Period, birth cohort and prevalence of dementia in mainland China, Hong Kong and Taiwan: a meta‐analysis

Abstract

ObjectiveThere have been dramatic societal changes in East Asia over the last hundred years. Several of the established risk factors could have important period and cohort effects. This study explores temporal variation of dementia prevalence in mainland China, Hong Kong and Taiwan taking study methods into account.MethodsSeventy prevalence studies of dementia in mainland China, Hong Kong and Taiwan were identified from 1980 to 2012. Five period groups (before 1990, 1990 ∼ 1994, 1995 ∼ 1999, 2000 ∼ 2004 and 2005 ∼ 2012) and five birth cohort groups (1895 ∼ 1909, 1910 ∼ 1919, 1920 ∼ 1929, 1930 ∼ 1939 and 1940 ∼ 1950) were categorised using the year of investigation and 5-year age groups. Pooled prevalence by age, period and birth cohort groups was estimated through meta-regression model and meta-analysis taking diagnostic criteria and age structure into account.ResultsAfter adjusting for diagnostic criteria, the study age range and age structure, the prevalence of dementia in the older population aged 60 years and over fluctuated across periods but not reaching significance and were estimated as 1.8%, 2.5%, 2.1%, 2.4% and 3.1% for the five periods from pre-1990 to 2005 ∼ 2012. A potential increasing pattern from less to more recent birth cohort groups was found in the major studies using older diagnostic criteria with wider differences in the age groups over 70 years.ConclusionsThis study found no significant variation across periods but suggested a potential cohort effect. The influence of societal changes might moderate early life experiences across different generations with substantial impact on mental health in older age. © 2014 The Authors. International Journal of Geriatric Psychiatry published by John Wiley & Sons Ltd.

The economic burden of dementia in China, 1990–2030: implications for health policy

“…In China, which has the largest population of people with dementia, the prevalence of dementia appears to have increased steadily between 1990 and 2010 2 , 3 . However, this trend might be partly attributed to temporal variations in the methods used to estimate such prevalence 4 . The results of a national survey in 2008–2009 indicated that dementia was more common in rural areas than in urban settings 5 .…”

Prevalence of dementia in East Asia: a synthetic review of time trends

“…However, this increasing trend could be a function of changes in study designs and methodological factors such as diagnostic criteria, which have been revised considerably in the past 30 years. A systematic review taking these into account did not show significant changes, and that there is major heterogeneity between studies (Wu et al ., 2014). Prevalence estimates in the studies using newer diagnostic criteria such as the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and 10/66 diagnostic algorithm are systematically and significantly higher than those using older diagnostic criteria such as the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM-III), Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised (DSM-III-R), Chinese Classification of Mental Disorders (Wu et al ., 2013).…”

“…Considering the rise of non-communicable diseases in East Asian countries, the prevalence of dementia could indeed increase in the next few decades. This includes China, the country with the largest population in the world, even though the trend of prevalence has not significantly increased over the last 30 years (Wu et al ., 2014). …”

Dementia: Time trends and policy responses

“…The authors report a substantial increase of dementia prevalence in mainland China with a doubling of age-specific prevalence from 1990 to 2010 [32,34]. However, this pattern could be largely attributed to variation of study designs and methodological factors as these are significantly related to heterogeneity of prevalence studies in China [35,36]. Higher prevalence was found in the recent studies using newer diagnostic criteria (DSM-IV and 10/66 algorithm) than those using older diagnostic criteria (DSM-III, DSM-III-R and CCMD).…”