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Cognitive Functions of oldest-old: before 100 years old and after

Hiroki Inagaki, Ph.D.

Researcher (Prevention and Intervention of Dementia and Depression)

The elderly population of Japan continues to increase, and resultantly, the life expectancy in the country has also increased. Against this background, "a society in which everyone can live longer" is being realized. In this context, it would be pertinent to examine the ways in which old age affects cognitive functions. To this end, we examined the cognitive functions of centenarians who lived until limit of life expectancy.
Cognitive functions are a very important aspect of functionality. They are also a key factor in the context of "Successful Aging". On the other hand, cognitive dysfunction is a symptom of dementia, and many aspects of cognitive functions are also known to deteriorate with age.
In Tokyo Centenarian Study, we examined the cognitive functions of cognitively intact centenarians using the Mini-Mental State Examination method (MMSE). The total score achieved by centenarians who participated in this study was lower than the scores achieved by the so-called "younger elderly." While the test showed that the overall functionality of the centenarians had decreased significantly, not all aspects of their cognitive functions were affected to the same extent. Functions such as orientation and memory declined, whereas aspects such as linguistic capability and the capacity for praxis did not deteriorate significantly; in fact, their scores for these functions were similar to the scores achieved by the younger elderly. In comparison with elderly people with mild cognitive disabilities, centenarians' long-term memory and orientation were found to be normal, although they had deteriorated to a considerable extent.
In order to prepare for the "super-aged society," it is important to consider lifestyles as well as system of society to accommodate elderly people diagnosed with dementia. In other words, it is important to create "dementia-friendly communities" to enable the elderly to live with hope and dignity, even after the onset of dementia.