Alzheimer’s disease – the most common type of dementia – affects an estimated 24 million people around the world (and more than five million in the US alone) and is predicted to triple by 2030 as the global population continues to age.
The global total includes an estimated 5.6 million people age 65 and older and approximately 200,000 individuals under age 65 who have younger-onset Alzheimer’s. One in 10 people over 65 has Alzheimer’s disease, while the rate increases to one third at age 85 and older.
There is no cure, but now there may be a glimmer of hope. There are data reaching back to the 1960s showing that countries that treated bladder-cancer patients with the bacillus Calmette-Guérin (BCG) vaccine – originally developed for tuberculosis –had a lower prevalence of Alzheimer’s disease, but it hadn’t been properly analyzed.
A research team headed by Hebrew University of Jerusalem microbiology and molecular genetics Prof. Hervé Bercovier has discovered that this TB vaccine also be an effective treatment to prevent Alzheimer’s. Bercovier published the findings along with Profs. Charles Greenblatt, Benjamin Klein, Tamir Ben-Hur, Ofer Gofrit and Irun Cohen, who are colleagues in his department, in the journal PLOS ONE. It was titled: “Bacillus Calmette-Guerin (BCG) Therapy Lowers the Incidence of Alzheimer’s Disease in Bladder-Cancer Patients.”
Thus far, there is no cure or even disease-modifying treatment for this disease, they wrote. “While cardiovascular mortality was cut by more than a half in the past 30 years and cures were found for many types of cancer, no cure or even disease-modifying treatment has been found for AD. Any treatment that decreases the incidence of AD or delays its onset will have a substantial impact on the individual and on society,” they continued.
“The immune system is a major player in the pathogenesis of Alzheimer’s disease. BCG modulates the immune system and reduces recurrence of non-muscle invasive bladder cancer. Theoretical considerations suggested that treatment with BCG may decrease the risk of AD. We tested this hypothesis on a natural population of bladder-cancer patients.”
The team followed 1,371 bladder cancer patients receiving treatment at the two Hadassah University Medical Centers (two campuses located at the opposing edges of Jerusalem and serving about 1.5 million people, from both the Jewish and the Arab populations), with data retrieved from their computerized archives. The archives of the Hadassah-University medical hospitals provide a unique source of long-term follow-up on many types of pathologies.
The average patient age was 68. During follow-up visits, 65 cancer patients had developed Alzheimer’s. Those who had not received BCG as part of their treatment (8.9% or 44 patients) had a significantly higher risk of developing Alzheimer’s than did those who received the BCG vaccine (2.4% or 21 patients).
In addition, when compared with the healthy population, people who had never been treated with BCG had a four-fold-higher risk for developing Alzheimer’s than did those who were treated with BCG.
The team stress that they have not developed a vaccine that prevents Alzheimer’s. But, said Bercovier, “our study is an important step towards understanding the ways in which our immune system is a major player in the pathogenesis of Alzheimer’s and how the BCG vaccine, which modulates the immune system, may serve as an effective preventative treatment to this crippling condition.”