Bad bacteria from the mouth can damage the brain, leading to an increased risk of dementia, according to a new study.
Researchers from the University of Exeter analysed oral swabs from people showing signs of mild cognitive impairment compared to those showing no decline in brain function. The results suggest that oral bacteria could impact brain health both positively and negatively.
Firstly, the researchers said that harmful bacteria entering the bloodstream could potentially damage the brain. Greater levels of Porphyromonas bacteria were more common in individuals with memory problems.
The study also found that an imbalance of good and bad bacteria affected the body’s ability to process nitrates found in a vegetable-rich diet. These chemicals are crucial for brain communication and memory, so the authors predict that this could lead to poorer brain function. They found that the bacteria group Prevotella was common in those with low nitrate levels.
On the other hand, people whose mouths contained large amounts of Neisseria and Haemophilus bacterias were found to have improved cognitive function. They displayed better memory, attention and ability to perform complex tasks.
‘Bacteria in the mouth could be part of a solution to prevent dementia’
Lead author Dr Joanna L’Heureux said: ‘Our findings suggest that some bacteria might be detrimental to brain health as people age. It raises an interesting idea for performing routine tests as part of dental check-ups to measure bacterial levels and detect very early signs of declining brain health.’
While most adults experience some loss of memory and brain function as they age, deterioration above normal levels is considered mild cognitive impairment. Around 15% of older adults fall into this category, which is considered the greatest risk factor for dementia and Alzheimer’s disease.
The researchers hope that the study might help in developing preventive action against dementia. Co-author Professor Anne Corbett said: ‘The implication of our research is profound. If certain bacteria support brain function while others contribute to decline, then treatments that alter the balance of bacteria in the mouth could be part of a solution to prevent dementia.
‘This could be through dietary changes, probiotics, oral hygiene routines, or even targeted treatments.’
Published in PNAS Nexus the study analysed data from 110 participants over the age of 50.
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