Prevalence of dementia in a southern European population in two different time periods: the ZARADEMP Project

Changes in the prevalence of dementia in Australia and its association with geographic remoteness

BACKGROUND

The exact prevalence of dementia in Australia is ambiguous. Australia is a vast continent with a small population, and 80% of the population live in five cities. This study explores recent changes in the prevalence of dementia. It also investigates geographic remoteness as a potential risk factor for developing dementia.

METHODS

Survey of Disability, Ageing and Carers (SDAC), a nationally representative database, was used to conduct this study. A total of 74,862 and 65,487 individuals from 2015 and 2018, respectively, were considered for this study. A multivariable logistic regression model was used to evaluate the association between dementia and geographic remoteness for older adults aged 65 years and over.

RESULTS

The results reveal that from 2015 to 2018, the prevalence of dementia among adults aged 65 years and older was higher in 2018 (5,229 per 100,000) than in 2015 (5,099 per 100,000). Significant geographical differences in the prevalence of dementia are observed among Australian adults, and this trend appears to be increasing. Furthermore, the unadjusted model revealed that, in 2015, older adults living in major cities had 1.29 (AOR: 1.29, 95% CI: 1.17-1.41) times higher odds of having dementia compared with their counterparts from outer regional and remote areas. In 2018, the adjusted model found that older adults living in major cities had 1.12 (AOR: 1.12, 95% CI: 1.01-1.25) times elevated odds of having dementia than their peers living in outer regional and remote areas.

CONCLUSION

There is a rising prevalence of dementia in Australia. Further investigation is required to identify the causes of this increase. Increased public health initiatives should concentrate on behavioural characteristics and contextual environmental factors to ameliorate this trend.

Prevalence of Dementia in Korea Based on Hospital Utilization Data from 2008 to 2016

PURPOSE

Dementia is an important health issue in Korea due to its associated medical costs. Our study aimed to estimate the prevalence of dementia in Korea by analyzing hospital utilization rates.

MATERIALS AND METHODS

We examined National Health Insurance data from 2008 to 2016 and identified all dementia cases. Crude and ageand sex-standardized prevalence were calculated. A generalized linear mixed model was used to estimate prevalence ratios.

RESULTS

We identified 176746 and 530269 dementia cases in 2008 and 2016, respectively. Alzheimer's disease was the most common dementia subtype (65.4% and 86.1% in 2008 and 2016, respectively). Across all age groups, the prevalence of dementia increased consistently: the increase was prominent among patients ≥85 years of age. Among patients ≥65 years of age, crude prevalence was estimated at 31.3 and 72.2 per 1000 population in 2008 and 2016, respectively. Age- and sex-standardized prevalence increased from 31.3 to 62.0 per 1000 population between 2008 and 2016, respectively. The prevalence ratio for dementia in 2016 was 2.02 times (95% confidence interval, 2.01-2.03) higher than that in 2008. When adjusted for age, dementia was more prevalent among females. The most common comorbidity was hypertension, followed by diabetes and stroke.

CONCLUSION

Our results demonstrated that hospital utilization for dementia increased significantly from 2008 to 2016, reflecting a proportional increase in the prevalence of dementia. Korean healthcare policy must prioritize dementia treatment.

Secular Trends in the Incidence of and Mortality Due to Alzheimer's Disease and Other Forms of Dementia in China From 1990 to 2019: An Age-Period-Cohort Study and Joinpoint Analysis

Background

The number of individuals with dementia is increasing, which negatively affects families, communities, and health care systems worldwide. The changes in the incidence of and mortality due to Alzheimer’s disease and other forms of dementia at the national level in China have remained unknown over the past three decades.

Methods

Following the general analytical strategy used in the Global Burden of Disease Study (GBD) 2019, the age- and sex-specific incidence and mortality rates for dementia in China were analyzed. Trends in the incidence of and mortality due to dementia from 1990 to 2019 were assessed by joinpoint regression analysis. The effects of age, period and cohort on the incidence of and mortality due to dementia were estimated by an age-period-cohort model.

Results

The age-standardized incidence and mortality rates per 100,000 population were 103.83 (95% UI, 87.93–118.87) and 23.32 (95% UI, 5.66–61.31), respectively, for dementia in 2019. From 1990 to 2019, a significant average annual percentage change (AAPC) in the age-standardized incidence rate was observed in both males [0.49% (95% CI, 0.43–0.55%)] and females [0.31% (95% CI, 0.24–0.38%)], and the age-standardized mortality rate significantly increased in males [0.42% (95% CI, 0.31–0.53%)]. The population aged 55–59 years had the highest AAPC in the incidence of dementia [0.87% (95% CI, 0.81–0.93%)]. The age effect showed that the relative risks (RRs) of incident dementia and dementia-associated mortality increased with age among males and females, and individuals aged 60 years and older had significantly higher RRs. The RR of incident dementia increased with time, and the RR started to substantially increase in 2009. The cohort effect showed that the incidence decreased in successive birth cohorts.

Conclusion

Alzheimer’s disease and other forms of dementia continue to become more common among males and females in China, and the associated mortality rate in males significantly increased from 1990 to 2019. Early interventions should be implemented to reduce the burden of dementia on individuals at high risk in China.

