I. Introduction
In recent years, lifespan has increased in Japan, and it is the aging society with the highest population aging rate among advanced countries [1]. According to Statistics Bureau of Japan, the population over 65 years old exceeds 35 million, the ratio is 27.7%, and it is the highest in the history [2]. On the other hand, Japan is trending of nuclear families, the increase in the number of elderly people who live alone aged over 65 for both men and women. According to the transition of the number of households and future estimation of the elderly people listed in the white paper on annual report on the aging society in 2017 edition, it is estimated that the total number of them is approximately 6.7 million in 2020 [3]. In addition, future estimates of the dementia patients will exceed 6 million in 2020 [1]. And future estimates of the prevalence rate of elderly people aged over 65 expected to be about one in five in 2025 [1]. It is common that early detection of dementia is often suspected by families living together noticed changes in the behavior of the elderly. However, in the case of the elderly people living alone, there are risk that the symptoms may progress without being aware anyone because they are no one who live together. With dementia, the earlier treatment can be expected to be effective, because it can delay the progression. Therefore, it is desirable to detect initial symptoms. The one of initial symptom of dementia has “Decrease of Living Motivation”, also known as “Apathy”. It has proved from previous study [4] that a living motivation has a positive correlation with activities of daily living. The activities of daily living are the minimum behavior necessary to live daily life, like behavior of movement, eating, excretion, bathing, sleeping, etc. It is used as an important indicator for measuring the physical ability and daily life level of elderly and disable people.