Smoking and Alzheimer's disease among Mongolian and Han Chinese aged 55 years and over living in the Inner Mongolia farming area of China.

Residents aged 55 years or older from 27 communities and two settlements in Xilingol League of Inner Mongolia were selected for participation in an Alzheimer's disease epidemiological investigation from June 2008 to June 2009, including 3 259 Mongolians and 5 887 Han Chinese. The Mongolian subjects in the Alzheimer's disease group were at age of 55 years or older (on average), and more of them were male, illiterate and/or had a history of coronary artery disease and/or diabetes compared with the Mongolian subjects in the non-Alzheimer's disease group. The Han Chinese subjects in the Alzheimer's disease group were at age of 55 years or older (on average) and more of them were women, illiterate and/or had a history of coronary artery disease, and less of them had a history of alcohol consumption compared with the non-Alzheimer's disease group. Non-conditional multivariate stepwise logistic regression identified that male gender, increasing age and having a history of diabetes and/or coronary heart disease were associated with higher odds of Alzheimer's disease among Mongolians while having an educational background was associated with lower odds (OR = 0.259, 95%CI 0.174-0.386). Among the Han Chinese subjects, male gender, increasing age and having a history of coronary heart disease and/or hypertension was associated with higher odds of Alzheimer's disease, while having an educational background was associated lower odds (OR = 0.271, 95%CI 0.192-0.381). The results also indicated that extremely heavy smoking may be a risk factor for Alzheimer's disease in Mongolian males aged over 55 years. There was no significant difference in smoking habits between the Mongolian and Han Chinese subjects with Alzheimer's disease.