A team of researchers recently discovered a link between a bacterium that causes periodontitis and Alzheimer’s disease or various forms of it cancer.
The study gives hope to scientists about a possibility to reduce the number of patients with periodontal disease.
The bacterium Fusobacterium nucleatum can cause Alzheimer’s and cancer
Gum disease – also known as periodontitis and periodontal disease – occurs through a bacterial infection in the soft tissues of the mouth. Previous research links periodontitis to diabetes, they were of kidneys and cardiovascular problems, according to medicalnewstoday.com.
Now, a team of researchers from Tufts University has found a correlation between gum disease caused by the bacterium Fusobacterium nucleatum (F. nucleatum ) and Alzheimer’s disease through a study done on mice. The scientists believe their findings may help reduce the progression of periodontal disease and this form of dementia.
The study was recently published in the journal Frontiers in Aging Neuroscience.
What is periodontal disease?
Food particles and bacteria are constantly in the mouth. When people don’t brush and floss regularly, the particles and bacteria form a sticky substance called plaque that sticks to the teeth. Plaque can irritate the gums if left untreated, causing an early form of gum disease called gingivitis.
If plaque sits too long on the teeth and gums, it hardens into a substance known as tartar. Because tartar is very hard, normally only a dentist can remove it with dental instruments during a professional teeth cleaning.
When tartar remains on the teeth for too long, the next level of gum disease known as periodontitis can set in. Periodontal disease leads to more infection of the gums and teeth. If left untreated, periodontitis can lead to tooth loss.
The link between periodontal disease and Alzheimer’s disease and cancer
According to Dr. Jake Jinkun Chen, professor of periodontology and director of the Division of Oral Biology at Tufts University School of Dental Medicine and lead author of this study, the goal of this new study is to identify and characterize the association between F. nucleatum-induced periodontal disease with Alzheimer’s disease.
F. nucleatum is a bacterium frequently implicated in periodontal disease. Previous research also links the bacteria to colon and mouth cancer.
How could mouth bacteria exacerbate Alzheimer’s symptoms? It can do two things, Dr. Chen told MNT.
“First, it generates inflammation both locally and systemically, which will affect the phenotype of Alzheimer’s disease, because Alzheimer’s itself is an inflammatory disease,” the doctor explained. “Secondly, it migrates and penetrates into brain to colonize there and secrete pathological molecules to exacerbate the symptoms and signs of Alzheimer’s disease.”
For this study, Dr. Chen and his team used cells grown in a laboratory to show that the presence of F. nucleatum caused the abnormal growth of microglial cells. These immune cells in the brain and spinal cord help clear any infection from the brain, keeping the central nervous system healthy.
In addition to impacting their growth, the presence of F. nucelatum also caused these cells to mount an inflammatory response. Previous research shows that inflammation plays a role in the development of Alzheimer’s disease.
Next, the team looked at F. nucleatum-induced periodontitis in a mouse model of Alzheimer’s disease. They found that compared to control animals, mice with such periodontitis showed increased cognitive impairment and higher levels of amyloid plaques and Tau protein. Moreover, as in cultured cells, increases in microglial cell growth and inflammation were observed in these animals.
How can these findings help?
Dr. Chen said the significance of their research results lies in four main areas. First, they are targeting a “huge health problem” because a significant percentage of the adult population has periodontal disease and more than 55 million people globally are living with dementia. Alzheimer’s is the most common type of dementia.
On the other hand, “the mechanistic understanding of an unstudied anaerobic bacterium (F. nucleatum) in the pathogenesis of periodontal disease and Alzheimer’s disease fills a gap in scientific knowledge and sends a warning signal to dentists and neurologists,” continued Dr. Chen.
“Then establishing an animal model provides the technical ability to delineate the possible [cauzativ] between a local dental disease (periodontal disease) and a neural disorder (Alzheimer’s disease) in an anatomically distant site,” he added.
“And finally, the study may provide proof of principle for further preclinical and clinical applications of the established system to study whether treatment of periodontal disease can decrease or delay the onset of Alzheimer’s disease in humans,” concluded Dr. Chen.
Also, Dr. Percy Griffin, Alzheimer’s Association director of science engagement, believes this study adds to the growing evidence that microbes and viruses can play a role in brain diseases.
“In this study, they found evidence for increased activation of the brain’s immune system, Alzheimer’s-related brain changes, and cognitive changes in mice infected with an oral microbe,” said Dr. Griffin.
“While these findings are interesting, this research was done in mice, and previous studies examining the relationship between periodontal disease and Alzheimer’s disease in humans have not demonstrated causality. More research is needed.”
“We don’t know at this point whether things like brushing your teeth will ultimately reduce the risk of Alzheimer’s,” he added.
“What we can say is that good oral hygiene is important for overall health and healthy aging. There are a number of other modifiable lifestyle risk factors – such as exercise and diet – which have considerable scientific evidence to show that they can reduce the risk of cognitive decline.”
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