Vaccines and dementia
What is it about?
There is growing awareness that infections may contribute to the development of senile dementia including Alzheimer's disease (AD), and that immunopotentiation is therefore a legitimate strategy for the management of diseases of the elderly including AD. Vaccines, adjuvants, and their component molecules can elicit broad-spectrum protective effects against diverse agents, with the example of the bovine TB vaccine strain Bacille Calmette–Guérin (BCG) as a treatment for some types of cancer as well preventing infections of the elderly such as pneumonia. BCG and other vaccines may offer a measure of protection against dementia development. Five studies to date have determined that BCG administration in the urinary bladder, which is the standard of care for bladder cancer, is followed by a mean ~45% reduction in subsequent AD development in these patients. Although this could potentially be ascribed to confounding factors, the finding that other routine vaccines such as against shingles (herpes zoster virus) and influenza (influenza A virus), among others, also offer a degree of protection against AD (mean 29% over multiple studies) underlines the plausibility that the protective effects are real. Planned clinical trials may shed further light on these possibilities. We also discuss whether BCG could be replaced by key components of the mycobacterial cell wall. BCG and similar agents merit wider consideration as potential prophylactic agents against dementia.
Why is it important?
Dementia including Alzheimer's disease is an enormous burden to society and its health system. In suffering and cost it outweighs both heart disease and cancer.