Many of you will have seen in the national and international news, dementia research that has found an important link between gum disease and the progression of Alzheimer's disease. BRACE has part-funded a research project for some time looking in to this specific area. We asked one of the project's leading researchers, Dr Shelley Allen-Birt, to explain more about the research and why the findings may be taking us one step closer to a cure for Alzheimer's disease. 

The recent study by Dominy and multinational colleagues*, showing that P. gingivalis bacteria are present in Alzheimer's disease brain, will provide a boost for researchers who have been trying to draw attention to the concept that amyloid is produced excessively in Alzheimer's brains as a response to microbial infections. Since amyloid is now known to be an antimicrobial peptide, this makes sense. The inflammation caused by amyloid would be an attempt by the brain to kill bacteria or other microbes invading the brain.

We know that P. gingivalis is a dental pathogen able to cause disease states in areas of the body - other than the mouth, (for instance cardiovascular disease), and researchers have surmised for some time that it is likely to play a part in Alzheimer's disease. Dominy and colleagues have shown that P. gingivalis infects the brain tissue and produces Alzheimer-like pathology. Notably, the authors also present evidence that blocking the toxic 'gingipain' proteins, produced by the bacteria, prevents the disease process. This is important since we know that broad spectrum antibiotics do not tend to be very successful in stopping  P. gingivalis. However, it should also be noted that other researchers have provided very good evidence for the presence of other microbes in Alzheimer's brain, including spirochetes, Chlamydia pneumonae and viruses, in particular HSV-1. The Dominy study marks a very important step forward and we all hope that the inhibitors will prove successful in the near future in the clinical trial in Alzheimer's patients. It also shows that dentists have an even more important role than we thought they had! 

Our BRACE funded work at the University of Bristol, complements this study. We have previously shown that there is an increase in bacterial markers in the Alzheimer's brain and that this represents a range of different types of bacteria**. 

The presence of these microbes may go alongside the gradual decline in our immune response and vulnerability of our blood-brain barrier which normally protects us. We are conducting further studies on this and at the same time have an ongoing feasibility trial at Bristol Dental Hospital, also funded by BRACE, looking at the effect of providing dental treatment for periodontitis in those individuals with Alzheimer's disease. 

Researchers: At Southmead Hospital: Shelley J Allen-Birt and David C Emery.  At the Medical School: Deborah K Shoemark 

At Bristol Dental Hospital: Professor Nicola X West, Maria Davies, Tanya L Cerajewska, Jelena Taylor, Barbara Warnes, Nikki Hellin, Emma MacDonald

*Stephen S. Dominy et al (2019)  Porphyromonas gingivalis in Alzheimer’s disease brains: Evidence for disease causation and treatment with small-molecule inhibitors. Sci. Adv. 2019; 5 : eaau3333

** David C Emery et al (2017) 16S rRNA Next Generation Sequencing Analysis Shows Bacteria in Alzheimer’s Post-Mortem Brain. Front. Aging Neurosci. 9:195.

This article was submitted by Doctor Shelley Allen-Birt