A 9-Year Comparison of Dementia Prevalence in Korea: Results of NaSDEK 2008 and 2017

BACKGROUND

In many high-income Western countries, the prevalence of dementia had been reduced over the past decades.

OBJECTIVE

We investigated whether the prevalence of all-cause dementia, Alzheimer's disease, vascular dementia, and mild cognitive impairment (MCI) had changed in Korea from 2008 to 2017.

METHODS

Nationwide Survey on Dementia Epidemiology of Korea (NaSDEK) in 2008 and 2017 was conducted on representative elderly populations that were randomly sampled across South Korea. Both surveys employed a two-stage design (screening and diagnostic phases) and diagnosed dementia and MCI according to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders and the consensus criteria from the International Working Group, respectively. The numbers of participants aged 65 years or older in the screening and diagnostic phases were 6,141 and 1,673 in the NaSDEK 2008 and 2,972 and 474 in the NaSDEK 2017, respectively.

RESULTS

The age- and sex-standardized prevalence of all-cause dementia and Alzheimer's disease showed nonsignificant decrease (12.3% to 9.8%, odds ratio [OR] = 0.89, 95% confidence interval [CI] = 0.54-1.48 for all-cause dementia; 7.6% to 6.8%, OR [95% CI] = 0.91 [0.58-1.42] for Alzheimer's disease). Vascular dementia decreased in the young-old population aged less than 75 years (2.7% to 0.001%, OR [95% CI] = 0.04 [0.01-0.15]) and in women (1.9% to 0.5%, OR [95% CI] = 0.27 [0.10-0.72]) while MCI remained stable (25.3% to 26.2%, OR [95% CI] = 1.08 [0.67-1.73]).

CONCLUSION

We found that the prevalence of dementia in Korea showed a nonsignificant decrease between 2008 and 2017.

Population estimate of people with clinical Alzheimer's disease and mild cognitive impairment in the United States (2020-2060)

INTRODUCTION

The estimate of people with clinical Alzheimer's disease (AD) and mild cognitive impairment provides an understanding of the disease burden.

METHODS

We estimated people with cognitive impairment using a quasibinomial regression model in 10,342 participants with cognitive test scores.

RESULTS

The 2020 US Census-adjusted prevalence of clinical AD was 11.3% (95% confidence interval [CI] = 10.7-11.9): 10.0% among non-Hispanic Whites, 14.0% among Hispanics, and 18.6% among non-Hispanic Blacks. We estimate that in 2020, 6.07 (95% CI = 5.75-6.38) million people were living with clinical AD, which increases to 13.85 (95% CI = 12.98-14.74) million in 2060, 423% higher among Hispanics, 192% higher among Blacks, and 63% higher among Whites. However, there are predicted to be more significant increases in later years among those over 85 and women compared to men.

DISCUSSION

The number of people with clinical AD will increase as the "baby boom" generation reaches older ages, exerting a strong upward influence on disease burden.

Trends in the prevalence of cognitive impairment in Chinese older adults: based on the Chinese Longitudinal Healthy Longevity Survey cohorts from 1998 to 2014

In the context of a rapidly ageing Chinese population, this study aims to examine trends in the prevalence of cognitive impairment among people ≥65 y of age in China. Our sample is 72 821 adults aged 65–105 y from the seven waves of the Chinese Longitudinal Healthy Longevity Survey, a national mixed longitudinal cohort. The Chinese version of the Mini-Mental State Examination was used to measure CI. Risk factor-adjusted prevalence trend was examined using multilevel regression models. Age-standardized prevalence of cognitive impairment increased from 11.00% in 1998 to 11.84% in 2008 and decreased to 8.88% in 2014. Older age, female gender, less education, rural residence, not married, lack of physical and cognitive activities, suffering from stroke, vision and hearing impairment, and activities of daily living disability were negatively associated with cognitive impairment. Our study suggests a decreasing trend of cognitive impairment prevalence in China. However, whether decreasing prevalence will contribute to a reduced burden of cognitive impairment given the ageing of the population is unknown.

Is milk and dairy intake a preventive factor for elderly cognition (dementia and Alzheimer's)? A quality review of cohort surveys

Milk and dairy (M&D) is a longstanding human food with widespread use. Many studies showed the preventive capacity of M&D in several human health disorders, but its utility in others is under discussion. Aging has been associated to elderly cognitive decline including dementia-Alzheimer syndrome (Dem-AD). The absence of a therapy to impede or postpone Dem-AD determines the need for its prevention, including nutritional factors. To evaluate the preventive capacity of M&D consumption in elderly Dem-AD we performed a systematic review in the main biomedical databases and information resources, but we present this study as a narrative review to discuss better the complexity of this subject. The elderly Dem-AD has a long pre-symptomatic period and the M&D intake has a widespread use. These determinants and the quality flaws of published studies impeach us to answer whether M&D consumption is preventive for Dem-AD. Moreover, two long Japanese cohorts suggest that M&D intake could prevent Dem-AD. Prospective cohorts beginning in midlife (or early life) could answer this question in the future.

Trend in the Incidence and Prevalence of Dementia in the Faroe Islands

Background:

Dementia has become an important public health, economic, and social issue. Knowledge about prevalence, incidence, and trends of dementia in a country is of crucial importance. However, no studies of incidence or prevalence of dementia have been undertaken in the Faroe Islands.

