Cognitive function and oral perception in independently-living octogenarians

In this study, researchers hypothesized that the decline of cognitive impairment is involved in oral perceptions since its preclinical stage. The aim of this study was to examine association of cognitive function with tactile and taste perceptions in independently-living 80-year-old elderly.

The participants were community-dwelling and independently-living elderly (n=956, 80 years old) excluding those with dementia. Cognitive function was measured using the Japanese version of the Montreal Cognitive Assessment (MoCA-J) that was the assessment tool of mild cognitive impairment. Oral tactile perception was tested by oral stereognostic ability (OSA) with the test pieces comprised six shaped forms. Subjects were told they should use their tongue and palate to identify the shape. The correct identification of the shape was scored. Taste perception was evaluated by the whole mouth gustatory test with 1-ml of water solution included the four basic tastes (sweet, sour, salty and bitter). The concentration answered the taste correctly was taken as the recognition threshold.

Multiple linear regression analysis was used to examine relationships between tactile and taste perceptions and cognitive function after controlling for gender and number of teeth. P-values<0.05 were considered to be statistically significant.

The OSA score was positively associated with number of teeth. On the other hand, taste thresholds of sour, salty and bitter were significantly lower in female than males. The multiple regression analysis showed that MoCA-J score had significant positive relations to both the OSA score and taste perceptions except for sweet after controlling for other variables.

These results suggest that the decline of cognitive function was related to tactile and taste perceptions in independently-living octogenarians without dementia.