The new estimates show that there were 9.19m people with dementia in China in 2010, compared to 3.68m in 1990, and 5.69m people with Alzheimer's disease in 2010, compared to 1.93m in 1990. China had more individuals living with Alzheimer's disease in 2010 than any other country in the world.
Previous studies appear to have considerably underestimated the true burden of dementia in China, largely due to limited data availability. However, this study examined a much wider range of data sources than earlier studies, including many Chinese-language reports. The results suggest that global estimates of Alzheimer's disease might need to be revised upwards by at least 5 million cases, or almost 20%.
According to co-lead authors Dr Kit Yee Chan, Professors Harry Campbell and Igor Rudan, of the University of Edinburgh Medical School, "Of the many non-communicable diseases that need attention worldwide, dementia is predicted to have the greatest economic and social effect. The number of dementia and Alzheimer's cases in China might pose the single largest challenge to health and social care systems in terms of finding appropriate and affordable responses."
The results show that the prevalence of dementia (controlled for age) is higher for women than men, but doesn't differ significantly between urban and rural residents, with similar patterns observed for Alzheimer's disease. These findings have important policy implications because women in China have considerably longer life expectancy and constitute up to 75% of the population aged 85 years and older.
The problems presented by rising numbers of dementia cases may be exacerbated in China because of changing demographic structure and large-scale internal migration; young adults migrating from rural to urban regions are resulting in large numbers of elderly people in rural regions, especially women, living alone.
According to the authors, research and media attention in China have traditionally focused on diseases with higher case-fatality rates, such as cardiovascular disease and cancer. There is a general lack of awareness of dementia, which has important consequences – people don't seek medical help for dementia as frequently as they should, and little training is given for recognition and management of dementia at all levels of the health service.
"A response purely from strained health services is unlikely to be sufficient, and wider societal action and innovative solutions will be needed," says co-lead author Professor Wei Wang, of Edith Cowan Medical University, Australia, and Capital Medical University, Beijing, China. "Adequate resources should be provided at the national, local, family, and individual levels to tackle this rapidly growing problem, and public awareness campaigns are needed to counteract common misconceptions about dementia – including that it is not very common in the Chinese population, that it is a normal part of ageing, or that it is better not to know about it because nothing can be done about it."