Objectives To investigate the cognitive function status of elderly who were living in nursing houses in northern rural part of China and to explore its related factors.

Methods Subjects of study were elderly living in nursing houses of Lao Ting County. The survey was conducted in winter of 2012 using standardised CVD epidemiological investigation methods. The items of investigation included questionnair, physical examination and blood sample test. After excluding congenital retarded, deaf, and blind cases, totally 381 participants aged ≥ 50 yr with complete data collection were used for data analysis. Assessment of cognitive function was using MMSE table. The diagnostic criteria of hypertension was SBP ≥ 140 or DBP ≥ 90 mmHg or taking anti-hypertensive drugs in the last two weeks. According to educational levels all participants were divided into three groups:lliteracy (139), primary school (196), middle school and above (46).

Results The average age was 69 ± 9 yr. The SSME score was 15.1 ± 7.8, 19.1 ± 7.6 and 24.6 ± 7.0 for illiteracy, primary school, middle school and above group respectively. The score of MMSE by age group was as follows: 50-59 y 18.5 ± 9.0, 60-69 y 19.3 + 8.0, 70-79 y 18.8 + 7.5,≥ 80 y 13.2 ± 7.6. The prevalence of hypertension was 73.8%, 85.1%, 88.0% and 88.6% for 50-59 y, 60-89 y, 70-79 y and > = 80 y age group respectively. The percentage of MMSE score < 20 was 67.6, 44.9, 19.6 for illiteracy, primary school, middle school and above group respectively. Multi-regression analysis showed that MMSE score was positively related to male sex, age and serum total cholesterol (all p < 0.05), negatively related to educational levels (p < 0.001).

Conclusions Lower level of education is more prone to have cognitive dysfunction for elderly of nursing houses in this region. The level of cognitive function was significantly decreased in very elderly population (age > = 80 yr). Serum total cholesterol may be a related factor for cognitive dysfunction. More studies are needed.