Relationship between functional masticatory units and cognitive impairment in elderly persons.

BACKGROUND: Studies on the elderly have reported that the risk of cognitive impairment is affected by chewing difficulty. OBJECTIVE: To determine whether there is a relationship between the number of pairs of antagonist teeth that come into contact when the mouth is closed (functional masticatory units [FMUs]) and the level of cognitive impairment. METHODS: We conducted a cross-sectional observational study with 502 institutionalised White individuals older than 65 years, living in the northwest of Spain and Portugal. Through a direct visual inspection, we recorded the number of FMUs. Cognitive impairment was assessed by applying the Mini-Cognitive Examination (MCE), a test derived from the Mini-Mental State Examination. To describe the statistical relationship between the FMUs and the MCE values, a generalised linear model (GLM) was applied. We assessed the GLM predictive capacity for detecting cognitive impairment (MCE </=23) in a new study group consisting of 156 elderly individuals. RESULTS: A large number of FMUs was significantly associated with a lower probability of cognitive impairment, regardless of the nature of the contact and its location (explained deviance, 30.1%). The model's discriminatory capacity for cognitive impairment based on the FMUs was "good" (0.820). The model's predictive capacity for cognitive impairment was "acceptable" (sensitivity, 0.786; positive predictive value, 0.900; accuracy, 0.729). CONCLUSION: In White, elderly institutionalised individuals, the absolute number of FMUs is significantly related to their MCE scores.