Relationship between cognitive function and mastication in elderly females.

In Japan, the elderly population suffering from dementia is rapidly increasing. Several animal studies have indicated a relationship between reduced masticatory function in the elderly subject and cognitive impairment. However, epidemiological studies examining this have been scarce. Using an epidemiological approach, the present study investigated this relationship in 44 females with and 44 without dementia, all aged over 65 years. Age and basic activities of daily living, such as walking, eating, excreting, bathing and dressing, were matched in the two groups. Cognitive impairment of the subjects was measured using the revised Hasegawa Dementia Rating Scale. Masticatory function was assessed in terms of the number of teeth present, maximum bite force, occlusal contact area, and mastication score. The number of teeth present in cognitively normal subjects was significantly higher than in cognitively impaired subjects (P < 0.05). In addition, maximum bite force, occlusal contact area, and mastication scores of cognitively normal subjects were significantly higher than those of cognitively impaired subjects (P < 0.01). These results suggest that masticatory function in the elderly person is associated with cognitive status.