Mid-life and late-life vascular risk factors and dementia in Korean men and women.

Dementia is one of the most important neurological disorders in the elderly population. The significance of vascular risk factors for dementia remains controversial. This study aimed to determine the effects of vascular risk factors, such as blood pressure, diabetes and smoking in the mid-life or the late-life on dementia risk. The data in this prospective cohort study came from 3252 dementia events occurring over 14 years among 848,505 Koreans aged 40-95 years insured by the National Health Insurance Corporation who had a biennial medical evaluation during 1992-1995. Data on clinical dementia during the period 1993-2006 were examined in relation to vascular risk factors. The age adjusted incidence per 100,000 was 31.9 for men and 45.0 for women, respectively. In multivariate Cox proportional hazard models, diabetes increased the risk of either dementia in Alzheimer's disease or vascular dementia in men and women, controlling for age, hypertension, total cholesterol, alcohol drinking, and smoking. Hypertension also increased vascular dementia in both men [Hazard ratio (HR)=2.6, 95% confidence interval (CI)=1.7-3.8] and women (HR=2.3, 95%CI=1.6-3.3). The association of hypertension or diabetes on risk of vascular dementia, however, among the group aged older than 65 was attenuated but remained as significant in men. There was no interaction between hypertension and diabetes on the risk of dementia. This study demonstrates that diabetes and hypertension increased the risk of vascular dementia. Treatment for these risk factors may reduce the risk of vascular dementia.