Dementia of oldest old age

Koji Hori, Toshiyasu Asaoka, Tatsuro Oda,
Reiko Oyamada, Itaru Tominaga, Toshiya Inada

Showa University Northern Yokohama Hospital, Department of Psychiatry

    The oldest old population (age of 85 and over) is remarkably increasing in number and aging is the major risk factor for dementia. Therefore, the problem of dementia in this generation is becoming more and more important. However, there were few studies concerning the clinical features of dementia in the oldest old. Therefore, we reviewed the dementia of oldest old (at the age of 85 and over). The features and the treatment of dementia in very old people should be different from those in younger people if there are any clinical features specific to the dementia in very old people.
    It was reported that an exponential increase in the prevalence of dementia with age. However, it is indicated that in spite of the exponential increase of prevalence rate of dementia up to the age of 85 years, the rate of prevalence decelerates between 80 and 84 and that around the age 95 the prevalence rate of dementia levels off at about 40%. However, at the age of over 100, almost all people were reported to be demented. This indicates that aging might be considered again to be an important risk factor for precipitating cognitive impairment in the oldest old. It is interesting to know that in the oldest old age group, not only Alzheimer’s type dementia but also limbic neurofibrillary tangle dementia or senile dementia of the neurofibrillary tangle type appear in neuropathological findings. The later may be diagnosed as Alzheimer’s type dementia in clinical setting.
    There were few studies concerning the clinical features of dementia in the oldest old. In early onset Alzheimer’s disease group, memory disturbance and disorientation are more severe and wandering and pacing, hoarding and emptying drawers or closets are more frequent than those in senile dementia of Alzheimer’s type. On the other hand, “impaired long-term memory” are less severe in the oldest old demented group than in senile dementia of Alzheimer’s type. “Impaired wakefulness” and “confusion” are more severe and “waking up and wandering at night” is also more frequent in the oldest old demented group than in senile dementia of Alzheimer’s type. These characteristics suggest that the clinical features of dementia in early onset Alzheimer’s disease group were quantitatively different from those of senile dementia of Alzheimer’s type. On the contrary, the clinical features of dementia of oldest old are characterized by disturbance of sleep-wake pattern and are qualitatively different from those of senile dementia of Alzheimer’s type.

Address correspondence to Dr. Koji Hori, Showa University Northern Yokohama Hospital, Department of Psychiatry (35-1, Chigasaki-chuo, Tsujukiku, Yokohamashi, Kanagawa 224-8503, Japan)