A new study from Japan is the latest to find a link between gum disease and a higher risk of dementia and brain shrinkage.
A causal link has not yet been established between good dental hygiene and progressive brain death. But studies are repeatedly finding an association.
Part of brain where memories are formed
Research from the Division of Ageing and Geriatric Dentistry at Tohoku University, Japan, found that “gum disease and tooth loss were linked to shrinkage in the hippocampus”.
The hippocampus is a small, vulnerable part of the brain involved in long-term memory formation and memory retrieval. It is also part of the limbic system regulating motivation, emotion and learning.
The study
The study recruited 172 people, average age of 67, who showed no cognitive decline.
In the first phase of the study, participants had their gums examined. A probe was used to establish severity of disease. Participants also had their teeth counted. And they took memory tests to establish their cognitive health.
Their brains were scanned by MRI scans in order to measure volume of the hippocampus at baseline. They were scanned again four years later.
Hippocampal atrophy is an early characteristic of Alzheimer’s disease and other forms of dementia.
Researchers found that the degree of tooth loss and the severity of gum disease were correlated with the pace and degree of brain shrinkage.
Mild gum disease ages the brain by a year
After adjusting for age, the researchers found that “for people with mild gum disease, the increase in the rate of brain shrinkage due to one less tooth was equivalent to nearly one year of brain ageing”.
For people with severe gum disease the increase in brain shrinkage due to one less tooth was equivalent to 1.3 years of brain ageing.
“The findings suggest that retaining teeth with severe gum disease is associated with brain atrophy,”said study author Dr Satoshi Yamaguchi.
Supported by previous research
A 2021 study from New York University found that tooth loss is a risk factor for cognitive impairment and dementia. With each tooth lost, the risk of cognitive decline grows.
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