Objectives:

The aim was to estimate the overall and trend in incidence and prevalence of dementia among individuals ≥60 years in the Faroe Islands from 2010-2017.

Methods:

Population-based register study where all individuals ≥60 years with a dementia diagnosis from January 2010 to December 2017 were identified. The overall crude and age-and-sex-specific incidence and prevalence was assessed.

Results:

The overall crude incidence among individuals ≥60 years from 2010 to 2017 was 5.1 per 1000 individuals and the prevalence 22.5 per 1000 individuals. The age-and sex-standardized annual incidence of dementia fluctuated between 4.8 and 6.7 per 1000, with no clear secular trend while the age-and sex-standardized prevalence increased steadily from 14.5 in 2010 to 30.8 per 1000 individuals in 2017.

Conclusion:

The age-standardized incidence or prevalence estimates in the Faroes seem to be lower than in other countries. The incidence was relatively stable in the period while the prevalence of dementia simultaneously increased.

Gender and Educational Differences in the Association between Lifestyle and Cognitive Decline over 10 Years: The Doetinchem Cohort Study

BACKGROUND

Several modifiable risk factors for cognitive decline have been identified, but whether differences by gender and educational level exist is unclear.

OBJECTIVE

The present study aims to clarify this by prospectively investigating the relationship between health and lifestyle factors and cognitive functioning in different subgroups defined by gender and educational level.

METHODS

2,347 cognitive healthy individuals (mean age = 54.8, SD = 6.8, range: 41-71; 51.8% female; 26.2% low education) from the Doetinchem Cohort Study were examined for cognitive function at baseline, and at 5- and 10-year follow-up. Health- and lifestyle factors were captured by a poly-environmental risk score labelled 'LIfestyle for BRAin Health' (LIBRA). This score consists of 12 modifiable risk and protective factors for cognitive decline and dementia, with higher scores indicating greater risk (range: -2.7 to +12.7). Heterogeneity in associations between LIBRA and decline in verbal memory, cognitive flexibility, and mental speed between males and females and individuals with different levels of education were assessed in linear mixed models.

RESULTS

Overall, higher LIBRA scores predicted faster decline in verbal memory, cognitive flexibility, and mental speed over 10 years. Higher LIBRA scores were further associated with increased risk for incident cognitive impairment (one-point increase in LIBRA: HR = 1.09, 1.04-1.14, p = 0.001). In general, these effects were similar across gender and educational level.

CONCLUSION

A composite risk score comprising unhealthy lifestyle and relatively poor health in midlife is significantly associated with a worse course of cognition 10 years later. These associations were for the most part unrelated to gender or educational differences.

Trends in Prevalence of Dementia for People Accessing Aged Care Services in Australia

BACKGROUND

Studies in some high-income countries have reported a potential decline in the prevalence of dementia. Improvements in cardiovascular health may be contributing to this decline. The objective was to examine trends in prevalence of dementia and survival with dementia for people accessing aged care in Australia.

METHODS

A retrospective study of older people who accessed long-term care 2008-2014 (n = 348,311) and home care 2005-2014 (n = 188,846) in Australia was developed. The age- and sex-standardized prevalence for dementia by year of access to aged care was determined using direct standardization. Generalized linear models were used to determine change in the prevalence of dementia over time and change in 1-year mortality for people who accessed long-term care.

RESULTS

The age- and sex-standardized prevalence (95% confidence interval) of dementia declined from 50.0% (49.6, 50.5) in 2008 to 46.6% (46.0, 47.2) in 2014 for people accessing long-term care (absolute change 2008-2014: -3.8 [-4.6, -3.1]) and for people accessing home care from 25.9% (25.0, 26.5) in 2005 to 20.9% (20.2, 21.7) in 2014 (absolute change 2005-2014: -5.2 [-6.2, -4.1]). This decline in dementia occurred in concurrence with a decline in cerebrovascular disease in long-term care but despite the prevalence of hypertension, diabetes, high cholesterol, malnutrition, obesity, depression, and head injury increasing. For people accessing long-term care, 1-year mortality remained stable over time.

CONCLUSIONS

The decline in prevalence of dementia for people accessing aged care services in Australia is critical to future projection estimates and for planning of services. Further research to determine contributing factors to the decline is needed.

Prevalence and incidence of dementia in an older Chinese population over two decades: The role of education

INTRODUCTION

Secular trends of dementia prevalence and incidence have rarely been studied in the Chinese population.

METHODS

We examined the changes in dementia prevalence and incidence by comparing data from Shanghai Epidemiological Survey of Dementia and Alzheimer's disease (SESD) and Shanghai Aging Study (SAS) conducted two decades apart.

FINDINGS

The dementia prevalence and incidence in total participants in SAS were higher than that in SESD (prevalence: 6.44% vs 2.30%, P < .001; annual incidence: 2.58% vs 1.33%, P < .001). In participants with ≤6 years of education, the dementia prevalence in SAS was higher than that in SESD (6.39% vs 3.07%, P < .001); the annual dementia incidence in SAS was double that in SESD (3.63% vs 1.80%, P = .019).

DISCUSSION

We observed an increasing trend of dementia prevalence and incidence in the Chinese elderly, especially those with low education. The dramatic rise in numbers of people with dementia may happen most likely in low-educated populations.

