Yu-Tzu Wu

Dementia in western Europe: epidemiological evidence and implications for policy making

Dementia is receiving increasing attention from governments and politicians. Epidemiological research based on western European populations done 20 years ago provided key initial evidence for dementia policy making, but these estimates are now out of date because of changes in life expectancy, living conditions, and health profiles. To assess whether dementia occurrence has changed during the past 20-30 years, investigators of five different studies done in western Europe (Sweden [Stockholm and Gothenburg], the Netherlands [Rotterdam], the UK [England], and Spain [Zaragoza]) have compared dementia occurrence using consistent research methods between two timepoints in well-defined geographical areas. Findings from four of the five studies showed non-significant changes in overall dementia occurrence. The only significant reduction in overall prevalence was found in the study done in the UK, powered and designed explicitly from its outset to detect change across generations (decrease in prevalence of 22%; p=0.003). Findings from the study done in Zaragoza (Spain) showed a significant reduction in dementia prevalence in men (43%; p=0.0002). The studies estimating incidence done in Stockholm and Rotterdam reported non-significant reductions. Such reductions could be the outcomes from earlier population-level investments such as improved education and living conditions, and better prevention and treatment of vascular and chronic conditions. This evidence suggests that attention to optimum health early in life might benefit cognitive health late in life. Policy planning and future research should be balanced across primary (policies reducing risk and increasing cognitive reserve), secondary (early detection and screening), and tertiary (once dementia is present) prevention. Each has their place, but upstream primary prevention has the largest effect on reduction of later dementia occurrence and disability.

The worldwide costs of dementia 2015 and comparisons with 2010.

In 2010, Alzheimers Disease International presented estimates of the global cost of illness (COI) of dementia. Since then, new studies have been conducted, and the number of people with dementia has increased. Here, we present an update of the global cost estimates.

Inflammation and frailty in the elderly: A systematic review and meta-analysis

The pathogenesis of frailty and the role of inflammation is poorly understood. We examined the evidence considering the relationship between inflammation and frailty through a systematic review and meta-analysis. A systematic literature search of papers providing data on inflammatory biomarkers and frailty was carried out in major electronic databases from inception until May 2016. From 1856 initial hits, 35 studies (32 cross-sectional studies n=3232 frail, n=11,483 pre-frail and n=8522 robust, and 563 pre-frail+robust; 3 longitudinal studies n=3402 participants without frailty at baseline) were meta-analyzed. Cross-sectional studies reported that compared to 6757 robust participants, both 1698 frail (SMD=1.00, 95%CI: 0.40-1.61) and 8568 pre-frail (SMD=0.33, 95%CI: 0.04-0.62) participants had significantly higher levels of C-reactive protein (CRP). Frailty (n=1057; SMD=1.12, 95%CI: 0.27-2.13) and pre-frailty (n=4467; SMD=0.56, 95%CI: 0.00-1.11) were associated with higher serum levels of interleukin-6 compared to people who were robust (n=2392). Frailty and pre-frailty were also significantly associated with elevated white blood cell and fibrinogen levels. In three longitudinal studies, higher serum CRP (OR=1.06, 95%CI: 0.78-1.44,) and IL-6 (OR=1.19, 95%CI: 0.87-1.62) were not associated with frailty. In conclusion, frailty and pre-frailty are associated with higher inflammatory parameters and in particular CRP and IL-6. Further longitudinal studies are needed.

ReviewInflammation and frailty in the elderly: A systematic review and meta-analysis

The pathogenesis of frailty and the role of inflammation is poorly understood. We examined the evidence considering the relationship between inflammation and frailty through a systematic review and meta-analysis. A systematic literature search of papers providing data on inflammatory biomarkers and frailty was carried out in major electronic databases from inception until May 2016. From 1856 initial hits, 35 studies (32 cross-sectional studies n=3232 frail, n=11,483 pre-frail and n=8522 robust, and 563 pre-frail+robust; 3 longitudinal studies n=3402 participants without frailty at baseline) were meta-analyzed. Cross-sectional studies reported that compared to 6757 robust participants, both 1698 frail (SMD=1.00, 95%CI: 0.40-1.61) and 8568 pre-frail (SMD=0.33, 95%CI: 0.04-0.62) participants had significantly higher levels of C-reactive protein (CRP). Frailty (n=1057; SMD=1.12, 95%CI: 0.27-2.13) and pre-frailty (n=4467; SMD=0.56, 95%CI: 0.00-1.11) were associated with higher serum levels of interleukin-6 compared to people who were robust (n=2392). Frailty and pre-frailty were also significantly associated with elevated white blood cell and fibrinogen levels. In three longitudinal studies, higher serum CRP (OR=1.06, 95%CI: 0.78-1.44,) and IL-6 (OR=1.19, 95%CI: 0.87-1.62) were not associated with frailty. In conclusion, frailty and pre-frailty are associated with higher inflammatory parameters and in particular CRP and IL-6. Further longitudinal studies are needed.

