TB Vaccine May Cut Alzheimer's Risk

A study published in Communications Medicine suggests that the Bacillus Calmette-Guérin (BCG) vaccine, commonly used for tuberculosis, may influence biological pathways related to Alzheimer's disease. The vaccine has been observed to remodel the brain's immune environment, potentially explaining links between BCG and a reduced risk of Alzheimer's.

Findings from the study indicate that BCG promotes increased responsiveness in immune cells surrounding the brain and modifies Alzheimer's-related biomarkers in healthy older adults. This phenomenon is attributed to 'trained immunity,' where innate immune cells undergo long-lasting functional reprogramming after exposure to microbial stimuli, persisting for months or even years.

The research involved 23 adults aged 55 and older. Results showed BCG shifted levels of amyloid-beta in cerebrospinal fluid and blood. In participants without Alzheimer's pathology, amyloid levels declined in brain fluid while increasing in blood samples over 12 months. This shift was not observed in those with existing Alzheimer's pathology, suggesting that the timing of BCG administration could impact early disease dynamics and protein clearance from the central nervous system.

While these findings are promising, indicating that controlled immune stimulation can influence Alzheimer's-related pathways, larger randomized clinical trials are necessary. Such studies will help determine if BCG could prevent or treat Alzheimer's disease and distinguish its effects from prior vaccination or existing infections.