Longitudinal association of oral function and dementia in Japanese elderly people

The relationship between oral function and dementia was examined in 7384 elderly people (age ≥ 75 years) who visited a dental clinic in Gifu, Japan. Participants without dementia in a baseline survey in April 2018 were followed until March 2021. As oral functions, chewing function, tongue and lip function, and swallowing function were assessed by self-administered questionnaire, by oral diadochokinesis test, and by repetitive saliva swallowing test, respectively. The presence of systemic diseases was based on data obtained from the National Database of Health Insurance of Japan (NDB). At follow-up, 415 (6%) participants were diagnosed with dementia. Multivariate logistic regression analyses showed the presence of dementia at follow-up was associated with female (odds ratio [OR], 1.386; 95% confidence interval [CI], 1.117–1.719), elderly (OR, 1.078; CI, 1.056–1.101), regular dental checkups (absence; OR, 1.452; CI, 1.180–1.788), brushing frequency ≥ twice/day (absence; OR, 1.510; CI, 1.194–1.911), decayed teeth (presence; OR, 1.328; CI, 1.071–1.648), swallowing function (poor; OR, 1.484; CI, 1.135–1.939) at baseline. It was found that poor swallowing function was associated with the future onset of dementia.