Previous research has pointed to an association between not having teeth and a higher risk of cognitive decline and dementia. One reason might have to do with inflammation — inflammation is a well-established risk factor, and at least one study has linked gum disease to a higher dementia risk. Or it might have to do with the simple mechanical act of chewing, reducing blood flow to the brain. A new study has directly investigated chewing ability in older adults.
The Swedish study, involving 557 older adults (77+), found that those with multiple tooth loss, and those who had difficulty chewing hard food such as apples, had a significantly higher risk of developing cognitive impairments (cognitive status was measured using the MMSE). However, when adjusted for sex, age, and education, tooth loss was no longer significant, but chewing difficulties remained significant.
In other words, what had caused the tooth loss didn’t matter. The important thing was to maintain chewing ability, whether with your own natural teeth or dentures.
This idea that the physical act of chewing might affect your cognitive function (on a regular basis; I don’t think anyone is suggesting that you’re brighter when you chew!) is an intriguing and unexpected one. It does, however, give even more emphasis to the importance of physical exercise, which is a much better way of increasing blood flow to the brain.
The finding also reminds us that there are many things going on in the brain that may deteriorate with age and thus lead to cognitive decline and even dementia.
 . Chewing Ability and Tooth Loss: Association with Cognitive Impairment in an Elderly Population Study. Journal of the American Geriatrics Society [Internet]. 2012 ;60(10):1951 - 1956. Available from: http://onlinelibrary.wiley.com/doi/10.1111/j.1532-5415.2012.04154.x/abstract