Pre-vaccination against tetanus and diphtheria, shingles and pneumococcus are associated with a reduced risk of developing Alzheimer’s disease. This conclusion was reached by scientists at the University of Texas Health Sciences Center in Houston, who published an article in the Journal of Alzheimer’s Disease.

The researchers conducted a retrospective cohort study that included patients who had not had dementia for a two-year period and who were at least 65 years old at the beginning of the eight-year follow-up period. Two similar groups of patients with and without vaccination were compared, after which the relative risk and reduction in the risk of developing Alzheimer’s disease were calculated.

Patients who received the Tdap/Td vaccine (tetanus and diphtheria vaccine with and without whooping cough) were 30 percent less likely to develop Alzheimer’s disease than their unvaccinated peers (7.2 percent of vaccinated patients versus 10.2 percent of unvaccinated patients). Vaccination against shingles was associated with a 25 percent reduction in the risk of developing Alzheimer’s disease (8.1 percent versus 10.7 percent of unvaccinated). For the pneumococcal vaccine, the risk of developing the disease decreased by 27 percent (7.92 percent versus 10.9 percent of unvaccinated).

For comparison, three new anti-amyloid antibodies used to treat Alzheimer’s disease slow down the progression of the disease by 25, 27 and 35 percent.

According to the authors, vaccines can change how the immune system reacts to the accumulation of toxic proteins that contribute to the development of Alzheimer’s disease. This happens, for example, by increasing the efficiency of immune cells when clearing toxic proteins or by improving the immune response to these proteins. In addition, vaccines protect against infections such as shingles, which can contribute to neuroinflammation.