Vaccines protect us from infectious diseases, but perhaps also from dementia. The hypothesis that training the immune system against viruses and bacteria helps ward off Alzheimer’s has been around for some time, and is gradually finding new supporting evidence. Among the last to arrive those published on pages of the Journal of Alzheimer’s Disease, which states that vaccines against tetanus, diphtheria, whooping cough, herpes zoster and pneumococcus reduce the risk of Alzheimer’s. By how much? On average a quarter or a third compared to those who do not get vaccinated.
Risk factors for Alzheimer’s
The hunt for the possible causes of Alzheimer’s is as lively as ever, even if it has not yet led to concrete results. Among the possible causes and risk factors, we think of genetics, age and lifestyle. In fact, it seems that not smoking, following a healthy diet and carrying out physical activity can help avoid developing dementia. But the picture is more complicated and there are more and more clues that invite us to look elsewhere, for example at education, loneliness or hearing loss. The effects – whatever the causes – are memory problems, mood changes, confusion, difficulty moving and speaking. Perhaps, however, another role also plays a role: whether or not one has been vaccinated or, similarly, has contracted some infections.
by Simone Valesini
Vaccines reduce the risk of dementia
Paul Schulz of the University of Texas Health Science Center in Houston and colleagues have in fact put together some data that invite us to look at vaccines as protectors against dementia. The data concern various vaccines administered to the elderly (but not only), such as those against diphtheria-tetanus and whooping cough, against pneumococcus, against zoster, or influenza. They come from complex analyses, which have collected information present in the health and administrative registers of a large number of people (from around one hundred thousand to almost one million, depending on the case), analyzed with Education retrospectives. In this case, scientists used a method that, retrospectively, allows vaccinated people to be compared with non-vaccinated people by limiting confounding factors. In this way they were able to estimate the risk of developing Alzheimer’s in people over sixty-five followed for several years.
In this way they calculated that the risk of Alzheimer’s after diphtheria/tetanus and pertussis vaccine (even in the formulation without pertussis) was reduced by 30% and similar percentages were also observed for the pneumococcal vaccine. The risk, however, was reduced by 25% with the zoster vaccine and up to 40% in the case of influenza vaccines (as estimated in a previous study). In the general population the risk today of developing dementia over the course of life according to the latest data spread by Alzheimer’s & Dementia is approximately 21% for a 65-year-old woman compared to 11% in men.
by Celeste Ottaviani
How do vaccines protect the brain in older adults?
But how could vaccines protect against the risk of Alzheimer’s? In addition to the possibility that vaccines, by protecting against individual diseases, also protect against their complications, such as inflammation of the nervous system, there is more. As scientists tell it, vaccines can somehow prepare the immune system to fight the signs of Alzheimer’s. Directly or indirectly, as clarified by Avram Bukhbinder, who took part in the research. “Vaccines can change the way the immune system responds to the buildup of toxic proteins that contribute to Alzheimer’s disease, for example by improving the efficiency with which immune cells eliminate toxic proteins or by ‘fine-tuning’ the immune response to them. proteins so that ‘collateral damage’ to nearby healthy brain cells is reduced.”
The hypothesis of a generic mechanism, which applies to different vaccines as actually observed, is particularly strong according to the authors, and to understand whether there is a link between vaccines and the risk of Alzheimer’s, perhaps the most appropriate and ethically acceptable path could be that to conduct studies on animal models, the authors conclude.