The Journal of the American Geriatrics Society recently published a study that showed people aged 60+ who had none of their own teeth performed worse in memory and walking tests than people who still retained their own teeth.
Even after adjusting for a myriad of variation in behavior, like sociodemographics, existing health conditions, physical health, smoking, drinking, depression, and socioeconomic status, people who didn’t have their own teeth still performed slower than those with teeth.
According to the lead author, Dr. Georgios Tasakos, “tooth loss could be used as an early marker of mental and physical decline in older age, particularly among 60-74 year olds…excessive tooth loss presents an opportunity for early identification of adults at higher risk of faster mental and physical decline later in their life.”
Now, this doesn’t mean that if you are missing a few teeth you should worry about suddenly developing mental problems—it’s just a good indicator of decline that should be noted in older adults. It’s just another reason to keep up healthy oral habits life-long.
You can read more about the study here - https://www.sciencedaily.com/releases/2014/12/141218210023.htm