Bacillus Calmette-Guérin (BCG), the tuberculosis vaccine used worldwide to prevent the disease, may also slow dementia progression, according to a Johns Hopkins University study published in Science Advances.
The study examined responses in mice and found that the vaccine can «train» immune cells to eliminate harmful tau protein deposits. As a result, scientists reported a fourfold reduction in brain inflammation, prevention of the activation of over 700 genes related to Alzheimer’s disease and preservation of cognitive function.
BCG vaccination and mice
For the study, biologists used genetically modified mice that exhibit symptoms of late-stage Alzheimer’s disease. The subjects were divided into groups: one group received the BCG vaccine at three months of age, while control groups — consisting of both mice with dementia and healthy mice — received normal saline.
Nine months after vaccination, the researchers conducted a comprehensive assessment. They evaluated brain structure and volume using neuroimaging, measured neuroinflammation markers and analyzed gene activity at the molecular level. They also tested the mice’s cognitive function and memory using standard tasks involving object recognition and recall.
Research findings
Group comparisons revealed significant differences. Mice that received the BCG vaccine showed a fivefold greater reduction in tau protein deposits and a fourfold decrease in markers of neuroinflammation. In untreated animals, the disease affected 716 genes associated with cell death and inflammatory processes; by contrast, the BCG vaccine normalized the expression of 707 of these genes. Consequently, the vaccinated animals experienced less brain atrophy, better memory retention, and longer lifespans.
Why is this study significant?
Previously, similar positive effects had been observed only at early stages — specifically, in cases of amyloidosis. This new experiment shows that innate immunity, when «trained» by a vaccine, can compel brain cells to clear protein deposits, even after the disease has progressed.