Is Oral Health Linked to Alzheimer's?

Ageing, genetics, gender, ethnicity – there are a number of uncontrollable risk factors for Alzheimer’s. According to a new privately-sponsored study, poor oral health may be another factor. The study, funded by biotech start-up Cortexyme Inc, has found that the bacteria that causes gum disease is also present in the brains of people with Alzheimer’s.

Recently, there has been an influx of research questioning whether microbial infections contribute to Alzheimer’s disease. This new study, however, has provoked debate into whether the presence of ‘Porphyromonas gingivalis’ (p-gingivalis) is a small contributing factor or an actual cause of the disease.

Study results

Researchers from Cortexyme Inc worked with laboratories across Europe, New Zealand, the United States and Australia to confirm that p-gingivalis can be found in the brains of deceased people with Alzheimer’s and that the microbe is also found in living patients’ spinal fluid.

During their research, the team noticed that toxic enzymes, known as gingipains, were present in over 90% of the brains sampled, caused by the p-gingivalis. Brains with more gingipains typically have higher quantities of tau and ubiquitin, proteins linked to Alzheimer’s.

To discover whether p-gingivalis was causing Alzheimer’s disease, the research team swabbed the gums of healthy mice with the bacteria for 6 weeks to transfer an infection. The bacteria was later detected in the mice brains, as well as higher than average levels of beta-amyloid and dying neurons. The gingipains, whose job is to chop up proteins, damaged the tau and ultimately spurred the formation of tau tangles, commonly found in the brains of those with Alzheimer’s.

Moving forward

Having discovered this link between p-gingivalis and Alzheimer’s, the researchers gave mice a drug to bind gingipains to test their theory further. The binding drug cleared p-gingivalis from the brain better than a common antibiotic and reduced beta-amyloid production significantly, decreasing neurodegeneration.

The drug was tested on human volunteers, showing signs of improved cognition of nine Alzheimer’s patients. Researchers plan on conducting a larger study this year to further clarify the validity of this drug.

While this study does not provide concrete evidence that those with gum disease will develop Alzheimer’s, it places more importance on taking care of your oral health. As James Nobel from Columbia University points out, “the main conclusion we still have is: brush and floss”.

When it comes to drug delivery for Alzheimer’s and a range of other diseases, one of the most promising fields of research is into nanoparticles as potential vehicles. The article ‘Accurate Measurements of Biological Nanoparticles’ discusses how nanoparticles can be accurately measured for both size and concentration.