The changes of cognitive function and masticatory function for four years between community-dwelling elderly people in Japan: An observational study

Aim: Masticatory and cognitive function in independent elderly people were traced for 4 years and the changes in both functions were analyzed. Materials and Methods: The study type is an observational study for 4 years. Subjects of 65 and above were selected by simple random sampling method and measured cognitive function (MMSE), oral status, and masticatory test at the first year, after 2 years, and after 4 years. The subjects were divided into three groups: subjects with maintained cognitive function for 4 years (n = 12), subjects with declined cognitive function on the time course (n = 15), and subjects with impaired cognitive function for 4 years (n = 4). The data of oral condition in each group were analyzed by Kruskal–Wallis test and Dunn–Bonferronias post hoc test (age, MMSE, masticatory ability). Statistical significance was defined at P < 0.05. Results: Remarkable change of oral status was not detected. With cutoff value as 100 mg/dL, we analyzed the combined masticatory and cognitive function changes. The subjects who had declined cognitive and maintained masticatory function were 22.6% and the subjects who had declined masticatory and maintained cognitive function were 6.5%. The rest of those independent elderly people shows various patterns. Conclusion: It was observed that the subjects who had declined cognitive and maintained masticatory function were much more than the subjects who had declined masticatory and maintained cognitive function.