According to the popular spot check method we investigated 14,684 partial community persons. The screen instrument used was the MMSE. Positive cases were through ADL, HDS and detailed psychical examination by two doctors according to the CCMD-2 to establish a definite diagnosis. Differential diagnosis between AD and MID was carried out according to HIS result. A total of 1448 persons were over 60 years, which amounted to 9.98% of the entire population. Of a total of 672 men and 776 females, 13 suffered senile dementia, which made up 0.995% of the aged. There were seven MID (5 males, 2 females) and six AD (2 males, 4 females). Family histories showed that one AD had the same symptoms as her twin sister. Two AD and four MD drank Chinese spirit 2-4 liang per day for 20 years, 80% of patients were nursed by the son or daughter-in-law, but they believed wrongly that 'It is necessary to cure the old'. Six of 13 had a long period of drinking history, four of six for MID. This has shown that dementia partly relates to drink especially for MID. Early case can be detected through daily life activities such as buying food, playing cards etc. Activities of daily living may avoid the pseudo-positive which is caused by educational level.