TB vaccine may have protective effect against Alzheimer's: Study

Treatment with the Bacillus Calmette-Guerin (BCG) vaccine—which prevents tuberculosis—is associated with a reduced risk of Alzheimer's disease and related dementias, according to a study.

The BCG vaccine has been found to offer multiple beneficial effects, and is currently a recommended therapy for non–muscle-invasive bladder cancer, the researchers said.

The team at Massachusetts General Hospital (MGH) and Brigham and Women's Hospital (BWH), US followed 6,467 individuals for up to 15 years after they were diagnosed with non–muscle-invasive bladder cancer.

The group included 3,388 patients who underwent BCG vaccine treatment and 3,079 who served as controls, matched by factors such as age, sex, and medical co-morbidities.

During follow-up, the study published in the journal JAMA Network Open found that 202 patients in the BCG vaccine group and 262 in the control group developed Alzheimer's disease and related dementias.

The incidence was 8.8 per 1,000 person-years and 12.1 per 1,000 person-years in the respective groups, the researchers said. Analyses revealed that treatment with the BCG vaccine was associated with a 20 per cent lower risk of Alzheimer's disease and related dementias.

The protective association was greater in patients aged 70 years or older. Additionally, during follow-up, 751 patients in the BCG vaccine group and 973 in the control group died.

Treatment with BCG vaccine was associated with a 25 per cent lower risk of death, according to the researchers.

"A vaccine like BCG, if proven effective, is a perfect example of a cost-effective, population-health–based solution to a devastating illness like Alzheimer's disease," said Weinberg.

"We are shifting our focus towards studying the potential benefits of BCG vaccination of older adults in Alzheimer's disease–related clinical trialsm," he added. Weinberg and his colleagues noted that if a causal link is found, it will be important to understand the mechanisms involved, adding the BCG vaccine's effects on the immune system may play a role.