From the mouth to the brain
A lot of research has shown that our oral health is associated with other aspects of physical health. Dental decay and in particular gum disease are linked to a number of chronic conditions including heart disease, diabetes, respiratory conditions and stroke.
More recently a number of studies have also looked at the association between oral health and cognitive decline with varied results. Few, however, have examined the relationship over a long period of time. Now a longer term study has investigated whether there’s a link between the number of teeth and cognitive decline in older Chinese adults.
The study used data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), collected between 1998 and 2011. Cognitive function was measured by a Chinese version of a validated test called the Mini-Mental State Examination.
Unsurprisingly, cognitive function was found to decline over the course of the follow up period. Regardless though, the results showed that more teeth were associated with better cognitive function. On the flip side, fewer teeth were associated with poorer cognitive function.
These results suggest that people who had more teeth showed a slower rate of cognitive decline compared to those with fewer teeth. There are a couple of plausible physiological mechanisms that might explain this association. One is the occurrence of periodontitis, a gum disease that is a common cause of tooth loss.
Periodontitis causes an inflammatory response in the body, which might circulate to the brain and aggravate what’s called neurodegeneration.
Another possible explanation is poor nutrition following tooth loss, including insufficient intake of vital nutrients and B vitamins. Poor diet is a risk factor thought to promote cognitive decline. However, there are some limitations in this study.
There may be limited generalisability due to the study being conducted in Chinese populations only. Chinese people may have different factors at play that influence their oral health including knowledge about oral health, oral diseases, access to dental care and exposure to different risk factors.
Nevertheless, the results of this study merit further research into the association between oral health and cognitive function. Other risk factors to be aware of that are possibly associated with cognitive impairment include limited education, depression, chronic disease, lack of physical activity and poor dietary habits.
Last Reviewed: 11/12/2019
Li, J., Xu, H., Pan, W., Wu, B. (2017). Association between tooth loss and cognitive decline: A 13-year longitudinal study of Chinese older adults. PLoS ONE 12(2): e0171404. doi: 10.1371/journal.pone.0171404.
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