Bacillus Calmette‐Guérin (BCG) treatment of bladder cancer protects against Alzheimer’s Disease in older adults: The Massachusetts General Brigham cohort

Retraining the immune system offers a potential means of preventing or treating Alzheimer’s disease (AD). Vaccines can confer non‐specific beneficial effects (NSBEs), impacting diseases far afield from the original target. The Bacillus Calmette‐Guérin (BCG) vaccine, used worldwide in the prevention of tuberculosis, causes NSBE on non‐TB respiratory infections, type 1 diabetes, and multiple sclerosis. BCG is the gold‐standard therapy for non–muscle‐invasive bladder cancer. Recently, several retrospective studies have associated intravesicular BCG treatment of bladder cancer with lowered risk of AD (Gofrit et al., 2019, Klinger et al., 2021, Kim et al., 2021). We sought to replicate the retrospective study in a large cohort of patients in the Massachusetts General Brigham (MGB) System.