Recent global trends in the prevalence and incidence of dementia, and survival with dementia

BackgroundCurrent projections of the scale of the coming dementia epidemic assume that the age- and sex-specific prevalence of dementia will not vary over time, and that population ageing alone (increasing the number of older people at risk) drives the projected increases. The basis for this assumption is doubtful, and secular trends (that is, gradual decreases or increases in prevalence over long-term periods) are perfectly plausible.MethodsWe carried out a systematic review of studies of trends in prevalence, incidence and mortality for people with dementia, conducted since 1980.ResultsWe identified nine studies that had tracked dementia prevalence, eight that had tracked dementia incidence, and four that had tracked mortality among people with dementia. There was some moderately consistent evidence to suggest that the incidence of dementia may be declining in high-income countries. Evidence on trends in the prevalence of dementia were inconsistent across studies and did not suggest any clear overall effect. Declining incidence may be balanced by longer survival with dementia, although mortality trends have been little studied. There is some evidence to suggest increasing prevalence in East Asia, consistent with worsening cardiovascular risk factor profiles, although secular changes in diagnostic criteria may also have contributed.ConclusionsWe found no evidence to suggest that the current assumption of constant age-specific prevalence of dementia over time is ill-founded. However, there remains some uncertainty as to the future scale of the dementia epidemic. Population ageing seems destined to play the greatest role, and prudent policymakers should plan future service provision based upon current prevalence projections. Additional priorities should include investing in brain health promotion and dementia prevention programs, and monitoring the future course of the epidemic to chart the effectiveness of these measures.

Prevalence studies of dementia in mainland china, Hong Kong and taiwan: a systematic review and meta-analysis.

Background Many studies have considered the prevalence of dementia in mainland China, Hong Kong and Taiwan. However, area level estimates have not been produced. This study examines area differences across mainland China, Hong Kong and Taiwan adjusting for the effect of methodological factors with the aim of producing estimates of the numbers of people with dementia in these areas. Method and Findings A search of Chinese and English databases identified 76 dementia prevalence studies based on samples drawn from mainland China, Hong Kong and Taiwan between 1980 and 2012. A pattern of significantly decreasing prevalence was observed from northern, central, southern areas of mainland China, Hong Kong and Taiwan. Area variations in dementia prevalence were not explained by differences in methodological factors (diagnostic criteria, age range, study sample size and sampling method), socioeconomic level or life expectancy between areas. The results of meta-analysis were applied to current population data to provide best estimate. Based on the DSM-IV diagnostic criteria, the total number of people aged 60 and over with dementia in mainland China, Hong Kong and Taiwan is 8.4 million (4.6%, 95% CI: 3.4, 5.8) and in northern, central and southern areas are 3.8 (5.1%, 95% CI: 4.1, 6.1), 3.2 (4.4%, 95% CI: 3.2, 5.6) and 1.2 (3.9%, 95% CI: 2.3, 5.4) million respectively. These estimates were mainly based on the studies existing in highly developed areas and potentially affected by incomplete and insufficient data. Conclusions The findings of this review provide a robust estimate of area differences in dementia prevalence. Application of the estimated prevalence to population data reveals the number of people with dementia is expected to double every 20 years, areas in mainland China will be facing the greatest dementia challenge.

The changing prevalence and incidence of dementia over time — current evidence

Dementia is an increasing focus for policymakers, civil organizations and multidisciplinary researchers. The most recent descriptive epidemiological research into dementia is enabling investigation into how the prevalence and incidence are changing over time. To establish clear trends, such comparisons need to be founded on population-based studies that use similar diagnostic and research methods consistently over time. This narrative Review synthesizes the findings from 14 studies that investigated trends in dementia prevalence (nine studies) and incidence (five studies) from Sweden, Spain, the UK, the Netherlands, France, the USA, Japan and Nigeria. Besides the Japanese study, these studies indicate stable or declining prevalence and incidence of dementia, and some provide evidence of sex-specific changes. No single risk or protective factor has been identified that fully explains the observed trends, but major societal changes and improvements in living conditions, education and healthcare might have favourably influenced physical, mental and cognitive health throughout an individuals life course, and could be responsible for a reduced risk of dementia in later life. Analytical epidemiological approaches combined with translational neuroscientific research could provide a unique opportunity to explore the neuropathology that underlies changing occurrence of dementia in the general population.

The association between community environment and cognitive function: a systematic review

PurposesThe aim of this study is to review the published evidence on the association between community environment and cognitive function in older people, focusing on the findings and a critique of the existing studies.MethodsA literature search was conducted to identify studies linking the community environment and cognitive function in older people. The results and methodological factors, including the definition of community, individual level characteristics and the measurements of cognitive function and community environment were extracted from each study. The measurements of community environment were mainly categorized into two types: compositional, generated by aggregating individual and household data (community-level socioeconomic status, deprivation index) and contextual, targeting at the features of built or social environment in local areas (green space, street conditions, crime rate).ResultsFourteen of the fifteen studies used compositional measurements such as community-level socioeconomic status and deprivation index and significant associations were found in eleven studies. Some individual level factors (ethnicity, genotype and socioeconomic status) were found to modify the association between community environment and cognitive function. Few contextual measurements were included in the existing studies. A conceptual framework for the pathway from community environment to cognitive function of older people is provided in this review.ConclusionsTo disentangle the additional effect of place from individual risk factors and investigate the casual direction of community environment and cognition in later life, longitudinal studies with measurements targeting built and social environments of community and change of cognitive functions over time need to be included in future studies.

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

There 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.

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

This study aims to synthesise evidence on time trends of dementia prevalence in East Asian countries including Japan, China, South Korea and Taiwan and assess the impact of the societal changes on future prevalence.