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North West Regional Health

Tooth Loss And Memory Loss May Be Correlated

The European Journal of Oral Sciences published a peer-reviewed, cross-sectional study, which found a significant connection between memory loss and tooth loss. This study would be instrumental; corroborating other research conducted on the link between dental and mental health, including a massive study that was published last year that followed 5,500 elderly folks over an 18-year span. (That research, from University of California, found that subjects who brushed less than once a day were up to %65 more likely to develop dementia than subjects that brush three or more times a day.)

Other studies have found that associated gum disease with Alzheimer’s. Scientists believe bacteria that cause gum disease may be gaining exposure to the brain, causing inflammation and wreaking havoc on cognitive function.



The study, funded by the Swedish Council for Social Research, involved 273 test subjects ages 55-80. The volunteers were participating in an ongoing cohort study on cognitive memory. The selected individuals were subjected to cognitive tests, a physical, and an oral examination.

Regarding cognitive abilities the researchers measured:

Semantic Memory

Episodic Memory

Working Memory

Visuo-Spatial Skills


The researcher’s oral examination took data on:

Dental fillings, caries, prosthetic treatments etc.

Periodontal diseases (oral conditions which affect tissue near teeth)

Occlusion, or “how your upper and lower rows of teeth fit together”

And of course, the number of remaining teeth


Finally, the research team took note of some basic statistical criteria including but not limited to:

Education attained




Living environment

Medical history




On average, the subjects were missing ten or more teeth, mostly molars.

“In line with the stated hypothesis, the number of natural teeth was positively associated with performance on episodic memory, recall as well as recognition,” the Scandinavian scientists reported “Alone, number of natural teeth could account for 20 per cent of the variance in episodic recall, 15 per cent of the variance in episodic recognition, and 14 per cent of the variance in semantic memory.”

Obviously, several correlations were determined. Younger subjects scored higher on cognitive tests, better educated subjects did as well, so did people with people in better living environments and in better occupations. These factors accounted for about between 11 and 52 percent of the variance in cognitive scores.

On the other hand, many traits the doctors tested for appeared to have no significant association with memory loss. These included cardio-vascular disease history, stress levels, eye disease and even head injuries.


The team that conducted the research said that “…the presence of natural teeth seems to have an impact on cognitive function…”


A study of this kind cannot determine causation. We cannot definitively say: “poor dental hygiene causes cognitive disrepair in older demographics” Any number of factors could be causing the mental performance issues:

Chewing increases blood flow to the head. A lack of teeth would invariably lead to a reduction in chewing which could lead to less blood reaching the brain and preventing the hippocampus from firing off on all cylinders. Even self-imposed dietary restrictions caused by chewing impairment could theoretically be the cause of mental performance problems.

Perhaps lack of education and environmental factors contribute to poor hygiene contribute which in turn contributes to tooth loss. Those same factors may the driving factor behind memory loss. Maybe the people who don’t value hygiene, also don’t value intellectual stimulation.


What’s more, a study of this size cannot be used to generalize the human population. It’s important to remember the distinction between correlation and causation.

With that in mind, you’d probably be wise to start flossing now and then.