Generating national projections of dementia cases for Ireland using a calibrated macro-simulation model

INTRODUCTION

Epidemiological data on dementia is not available in many European countries and regions due to the high cost and complexity of conducting large scale dementia screening studies. The available epidemiological studies identify potentially substantial variation in the prevalence of dementia over time and across Europe.

METHODS

In this paper we generate simulations of the number of dementia cases in Ireland from 1991 to 2036 using a three-state Markov illness-death model. Parameters values are selected for each simulation from a range using a random parameter search pattern. We employ a novel calibration method which exploits the strong relationship between dementia, ageing and mortality. Simulation weights are generated based on differences between observed and modelled cohorts of older people and the reported number of deaths from dementia. Irish Census data from 1991 to 2016 and the number of recorded deaths due to dementia in 2018 are used as calibration points. A weighted average projection of the number of dementia cases is generated.

RESULTS

We estimate a weighted average number of cases of dementia in 2016 of 54 877 increasing to 98 946 in 2036; this estimate is substantially lower than the estimates generated using extrapolation methods. We show the wide range of possible outcomes given the range in the available parameter estimates and show that irrespective of whether the incidence rate of dementia is declining the number of cases of dementia is rapidly increasing due to population ageing.

CONCLUSION

Previous studies have used parameter estimates from meta-analyses of the literature or from individual studies. In this paper we supplement these with a calibration approach using observed cause of death and population age structure data. These additional sources of data can be used to generate estimates of dementia prevalence in any country or region which has census data and data on deaths due to dementia.

A New Look at Cohort Trend and Underlying Mechanisms in Cognitive Functioning

OBJECTIVES

The prevalence of dementia in the United States seems to have declined over the last few decades. We investigate trends and their underlying mechanisms in cognitive functioning (CF) across 7 decades of birth cohorts from the Greatest Generation to Baby Boomers.

METHODS

Data come from 30,191 participants of the 1996-2014 Health and Retirement Study. CF is measured as a summary score on a 35-point cognitive battery of items. We use generalized linear models to examine the trends in CF and explanatory variables across birth cohorts. Then, Karlson-Holm-Breen decomposition method is used to evaluate the contribution of each explanatory variable to the trend of CF.

RESULTS

CF has been improving from the Greatest Generation to Late Children of Depression and War Babies, but then significantly declines since the Early-Baby Boomers and continues into Mid-Baby Boomers. This pattern is observed universally across genders, race/ethnicities, education groups, occupations, income, and wealth quartiles. The worsening CF among Baby Boomers does not originate from childhood conditions, adult education, or occupation. It can be attributed to lower household wealth, lower likelihood of marriage, higher levels of loneliness, depression and psychiatric problems, and more cardiovascular risk factors (e.g., obesity, physical inactivity, hypertension, stroke, diabetes, and heart disease).

DISCUSSION

The worsening CF among Baby Boomers may potentially reverse past favorable trends in dementia as they reach older ages and cognitive impairment becomes more common if no effective interventions and policy responses are in place.

Does Anxiety Increase the Risk of All-Cause Dementia? An Updated Meta-Analysis of Prospective Cohort Studies

Background: Anxiety has been suggested as a potentially modifiable risk factor for dementia, but results are still controversial. Our main objectives are to develop an updated meta-analysis of prospective population-based studies on the relationship between anxiety and risk of dementia, and to estimate the population fraction of dementia attributable to anxiety (PAF). Methods: We searched for cohort studies listed on PubMed or Web of Science from January 2018 to January 2020 that reported risk estimates for the association between anxiety and incident dementia. These were added to cohort studies published before January 2018 that were used in a previously published meta-analysis. Fully adjusted RRs were pooled using random effects models. We estimated the proportion of incident dementia attributable to anxiety by using PAF. Results: The meta-analysis included nine prospective cohorts from eight studies, representing 29,608 participants. The overall relative risk (RR) of dementia was 1.24 (95% CI: 1.06–1.46) and the PAF of dementia due to anxiety was 3.9%. Conclusions: Anxiety is significantly associated with an increased risk of all-cause dementia. The treatment or prevention of anxiety might help to reduce dementia incidence rates, but more research is needed to clarify whether anxiety is a cause of dementia rather than a prodrome.

Is Alzheimer's Disease Risk Modifiable?

Population-based clinic-pathological studies have established that the most common pathological substrate of dementia in community-dwelling elderly people is mixed, especially Alzheimer's disease (AD) and cerebrovascular ischemic disease (CVID), rather than pure AD. While these could be just two frequent unrelated comorbidities in the elderly, epidemiological research has reinforced the idea that mid-life (age <65 years) vascular risk factors increase the risk of late-onset (age ≥ 65 years) dementia, and specifically AD. By contrast, healthy lifestyle choices such as leisure activities, physical exercise, and Mediterranean diet are considered protective against AD. Remarkably, several large population-based longitudinal epidemiological studies have recently indicated that the incidence and prevalence of dementia might be decreasing in Western countries. Although it remains unclear whether these positive trends are attributable to neuropathologically definite AD versus CVID, based on these epidemiological data it has been estimated that a sizable proportion of AD cases could be preventable. In this review, we discuss the current evidence about modifiable risk factors for AD derived from epidemiological, preclinical, and interventional studies, and analyze the opportunities for therapeutic and preventative interventions.

