Longitudinal Association Between Self-Reported Chewing Difficulty and Depression Among Older Japanese Adults Using Data From the Longevity Improvement and Fair Evidence Study

Introduction Depression in older adults is linked to adverse health outcomes such as reduced daily living activities and decreased quality of life. Although studies show a connection between depression and oral health issues like chewing difficulty, the specific links between subjective chewing ability, the number of teeth, and the onset of depression remain underexplored. This study aimed to investigate the relationship between self-reported chewing ability and the onset of depression among an elderly population aged 65 years or older in Japan. Methods Using claim data from Japan's National Health Insurance, we conducted a longitudinal study of 23,417 subjects aged 65 years and older. These subjects participated in specific health checkups and visited a dental office within one year (April 2018 to March 2019). Participants who reported, "Sometimes it is difficult to chew due to dental problems" or "I can hardly chew" were identified as having chewing difficulties. The number of teeth was estimated using dental care claims data. We employed multivariate logistic regression analyses, with new diagnoses of depression from April 2019 to March 2020 as the dependent variable and self-reported chewing difficulty and the number of teeth as independent variables. Results Out of the total 23,417 participants, 462 (2.0%) received a new diagnosis of depression during the one-year follow-up period. After adjusting for covariates, self-reported chewing difficulty was significantly associated with the onset of depression (odds ratio = 1.26; 95% confidence interval: 1.00-1.58). However, there was no significant association between the number of teeth and depression. Conclusion Among individuals aged 65 years and older, self-reported chewing difficulty has a significant impact on the risk of developing depression. This study underscores the importance of addressing oral health, particularly chewing ability, to mitigate the risk of depression.