The oral microbiome refers to the community of bacteria, viruses and fungi in our mouth. What we eat and drink, along with our overall oral hygiene, impacts the microbiome. New research suggests that certain types of bacteria are linked to the onset of Dementia. These findings underline the importance of oral health.
Recent research suggests that the make-up of the oral microbiome impacts our overall cognitive function as we age [1].
Impaired cognitive function can result in conditions like Dementia developing. Therefore, trying to avoid this is advisable for everyone.
This research reaffirms the importance of oral health, and acts as a reminder of how crucial it is to always look after our teeth and gums.
Cognitive function
This research looked into the impact that oral health has on our cognitive function. Cognitive function refers to the mental processes that we do in terms of thinking and understanding.
Therefore, it results in our actions in day-to-day life. Cognitive functions include attention, perception, making decisions, memory and speaking among other areas.
When we are young, and throughout the early years of adulthood, cognitive function is typically at its strongest. However, as we age, cognitive function naturally worsens – to an extent.
In some cases, this can result in a steep decline that results in a diagnosis of Dementia. Dementia is a syndrome that involves consistent cognitive decline, poor brain functioning and physical health issues [2].
The cause of dementia is not entirely clear, though risk factors like smoking, being overweight, poor diet, and brain problems all exist.
Past research has suggested that poor oral health – in the form of an advanced form of gum disease called periodontitis – could be linked to an increased chance of dementia developing [3].
Research into the link between various parts of oral health and dementia continues to take place – aiding scientists in finding links between the two. This new research aimed to add to this subject area.
The Research
The research was carried out by a team from the University of Exeter in England. Their findings have been published in the PNAS Nexas journal [1].
This research involved analyzing the oral microbiome. The oral microbiome refers to the collection of bacteria, viruses and fungi that live in the mouth. The make-up of the microbiome impacts our health.
To find out if the oral microbiome was linked to dementia, the researchers organized a study. The study involved 115 participants, 55 of which had mild cognitive impairment [1].
Samples were taken from the mouth of the 115 participants. These samples were then analyzed by the researchers, who were looking to see the make-up of the microbiome of the participants [1].
The researchers were especially interested in seeing if there was a difference between the samples of those with and without cognitive impairment [1].
The results were interesting. One of the main findings was that a gene called the apolipoprotein E4 (APOE4) allele was commonly found in those in the cognitive impairment group [1].
Past research has suggested that a connection between the APOE4 gene and dementia exists [4]. Therefore, this is consistent with the findings of this study.
Furthermore, a high level of porphyromonas was found in those in the cognitive impairment group. Therefore, the research suggests that porphyromonas also contributes towards dementia [1].
Conversely, the group without cognitive impairment were found to have a high level of Neisseria. Neisseria is usually a commensal bacterium, which means it contributes towards a balanced and healthy oral microbiome. Moreover, Neisseria can also convert nitrate-rich foods into nitric oxide, which fights gum disease [1].
There were a range of other types of bacteria that were found, but the above three were the most noticeable in terms of the disparity between the two groups.
What this means
These are interesting findings. They suggest that certain types of bacteria are associated with cognitive decline. Therefore, they are linked to the onset of dementia.
The authors pointed out that diet affects the oral microbiome. They have said a nitrate-rich diet can help with strong cognitive outcomes [1]. Foods in this category include green vegetables like lettuce, celery, cabbage, and some meat products like bacon, ham and sausages.
In terms of explaining the results, the researchers suggested that there are two possible links between the mouth and the brain [1].
Firstly, it could be explained by pathogenic oral bacteria entering the bloodstream and moving towards the brain, where damage occurs [1].
Or, the researchers suggest that pathogenic oral bacteria could displace nitrate-reducing bacteria – which is an important type of bacteria that helps to create the nitric oxide that the brain needs [1]. By being displaced, damage can arise.
Our actions affect the oral microbiome. When we eat sugary food and drink, it provides harmful bacteria with what it needs to flourish. But healthier foods can contribute towards a balanced microbiome.
Therefore, the findings of this research should act as a reminder of the importance of eating healthily and adopting strong oral hygiene. By doing so, we can boost our oral health and aid our cognition.
Thinking points…
[1] As mentioned above, these findings should serve as a reminder of the importance of looking after our oral health. A way of contributing towards this is to attend regular dental appointments. At an appointment, a dentist can take a look at your oral health, provide advice, and suggest treatment if needed. We recommend booking an appointment now!
[2] The findings show the importance of the oral microbiome, and everything that we put into our mouths. Take this chance to think about all the things that go into your mouth. If you have habits like biting your nails or chewing on a pen – try and stop these immediately! Similarly, try to improve your diet if possible and consume nitrate-rich foods – it can be beneficial!
What we offer at Taradale Dental
Taradale Dental is a dental clinic based in Calgary, Alberta, Canada. At our Calgary dental clinic, we provide a range of services for our patients.
We advise our patients to attend our Calgary dental clinic at least twice per year for a regular dental check-up. At these check-ups, we provide a comprehensive review of a patient’s oral health. If any problems are detected, we have many treatments available. For example, these include cavity fillings and root canals. To strengthen your oral health, we recommend brushing your teeth at least twice a day and flossing regularly.
Here at Taradale Dental, we also have some cosmetic treatments available! These include dental implants, teeth whitening and Invisalign™! Our patients find that these treatments have a positive impact on their appearance, confidence and self-esteem.
Moreover, the fees of our treatments at our Calgary dental clinic Taradale Dental are set in line with the Alberta Dental Fee Guide. This ensures transparent and fair pricing, with no hidden costs.
We hope to see you soon at our Taradale Dental clinic in Calgary! You can find out more about us by visiting our website https://taradaledental.ca/!
References
[1] L’Heureux, J. E., Corbett, A., Ballard, C., et al. (2025). Oral microbiome and nitric oxide biomarkers in older people with mild cognitive impairment and APOE4 genotype. PNAS Nexus. 4 (1): p543. DOI: https://doi.org/10.1093/pnasnexus/pgae543.
[2] NHS. (2023). About dementia. Available: https://www.nhs.uk/conditions/dementia/about/. Last accessed: 1st February 2025.
[3] Daly, B., Thompsell, A., Sharpling, J., Rooney, Y. M., et al. (2017). Evidence summary: the relationship between oral health and dementia. British Dental Journal. 223. p846-853. DOI: https://doi.org/10.1038/sj.bdj.2017.992.
[4] Sienski, G., Narayan, P., Bonner, J. M., et al. (2021). APOE4 disrupts intracellular lipid homeostasis in human iPSC-derived glia. Science Translational Medicine. 13 (583): eaaz4564. DOI: https://doi.org/10.1126/scitranslmed.aaz4564.
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