Periodontal Bacteria Found in Some Alzheimer's Brain Tissue
By Nancy Volkers
InteliHealth News Service
INTELIHEALTH - A small study suggests that the brains of people with Alzheimer's disease may be vulnerable to infection with some of the bacteria that cause periodontal disease. This could lead to further declines in thinking and memory.
The study involved 20 people. All had donated brain tissue after death. Ten of the people had Alzheimer's disease. They ranged in age from 77 to 85. The other 10 people died at similar ages, but did not have Alzheimer's disease.
Brain tissue was examined for three types of bacteria: Treponema denticola, Tannerella forsythia and Porphyromonas gingivalis. These are the three main types of periodontal disease bacteria.
Researchers found the bacteria in 4 of the 10 samples of brain tissue from people with Alzheimer's disease. They were not found in the brain tissue of anyone who did not have the disease.
Another, similar study found Treponema bacteria in 14 of 16 samples of brain tissue from Alzheimer's patients.
The blood-brain barrier normally protects the brain from infection with bacteria. However, the authors suggest Alzheimer's patients may have weakened immune systems that allow some bacteria to get into the brain. Once this happens, the brain can react by releasing potentially toxic molecules. These molecules are meant to fight the infection. However, they can affect brain tissue as well. This could lead to further problems with thinking and memory.
The study was published in the May issue of the Journal of Alzheimer's Disease.