Nutrition and the prevalence of dementia in mainland China, Hong Kong, and Taiwan: an ecological study.
BACKGROUND
Western diets are associated with obesity, vascular diseases, and metabolic syndrome and might increase dementia risk in later life. If these associations are causal, those low- and middle-income countries experiencing major changes in diet might also see an increasing prevalence of dementia.


OBJECTIVE
To investigate the relationship of dietary supply and the prevalence of dementia in mainland China, Hong Kong, and Taiwan over time using existing data and taking diagnostic criteria into account.


METHODS
Estimated total energy supply and animal fat from the United Nations was linked to the 70 prevalence studies in mainland China, Hong Kong, and Taiwan from 1980 to 2012 according to the current, 10 years, and 20 years before starting year of investigation. Studies using newer and older diagnostic criteria were separated into two groups. Spearman's rank correlation was calculated to investigate whether trends in total energy, animal fat supply, and prevalence of dementia were monotonically related.


RESULTS
The supply of total energy and animal fat per capita per day in China increased considerably over the last 50 years. The original positive relationship of dietary supply and dementia prevalence disappeared after stratifying by newer and older diagnostic criteria and there was no clear time lag effect.


CONCLUSIONS
Taking diagnostic criteria into account, there is no cross-sectional or time lag relationship between the dietary trends and changes in dementia prevalence. It may be too early to detect any such changes because current cohorts of older people did not experience these dietary changes in their early to mid-life.
Department of Public Health and Primary Care, Institute of Public Health, Forvie Site, University of Cambridge, School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK.
Yu-Tzu
YT
Wu
Sunlight, Nutrition, and Health Research Center, San Francisco, CA, USA.
William B
WB
Grant
King's College London, Institute of Psychiatry, Centre for Global Mental Health, Health Service and Population Research Department, De Crespigny Park, Denmark Hill, London, UK.
A Matthew
AM
Prina
Luke International (Norway) - Malawi Office, Mzuzu, Malawi.
Hsin-yi
HY
Lee
Department of Public Health and Primary Care, Institute of Public Health, Forvie Site, University of Cambridge, School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK.
Carol
C
Brayne
D002681:China / Q000453:epidemiology; D003704:Dementia / Q000453:epidemiology* / Q000209:etiology*; D019587:Dietary Supplements; D005247:Feeding Behavior / Q000523:psychology*; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D009752:Nutritional Status; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology
China; ecological study; nutrition; prevalence of dementia