Evidence suggests that common vaccines may protect against Alzheimer’s

Usually when we think of a vaccine, we imagine a substance that is administered to stimulate an individual’s immune response to a particular infectious microorganism with the aim of protecting him/her against the disease caused by that agent. Recent new evidence suggests that vaccinations against some of the most common infectious diseases would also protect against Alzheimer’s disease.

For some years there have been empirical observations in support of the idea that the activation of the immune system could prevent or slow down the onset of Alzheimer’s disease. In fact, previously some studies conducted on a limited number of patients had presented encouraging data on a possible relationship between vaccinations and the risk of dementia.

In the new study more than 200,000 adults who had received common vaccinations routinely recommended by the Centers for Disease Control and Prevention, such as diphtheria, tetanus, and pneumococcal vaccines, were compared with a group that had not received any vaccine. At the time of study enrollment, no individual had clinical signs of dementia for at least two years prior to vaccination. All individuals were at least 65 years old at the start of the study and were then followed for eight years. At the end of this period, the number of cases of Alzheimer’s disease developed in each of the two groups was evaluated. The results showed that compared with those who were not vaccinated, individuals who had received one or more of the vaccines indicated above had a 25 percent to 35 percent reduction in the risk of developing Alzheimer’s.

This study is important not only because it confirms preliminary observations on vaccines and the risk of dementia, but also because it is in line with some very recent observations which indicated how exposure to infectious agents (such as the herpes virus) could be considered a new risk factor for Alzheimer’s.

However, the question to which there is still no answer is the following: what is the mechanism through which vaccines would protect against Alzheimer’s disease? One possible answer is that vaccines by providing instructions to the immune system to respond to a particular infectious agent would indirectly prepare immunological cells to respond more effectively to an insult or damage to the brain. Another hypothesis is that vaccines would prepare the immune cells of the brain to produce a protective inflammatory response only, without the negative aspects, and therefore capable of removing any harmful agents without causing damage to the brain.