An older tuberculosis vaccine also used as a cancer therapy has now been linked to a 20% lower risk of Alzheimer’s disease and related dementias. The oldest recipients appear to derive the most benefit, researchers say.
Based on the findings, investigators on Friday reported that they will conduct further study of the Bacillus Calmette-Guérin (BCG) vaccine in Alzheimer’s disease-related clinical trials.
BCG, in use since the 1920s, still is commonly used outside of the United States to prevent TB. It also is commonly recommended as a therapy for non–muscle-invasive bladder cancer, and has been shown to reduce the risk of comorbidities in patients with diabetes who have COVID-19. Small studies have previously linked the vaccine with a reduced risk of dementia as well.
In the new research, investigators followed 6,467 patients for up to 15 years after they were diagnosed with non–muscle-invasive bladder cancer. About half of the patients received BCG vaccine treatment, with the other patients serving as a control group.
During follow-up, 202 patients in the BCG vaccine group and 262 in the control group developed Alzheimer’s disease and related dementias, with the protective association greater in patients aged 70 years or older. Results were not statistically significant after five years. The vaccine was also associated with a 25% lower risk of death.
The researchers theorize that if the BCG vaccine does turn out to be the cause of these relatively better outcomes, its effects on the immune system may play a role.
“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,” study lead Marc S. Weinberg, MD, PhD, of the Massachusetts General Hospital in Boston said in a statement.
Full findings were published in JAMA Network Open.
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