Association of oral diadochokinesis with activities of daily living in older adults: a cross-sectional observational study

Background Deterioration in tongue and masticatory functions is linked to frailty and disability-related functional abilities among older adults. This study aimed to examine the association between tongue and masticatory functions and activities of daily living (ADL) of older adults with varying levels of independence. Methods This cross-sectional study included 100 participants aged 70–85 years old. ADL was assessed using the Barthel Index (BI), and 79 and 21 participants were classified into the good ADL (BI ≥ 90) and poor ADL (BI < 90) groups, respectively. Tongue and masticatory functions were evaluated using oral diadochokinesis (ODK; /pa/, /ta/, and /ka/), tongue pressure, masticatory performance (gummy jelly test), and number of remaining teeth. Logistic regression analyses (univariate and age adjusted) and receiver operating characteristic analyses were performed. Results The ODK scores for /pa/, /ta/, and /ka/ were lower in the poor ADL group ( p < 0.05). After adjusting for age, ODK measures remained independently associated with poor ADL. Masticatory performance was lower in the poor ADL group; however, this association did not remain after adjusting for age. No correlation was observed between tongue pressure, number of teeth, and performance in ADL. The area under the curve (AUC) values for ODK /pa/, /ta/, /ka/, and masticatory performance were 0.66–0.67, indicating only modest discrimination between good and poor ADL. Conclusions ODK measures (/pa/, /ta/, /ka/) were independently associated with poor ADL status after age adjustment. However, their discriminatory ability (AUC 0.66–0.67) was limited, indicating they are not suitable as standalone screening tools without longitudinal validation.