Alzheimer's disease: when the saliva speaks

It is estimated that every 17 minutes in Switzerland someone receives a diagnosis of some form of dementia. A team of researchers at the University of Fribourg has shown that an analysis of the microbial flora present in saliva enables the early identification of patients at risk. A vital discovery for the implementation of preventative treatments.

In 2019, there were in Switzerland more than 128,209 patients suffering from dementia. Alzheimer’s disease is the most common form of dementia, particularly amongst the elderly, and is characterised by a progressive atrophy of the brain, accompanied by loss of memory. The disease develops progressively with a long asymptomatic phase lasting more than 10 years. Once symptoms of memory loss appear, irreversible processes have long set in, making medical treatments particularly challenging.

Importance of early detection
For the last 20 years– researchers have struggled to develop any disease modifying drug halting the progression of the disease. The failure rate of clinical trials even exceeds 99%! So it is not surprising that there is general agreement that detecting Alzheimer’s disease early on is crucial if one wishes to adopt preventative therapeutic measures for patients at risk.

Signs of the disease in the saliva
In 2019, an American-Polish team was able to demonstrate a link between P.gingivalis, a key periodontal pathogen, and Alzheimer’s disease. It is the same type of indication, hidden in the saliva, which Dr Alberi Auber’s team has succeeded in identifying.
The researchers at SICHH and the University of Fribourg, in collaboration with Professor Jean-Marie Annoni and his neurology team at the Fribourg Cantonal Hospital (HFR), have, as a first step, used olfactory and cognitive tests to identify patients presenting with a loss of sense of smell, a potential indicator of Alzheimer’s disease. They then proceeded to analyse the microbial flora in the saliva of these subjects. This screening procedure has enabled them to show that the flora composition changes  in line with the severity of the disease. These results, published in the prestigious Alzheimer’s & Dementia Journal, show that the saliva, provides an excellent and non-invasive biofluid for diagnosing early stage Alzheimer’s disease.

Prevention is better…since there is yet no cure
This early screening procedure, is essential: in the current absence of effective therapies, as it allows the employment of preventive treatments aimed at limiting oral inflammation, improving personal hygiene and increasing the plasticity of the brain. As the WHO and the Alzheimer’s associations advocates, in the current state of things, preventive strategies remain the most pragmatic solution against dementia’s the progression.

Bathini P, Foucras S, Dupanloup I, Imeri H, Perna A, Berruex J-L, et al. Classifying dementia progression using microbial profiling of saliva. Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring 2020;12:73–7.