Increasing prevalence of Alzheimer's disease and other forms of dementia in China between 1990 and 2010

China is increasingly facing the challenge of control of the growing burden of non-communicable diseases. Researchers have assessed the epidemiology of Alzheimer's disease and other forms of dementia in China between 1990, and 2010, to improve estimates of the burden of disease, analyse time trends, and inform health policy decisions relevant to China's rapidly ageing population.

In the systematic review, investigators searched for reports of Alzheimer's disease or dementia in China, published in Chinese and English between 1990 and 2010.
The search returned 12642 reports, of which 89 met the inclusion criteria ( 75 assessed prevalence, 13 incidence, and nine mortality ).
In total, the included studies had 340247 participants, in which 6357 cases of Alzheimer's disease were recorded. 254367 people were assessed for other forms of dementia, of whom 3543 had vascular dementia, frontotemporal dementia, or Lewy body dementia.

In 1990 the prevalence of all forms of dementia was 1.8% at 65-69 years, and 42.1% at age 95-99 years.
In 2010 prevalence was 2.6% at age 65-69 years and 60.5% at age 95-99 years.

The number of people with dementia in China was 3.68 million in 1990, 5.62 million in 2000, and 9.19 million in 2010. In the same period, the number of people with Alzheimer's disease was 1.93 million in 1990, 3.71 million people in 2000, and 5.69 million in 2010.

The incidence of dementia was 9.87 cases per 1000 person-years, that of Alzheimer's disease was 6.25 cases per 1000 person-years, that of vascular dementia was 2.42 cases per 1000 person-years, and that of other rare forms of dementia was 0.46 cases per 1000 person-years.

Investigators retrieved mortality data for 1032 people with dementia and 20157 healthy controls, who were followed up for 3-7 years. The median standardised mortality ratio was 1.94:1.

In conclusion, the analysis suggests that previous estimates of dementia burden, based on smaller datasets, might have underestimated the burden of dementia in China.
The burden of dementia seems to be increasing faster than is generally assumed by the international health community. ( Xagena )

Chan KY et al, The Lancet 2013; 381: 2016-2023


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