Is it time to use real-world data from primary care in Alzheimer's disease?

BACKGROUND

The analysis of real-world data in clinical research is rising, but its use to study dementia subtypes has been hardly addressed. We hypothesized that real-world data might be a powerful tool to update AD epidemiology at a lower cost than face-to-face studies, to estimate the prevalence and incidence rates of AD in Catalonia (Southern Europe), and to assess the adequacy of real-world data routinely collected in primary care settings for epidemiological research on AD.

METHODS

We obtained data from the System for the Development of Research in Primary Care (SIDIAP) database, which contains anonymized information of > 80% of the Catalan population. We estimated crude and standardized incidence rates and prevalences (95% confidence intervals (CI)) of AD in people aged at least 65 years living in Catalonia in 2016.

RESULTS

Age- and sex-standardized prevalence and incidence rate of AD were 3.1% (95%CI 2.7-3.6) and 4.2 per 1000 person-years (95%CI 3.8-4.6), respectively. Prevalence and incidence were higher in women and in the oldest people.

CONCLUSIONS

Our incidence and prevalence estimations were slightly lower than the recent face-to-face studies conducted in Spain and higher than other analyses of electronic health data from other European populations. Real-world data routinely collected in primary care settings could be a powerful tool to study the epidemiology of AD.

Temporal changes in the likelihood of dementia and MCI over 18 years in a population sample

OBJECTIVE

To examine the temporal changes in the likelihood of dementia and mild cognitive impairment (MCI) between 1993 and 2012 using a short battery of cognitive tests.

METHODS

A cohort of 10,342 participants underwent a short battery of cognitive tests collected during triennial in-home interviews with 2,794 of those evaluated for the clinical diagnosis of dementia and MCI. We used a generalized logit regression model to estimate the likelihood of dementia and MCI, and a quasibinomial regression model to examine the temporal changes in those likelihood scores.

RESULTS

A short battery of cognitive tests-delayed story recall test, Symbol Digit Modalities Test, and the Mini-Mental State Examination-were associated with the clinical diagnosis of dementia and MCI. The classification accuracy of likelihood scores was 0.92 for dementia and 0.85 for MCI. After adjusting for age, race/ethnicity, and education, the likelihood of dementia in the population decreased from 21.6% (95% confidence interval [CI] 20.9%-22.3%) to 18.9% (95% CI 18.1%-19.7%) between 1993-1996 and 2000-2002 and showed no significant decline between 2000-2002 and 2009-2012 (-0.2%, 95% CI -1.1% to 0.7%). The estimated likelihood of MCI remained similar between 1993-1996 and 2009-2012 (29.0%, 95% CI 27.9%-30.1%), but showed a nonsignificant decrease in 2000-2002.

CONCLUSION

The likelihood scores based on a short battery of cognitive tests can serve as a measure of dementia and MCI in epidemiologic studies. The decline in the likelihood of dementia and MCI over earlier years was not sustained in later years.

Secular Trends in Dementia Prevalence and Incidence Worldwide: A Systematic Review

BACKGROUND

Time trends for dementia prevalence and incidence rates have been reported over the past seven decades in different countries and some have reported a decline.

OBJECTIVE

To undertake a systematic review to critically appraise and provide an evidence-based summary of the magnitude and direction of the global changes in dementia prevalence and incidence across time.

METHODS

Medline, EMBASE, and PsychINFO were searched for studies focused on secular trends in dementia prevalence and/or incidence until 18 December 2017. In total, 10,992 articles were identified and 43 retained.

RESULTS

Overall, prevalence rates are largely increasing (evidence primarily from record-based surveys and cohort studies in Japan, Canada, and France) or have remained stable (evidence primarily from cohort studies in Sweden, Spain and China). A significant decline in prevalence has however been reported in more recent studies (i.e., from 2010 onwards) from Europe (e.g., UK and Sweden) and the USA. Incidence rates have generally remained stable or decreased in China, Canada, France, Germany, Denmark, Sweden, the Netherlands, UK, and USA. An increase has only been reported in five countries: Italy, Japan, Wales, Germany, and the Netherlands. Only one study reported findings (stability in incidence) from a low and middle-income country using data from Nigeria.

CONCLUSIONS

The evidence on secular trends in the prevalence and incidence of dementia is mixed including contradictory findings using different (and in some cases the same) datasets in some countries (e.g., the USA, UK, and Sweden). This making it difficult to draw concrete conclusions. However, declining trends recently observed in some high-income Western countries in the most recent two decades including the UK, USA, and Sweden are encouraging. Updated dementia prevalence and incidence estimates will inform public health and financial planning as well as development of prevention strategies.

Time Trend in Persistent Cognitive Decline: Results From the Longitudinal Aging Study Amsterdam

Objective

To study time trends in the incidence of persistent cognitive decline (PCD), and whether an increase or decrease is explained by changes in well-known risk factors of dementia.

Method

Data from the Longitudinal Aging Study Amsterdam over a period of 20 years were used. Subsamples of 65-88 year-olds were selected at 7 waves, with numbers ranging from 1,800 to 1,165. Within-person change in cognitive functioning was used to determine PCD. In logistic generalized estimating equations (GEE), time (0, 3, 6, 9, 13, and 16 years) was the main predictor of 3-year PCD incidence. Explanatory variables were lagged one wave before incident PCD and included in separate models.

