Researchers looked at 273 people ageing 55 and older, and found a modest but significant relationship between a person's number of natural teeth and his or her performance on memory tests.

The link held when researchers took subjects' ages into account. In other words, it wasn't simply that both teeth and memory abilities tend to disappear with age, 'LiveScience' reported.

While the reason for the link isn't entirely clear, the new findings are in line with previous animal and human studies, suggesting that the presence of natural teeth has an impact on cognitive function, and having fewer teeth may be regarded as a risk factor for memory problems in the elderly, according to the researchers.

Animal studies have shown that rats whose teeth were pulled out showed memory and learning problems. The rats that had lost more teeth showed higher neuronal loss, and more damage to the hippocampus, a part of the brain involved in memory formation.

It is possible that loosing natural teeth reduces sensory signals that teeth send to the brain, affecting its functions, including memory, the researchers said. Natural teeth send signals to the brain via a nerve that is responsible for sensation in the face, and for motor functions, such as biting and chewing.

Researchers said it is possible that a common factor could be responsible for the link between teeth and memory. For instance, gum infections that could lead to tooth loss may also cause inflammation, which may, in turn, cause neuronal death and memory loss, they said.

Researchers accounted for other factors that can affect memory — such as participants' years of education, type of occupation and medical history — but the link between teeth and memory remained significant.

Study participants had an average of 22 natural teeth, almost one-third less than a complete set of human teeth, which may have caused them to avoid or eat less of certain foods that contain the nutrients necessary for maintaining a strong memory, researchers said.

The study will be published in the European Journal of Oral Sciences.

(Agencies)

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