近年来,在日本随着高龄人口的增多,有痴呆或精神病的患者也在增长着。发现痴呆患者约占65岁以上老人的4～5％,在全国估计他们的人数约有70万人。已知晓的痴呆症的病因有许多,诸如多发性脑血管梗塞,脑水肿,脑炎,脑肿瘤,脑损伤及代谢障碍等。原发性痴呆的典型分类是按照患老年前期和老年痴呆时的年龄而定的,依据的是 In recent years, with the increase of the elderly in Japan, patients with dementia or mental illness are also growing. It is found that dementia patients account for about 4% to 5% of the elderly over the age of 65, and about 700000 people are estimated in the whole country. There are many causes of dementia known, such as multiple cerebrovascular infarction, cerebral edema, encephalitis, brain tumors, brain damage and metabolic disorders. A typical classification of primary dementia is based on the age at pre-senile and dementia, based on