Results

PCD incidence was 2.5% at first, and 3.4% at last follow-up. GEE showed a positive time trend for PCD incidence [Exp(B)time = 1.042; p < .001]. None of the explanatory variables significantly changed the strength of the regression coefficient of linear time. Higher age, lower education, diabetes mellitus, smoking, lower body-mass index, and lower level of physical activity were associated with higher incidence of PCD.

Conclusion

An increase in PCD incidence over time was found. Although well-known risk factors were associated with incidence per se, they did not explain the increase in incidence of PCD.

Aging without Dementia is Achievable: Current Evidence from Epidemiological Research

Both the incidence and the prevalence of dementia increase exponentially with increasing age. This raises the question of whether dementia is an inevitable consequence of aging or whether aging without dementia is achievable. In this review article, we sought to summarize the current evidence from epidemiological and neuropathological studies that investigated this topic. Epidemiological studies have shown that dementia could be avoided even at extreme old ages (e.g., centenarians or supercentenarians). Furthermore, clinico-neuropathological studies found that nearly half of centenarians with dementia did not have sufficient brain pathology to explain their cognitive symptoms, while intermediate-to-high Alzheimer pathology was present in around one-third of very old people without dementia or cognitive impairment. This suggests that certain compensatory mechanisms (e.g., cognitive reserve or resilience) may play a role in helping people in extreme old ages escape dementia syndrome. Finally, evidence has been accumulating in recent years indicating that the incidence of dementia has declined in Europe and North America, which supports the view that the risk of dementia in late life is modifiable. Evidence has emerged that intervention strategies that promote general health, maintain vascular health, and increase cognitive reserve are likely to help preserve cognitive function till late life, thus achieving the goal of aging without dementia.

Epidemiology of dementia: prevalence and incidence estimates using validated electronic health records from primary care

Purpose

Updated estimates of incidence and prevalence of dementia are crucial to ensure adequate public health policy. However, most of the epidemiological studies in the population in Spain were conducted before 2010. This study assessed the validity of dementia diagnoses recorded in electronic health records contained in a large primary-care database to determine if they could be used for research purposes. Then, to update the epidemiology of dementia in Catalonia (Spain), we estimated crude and standardized prevalence and incidence rates of dementia in Catalonia in 2016.

Methods

The System for the Development of Research in Primary Care (SIDIAP) database contains anonymized information for >80% of the Catalan population. Validity of dementia codes in SIDIAP was assessed in patients at least 40 years old by asking general practitioners for additional evidence to support the diagnosis. Crude and standardized incidence and prevalence (95% CI) in people aged ≥65 years were estimated assuming a Poisson distribution.

Results

The positive predictive value of dementia diagnoses recorded in SIDIAP was estimated as 91.0% (95% CI 87.5%–94.5%). Age-and sex-standardized incidence and prevalence of dementia were 8.6/1,000 person-years (95% CI 8.0–9.3) and 5.1% (95% CI 4.5%–5.7%), respectively.

Conclusion

SIDIAP contains valid dementia records. We observed incidence and prevalence estimations similar to recent face-to-face studies conducted in Spain and higher than studies using electronic health data from other European populations.

Temporal Trends in the Level and Decline of Cognition and Disability in an Elderly Population: The PAQUID Study

In line with declining trends in dementia incidence, we compared the cognitive and functional evolution of 2 "generations" of elderly individuals aged 78-88 years, who were included 10 years apart in the French Personnes Agées Quid cohort (n = 612 in 1991-1992 and n = 628 in 2001-2002) and followed-up for 12 years with assessments of cognition and disability. The impact of specific risk factors on this evolution was evaluated. Differences between the generations in baseline levels and decline over time were estimated using a joint model to account for differential attrition. Compared with the first generation, the second generation had higher performances at baseline on 4 cognitive tests (from P < 0.005). Differences in global cognition, verbal fluency, and processing speed, but not in working memory, were mostly explained by improvement in educational level. The second generation also exhibited less cognitive decline in verbal fluency and working memory. Progression of disability was less over the follow-up period for the second generation than for the first. The cognitive state of this elderly population improved, partially due to improvements in educational level.

Prevalence and incidence of clinically diagnosed Alzheimer's disease dementia from 1994 to 2012 in a population study

INTRODUCTION

The trends in prevalence and incidence of Alzheimer's disease (AD) dementia remain uncertain.

METHODS

A sample of 2794 participants with a clinical diagnosis for AD dementia were included.

RESULTS

The 2010 census standardized prevalence of AD dementia was 14.5% (95% CI = 13.7-15.3), and annual incidence was 2.3% (1.7-2.9). Both prevalence and incidence showed substantial variation over time, but no secular trends. The prevalence of AD dementia did not change significantly from 14.6% (95% CI = 13.0, 16.2) in 1994-1997 to 14.7% (95% CI = 13.2, 16.2) in 2010-2012 (P = .84). The annual incidence of AD dementia was 2.8% (95% CI = 2.2, 3.2) in 1998-2000 and 2.2% (95% CI = 1.6, 2.8) in 2004-2006 (P = .20) and remained steady in 2010-2012. The prevalence and incidence among African Americans were approximately twice than those among European Americans.

