[Study on the incidence and risk factors of dementia in elderly residents from communities in Beijing].

Objective: To study the incidence of dementia and its risk factors among the elderly living in the community of Beijing.

Methods: A sample of 2788 elderly residents from Beijing were investigated regarding the incidence of dementia which was diagnosed using two-stage method in 1997. In the first stage, questionnaire was filled, including MMSE checked up. In the second stage, all the elderly who had lower MMSE score and some with normal MMSE score were examined by neurologists. The clinical diagnosis of dementia was set up by two neurologists according to the criteria of DSM-III-R and NINCDS-ADRDA. The same sample was followed up on 2000 and 2004 by the same way, with the overall time for following-up as 7.25 years.

Results: 171 dementias cases were diagnosed among the 2788 elderly in 1997. At the end of the survey, another 180 new cases developed. The average weighted incidence was 0.84/100 person year, adjusted by age (it's same followed), with 0.64/100 person year in males and 1.01/100 person years in females. The incidence of vascular dementia was 0.35/100 person years, with male as 0.39/100 person year and female as 0.32/100 person years. The incidence of dementia was increasing with age, but decreasing with time of education by Multinomial Logistic Regression Analysis. Old age and illiterate appeared to be the risk factors for dementia. People with stroke history and elevated systolic blood pressure were risk factors for vascular dementia.

Conclusion: The incidence of dementia in the elderly in Beijing was higher than in other areas of China. Old age and illiterate were risk factors for dementia. Being male, illiterate, with stroke history and elevated systolic blood pressure were risk factors for vascular dementia.