Association between masticatory function and depression in older adults: Results from NHANES 2009 to 2018

Abstract Aim Depression is prevalent among older adults. Although the number of missing teeth is considered to be associated with depression, the relationship between masticatory function, which is usually indicated by functional tooth units (FTUs), and depression in older adults remains unclear. Materials and Methods This study used data from the National Health and Nutrition Examination Survey (NHANES) 2009–2018. The number of FTUs was defined as pairs of opposing natural and artificial teeth. Depression was accessed using the Patient Health Questionnaire (PHQ‐9), and participants who scored ≥10 on PHQ‐9 were diagnosed with depression. Logistic regression analyses, propensity score matching (PSM) analyses and subgroup analyses were conducted to assess the association between FTU and depression. Results The analysis included 5764 individuals over 60 years. An association between FTU and the risk of depression among older adults was detected (odds ratio [OR] = 0.951, 95% confidence interval [CI] 0.915–0.989), suggesting protective roles of more FTUs. Significant increase in the risk of depression in 0 ≤ FTUs ≤ 3 was observed compared with 10 ≤ FTUs ≤ 12 (OR = 1.819, 95% CI 1.157–2.858). However, no significant increase in the risk of depression in 4 ≤ FTUs ≤ 9 was found. After PSM, significant increase in the risk of depression in 0 ≤ FTUs ≤ 3 was still detected compared with 4 ≤ FTUs ≤ 12 (OR = 1.484, 95% CI 1.030–2.136). Subgroup analyses demonstrated consistent results in all subgroups, except for individuals aged 76–80 and drinking regularly. Conclusions The findings suggested the association between impaired masticatory function and the risk of depression among older adults. Longitudinal studies are needed to elucidate the role of masticatory function impairment in the development of depression further.