CONCLUSIONS

The prevalence and incidence of AD dementia showed substantial variation between 1994 and 2012, but no secular trend.

Evolution of dementia diagnosis over time (1988-2013): Evidence from French and English cohorts. Implication for secular trends analyses

INTRODUCTION

The aims of this study are to examine the evolution of clinical dementia diagnosis over 3 decades and to investigate secular trends of dementia.

METHODS

Four cohorts covering a period from 1988 to 2013 were used: the Personnes Agées Quid and Three-City-Bordeaux studies, and the Cognitive Function and Aging Study (CFAS) I and II. Mini-Mental State Examination scores at clinical diagnosis were evaluated over a 24-year follow-up period in French studies. An algorithmic approach was applied to CFAS I and II to provide dementia prevalence and incidence estimates.

RESULTS

A significant increase of the Mini-Mental State Examination score at diagnosis was observed until 2000 and a significant decrease after. We reported a prevalence of 8.8% for CFAS I (1990-1993) compared with a prevalence of 6.5% in CFAS II (2008-2011). The 2-year incidence rate was estimated at 31.2/1000 (95% confidence interval = 28.0-34.8) for CFAS I and 15.0/1000 (95% confidence interval = 13.5-16.7) for CFAS II.

DISCUSSION

Applying a stable algorithm to different cohorts across time can provide a robust method for time trends estimation.

Secular Trends in the Incidence of Dementia in a Multi-Ethnic Community

BACKGROUND

Determination of secular trends in cognitive aging is important for prioritization of resources, services, and research in aging populations. Prior studies have identified declining dementia incidence associated with changes in cardiovascular risk factors and increased educational attainment. However, few studies have examined these factors in multi-ethnic cohorts.

OBJECTIVE

To identify secular trends in the incidence rate of dementia in an elderly population.

METHODS

Participants in this study were drawn from the Washington Heights-Inwood Columbia Aging Project, a multi-ethnic cohort study of northern Manhattan residents aged 65 years and older. Cox proportional hazards models were used to examine differences in the incidence of dementia in cohorts recruited in 1992 and 1999, with age at dementia or age at last follow-up visit as the "time-to-event" variable.

RESULTS

Overall, there was a 41% reduction in the hazard ratio for dementia among participants in the 1999 cohort compared with those in the 1992 cohort, adjusting for age, sex, race, and baseline memory complaints (HR = 0.59). The reduction in incidence was greatest among non-Hispanic Whites and African-Americans and lowest among Hispanic participants (HRs = 0.60, 0.52 and 0.64, respectively), and was associated with increases in level of educational attainment, especially among African-Americans. Reduction in incidence of dementia was also greater among persons 75 years or older than among younger participants (HR = 0.52 versus HR = 0.69).

CONCLUSIONS

Our results support previous findings that secular trends in dementia incidence are changing, including in aging minority populations.

Differences in Dementia Beliefs between Non-Demented Public Screeners and In-Home Screeners and Their Potential Impact on Future Dementia Screening Intention: The Nakajima Study

In many cohort studies of dementia, while differences in sociodemographic characters between responders and non-responders of dementia screening have been reported, differences in dementia beliefs have been relatively less known. The aims of this study were to clarify dementia beliefs and to explore potential impacts on an intention to attend a future dementia screening in public screeners and in-home screeners, respectively. We performed a cross-sectional population-based study using a question about an intention to attend a future dementia screening and a questionnaire on dementia beliefs. Subjects were all residents aged 65 years or older in the north area of Nakajima, Japan (n = 385). All subjects were asked to attend a public dementia screening first. An in-home dementia screening was subsequently conducted in subjects with non-responders to a public screening. The questionnaire consisted of four dementia beliefs: "perceived susceptibility," "perceived severity," "perceived barriers," and "perceived benefits." Public screeners significantly expressed an intention to attend a future dementia screening more than in-home screeners (p = 0.002). In in-home screeners, low "perceived severity" were significantly associated with an intention to attend a future dementia screening [adjusted OR (95% CI) = 0.51 (0.32-0.80)]. In both public and in-home screeners, high "perceived benefits" were significantly associated with an intention to attend a future dementia screening [adjusted OR (95% CI) = 2.13 (1.46-3.10); adjusted OR (95% CI) = 2.56 (1.22-5.35), respectively]. It is necessary to reduce "perceived severity" among in-home screeners to increase dementia screening participants.

Diagnosis of Dementia in the Specialist Setting: A Comparison Between the Swedish Dementia Registry (SveDem) and the Registry of Dementias of Girona (ReDeGi)

