Is losing teeth related to losing your memory?

A recent study, published online by the European Journal of Oral Sciences, suggests that there is a mild connection between the amount of teeth in an elderly person's mouth and the extent of their memory.

Researchers from universities in Norway and Sweden randomly selected 273 people between the ages of 55 and 80 for an ongoing cohort study. Participants had their mouths examined, gave self-reported health assessments and were put through a battery of cognitive tests. People with possible dementia or other neurological conditions were excluded from the study, reports British medical website National Health Service.

"In line with the stated hypothesis, the number of natural teeth was positively associated with performance on episodic memory, recall, as well as recognition," write the authors of the paper.

On average, participants had approximately 22 of 32 natural teeth. Molars were most likely to be missing.

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The researchers hypothesis the association between teeth and cognitive function may be due to a lack of sensory input from nerves connected to teeth and surrounding tissues, which send signals to the brain during chewing. If there are less teeth, presumably there will be less signals. They suggest that chewing increases blood flow to the brain.

While it may seem obvious that other factors such as age and education are more closely related to cognitive function, the researchers did account for a number of confounding factors. Those variables included: age, education, gender, occupation and living conditions.

Despite these factors, teeth loss was still statistically related to performance on cognitive tests.

Researchers found that while age and education were significantly associated with performance on cognitive tests, the number of natural teeth was also associated with better performance on episodic recall and recognition tests, as well as on the vocabulary test.

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While age, length of education, gender, occupation and living conditions accounted for the majority of the variance in cognitive test scores (11-52 per cent), the number of natural teeth accounted for 3-4 per cent of the variability in test scores, reports National Health Service.

The authors conclude, "The presence of natural teeth seems to have an impact on cognitive function."

The study was funded by the Swedish Council for Social Research, Västerbotten County Council and other organizations throughout Sweden.