proteins or by 'honing' the immune response to these proteins so that 'collateral damage' to nearby healthy brain cells is decreased. Of course, these vaccines protect against infections like shingles, which can contribute to neuroinflammation."