The increase of dementia patients is one of the problems caused by aged population in Japan. This study analyses balance and trend in use of present, past and future tenses in conversation among old- er adults in order to investigate the relationship in mental time travel of the speaker and symptom of cog- nitive decline and dementia. The ability to travel mental time has been evolved in humans in particular, and can be observed in grammatical structure of the sentences, especially as a tense. Therefore, there was a correlation to mental time and use of tense in conversation. The results suggest that healthy older adult tends to use present tense frequently.

We analyzed the parts of speech, repeated noun and clause from the speech of older adults in Coimagination Method, and examined correlation between cognitive function and linguistic features. Japanese version of MoCA (Montreal Cognitive Assessment) was used for cognitive function assessment of 18 older adults. Repetition clause rate in the sentences increased with the decrease of MoCA score in Coimagination Method. Correlation was not found for the frequency of fillers and other index of repetition rate in the experiment.

In the walking session of Conversation via Coimagination Method, We take some pictures as subject to use conversation. We experimented to verbalize the working of human mind to acknowledge the point of view by ourselves, memorize and remember the subject at the time of taking a picture.