A study by the University of Texas Health Science Center at Houston has discovered that people aged 65 and over who have received vaccinations are significantly less likely to develop Alzheimer's disease. The study highlighted the importance of vaccinations for protecting against infectious diseases and dementia.
The study was published in the Journal of Alzheimer's Disease.
Alzheimer's affects more than 6 million people in the US, with the number of affected individuals growing due to the nation's aging population.
Most people receive routine vaccinations in childhood, as many vaccines are designed to protect children and their communities from infectious diseases. Vaccines for other serious diseases are just as crucial for older individuals for similar reasons.
Children often receive vaccines to immunize against tetanus, diphtheria, whooping cough, and pneumococcal infection. Tetanus and diphtheria vaccines are bundled up in one vaccine, sometimes including the whooping cough vaccine.
The vaccine to protect against pneumococcal infection is recommended for children under five and adults 65 years and over. People in the US over 50 and people in Australia and the UK over 70 are advised to get vaccines that protect against shingles.
The influenza vaccine
Findings from an earlier study in the same journal showed that people who had received at least one influenza vaccine were 40% less likely to develop Alzheimer's disease compared to unvaccinated people in the same age range.
"We were wondering whether the influenza finding was specific to the flu vaccine. This data revealed that several additional adult vaccines were also associated with a reduction in the risk of Alzheimer's," said Paul Schulz, corresponding author of the study.
"We and others hypothesize that the immune system is responsible for causing brain cell dysfunction in Alzheimer's. 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."
"We hypothesize that the reduced risk of Alzheimer's disease associated with vaccines is likely due to a combination of mechanisms," said Avram Bukhbinder, one of the study's co-authors.
"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."
The researchers stated that while the evidence is compelling, further studies are needed to measure precisely how effective vaccines are in protecting against Alzheimer's.