The Bacillus Calmette-Guérin (BCG) vaccine—which prevents tuberculosis—offers multiple beneficial effects, and it’s currently a recommended therapy for non–muscle-invasive bladder cancer. In a new study led by investigators at Massachusetts General Hospital (MGH) and Brigham and Women’s Hospital (BWH), treatment with the BCG vaccine was associated with a reduced risk of Alzheimer’s disease and related dementias. The findings are published in JAMA Network Open.