If you are able to bite into an apple, you are more likely to maintain mental abilities according to new research.
Research shows several possible contributors such changes, with several studies demonstrating an association between not having teeth and loss of cognitive function and a higher risk of dementia.
A potential reason for this could be that few or no teeth makes chewing difficult, which leads to a reduction in the blood flow to the brain. Even so there have been no direct investigation into the significance of chewing ability in a national representative sample of elderly people.
Researchers at the Department of Dental Medicine and the Aging Research Center (ARC) at Karolinska Institutet and from Karlstad University in Sweden have looked at tooth loss, chewing ability and cognitive function in a random nationwide sample of 557 people aged 77 or older. The researchers found that those who had difficulty chewing hard food such as apples had a significantly higher risk of developing cognitive impairments. The researchers explored this correlation further and it remained even when controlling for education, sex, age, and mental health problems. Whether chewing ability was sustained with natural teeth or dentures also had no bearing on the effect.
It would be interesting to determine better what else is at play here and why not having many teeth can lead to dementia risk.
Source: Duangjai Lexomboon, Mats Trulsson, Inger Wårdh & Marti G. Parker. Chewing Ability and Tooth Loss: Association with Cognitive Impairment in an Elderly Population Study. Journal of the American Geriatrics Society, 2012