The aim of this study was to compare the frequency of dementia diagnoses from two dementia registries in Europe. Patients registered between 2007 and 2013 in the Swedish Dementia Registry (SveDem; Sweden) and in the Registry of Dementias of Girona (ReDeGi; North-East of Spain) were selected. We compared sociodemographic data, Mini-Mental State Examination (MMSE) scores, dementia subtype, and medication consumption of 22,384 cases from SveDem and 5,032 cases from ReDeGi. The average age (78.1 years SveDem versus 79.7 years ReDeGi) and the gender (female 58.2% SveDem versus 61.5% ReDeGi) did not greatly differ. MMSE score at diagnosis was higher for SveDem cases (22.1 versus 17.8). Alzheimer’s disease (AD) accounted for the main dementia subtype (36.6% SveDem versus 55.6% ReDeGi). The proportion of vascular dementia (VaD) and mixed dementia was higher in SveDem (18.8% versus 6.4% and 24.9 versus 13.4%), with an odds ratio (OR) and 95% confidence interval (CI) for SveDem relative to the ReDeGi of 3.41 (3.03–3.84) for VaD, and 2.15 (1.97–2.35) for mixed dementia. This was at the expense of a lower frequency of AD in SveDem (OR 0.41; 95% CI 0.39–0.44). Other dementia diagnoses such as frontotemporal dementia or dementia with Lewy bodies did not significantly differ between registries (2.3% versus 2.9%; 1.9 versus 3.1%). Large differences in medication consumption at the time of dementia diagnosis were detected (4.7 treatments SveDem versus 6.8 ReDeGi). Northern and southern European dementia cohorts differ in demographic characteristics, MMSE score at diagnosis, and drug treatment profile.

Report by the Spanish Foundation of the Brain on the social impact of Alzheimer disease and other types of dementia

INTRODUCTION

Knowledge of the socioeconomic impact of dementia-related disorders is essential for appropriate management of healthcare resources and for raising social awareness.

METHODS

We performed a literature review of the published evidence on the epidemiology, morbidity, mortality, associated disability and dependence, and economic impact of dementia and Alzheimer disease (AD) in Spain.

CONCLUSIONS

Most population studies of patients older than 65 report prevalence rates ranging from 4% to 9%. Prevalence of dementia and AD is higher in women for nearly every age group. AD is the most common cause of dementia (50%-70% of all cases). Dementia is associated with increased morbidity, mortality, disability, and dependence, and results in a considerable decrease in quality of life and survival. Around 80% of all patients with dementia are cared for by their families, which cover a mean of 87% of the total economic cost, resulting in considerable economic and health burden on caregivers and loss of quality of life. The economic impact of dementia is huge and difficult to evaluate due to the combination of direct and indirect costs. More comprehensive programmes should be developed and resources dedicated to research, prevention, early diagnosis, multidimensional treatment, and multidisciplinary management of these patients in order to reduce the health, social, and economic burden of dementia.

Time, Sex, Gender, History, and Dementia

A growing body of epidemiologic evidence indicates a decline in the incidence or prevalence of dementia in high income countries in the past 25 years. In this commentary, I first suggest that the decline in the incidence or prevalence of dementia is not explained completely by the factors considered so far, and that a broader historical perspective may be needed. Second, I suggest that the overall declining trend may conceal trends in opposite directions for the two major subtypes of dementia, the neurovascular and the neurodegenerative type. Third, I suggest some areas of future research to further elucidate the trends. The future of dementia remains somewhat unclear. Even if the incidence continues to decline, the prevalence may remain the same or increase if survival of persons affected by dementia increases. In addition, even if the prevalence declines, the total number of persons affected by dementia may remain the same or increase if the size of the elderly population expands. Finally, we cannot be sure that the decline in incidence will continue in the coming decades. With cautious optimism, we may conclude that the burden of dementia may be modified over time by human practices, including public health and medicine.

The prevalence of dementia in a Portuguese community sample: a 10/66 Dementia Research Group study

Background

Dementia imposes a high burden of disease worldwide. Recent epidemiological studies in European community samples are scarce. In Portugal, community prevalence data is very limited. The 10/66 Dementia Research Group (DRG) population-based research programmes are focused in low and middle income countries, where the assessments proved to be culture and education fair. We applied the 10/66 DRG prevalence survey methodology in Portugal, where levels of illiteracy in older populations are still high.

Methods

A cross-sectional comprehensive one-phase survey was conducted of all residents aged 65 and over of two geographically defined catchment areas in Southern Portugal (one urban and one rural site). Nursing home residents were not included in the present study. Standardized 10/66 DRG assessments include a cognitive module, an informant interview and the Geriatric Mental State-AGECAT, providing data on dementia diagnosis and subtypes, mental disorders including depression, physical health, anthropometry, demographics, disability/functioning, health service utilization, care arrangements and caregiver strain.

Results

We interviewed 1405 old age participants (mean age 74.9, SD = 6.7 years; 55.5% women) after 313 (18.2%) refusals to participate.

The prevalence rate for dementia in community-dwellers was 9.23% (95% CI 7.80–10.90) using the 10/66 DRG algorithm and 3.65% (95% CI 2.97–4.97) using DSM-IV criteria. Pure Alzheimer’s disease was the most prevalent dementia subtype (41.9%). The prevalence of dementia was strongly age-dependent for both criteria, but there was no association with sex.

Conclusions

Dementia prevalence was higher than previously reported in Portugal. The discrepancy between prevalence according to the 10/66 DRG algorithm and the DSM-IV criteria is consistent with that observed in less developed countries; this suggests potential underestimation using the latter approach, although relative validity of these two approaches remains to be confirmed in the European context. We improved the evidence base to raise awareness and empower advocacy about dementia in Portugal, so that the complex needs of frail older people may be met in better ways.

The time trends of cognitive impairment incidence among older Chinese people in the community: based on the CLHLS cohorts from 1998 to 2014

Objective

to examine a 16-year trend in cognitive impairment (CI) incidence and associated factors among older Chinese people.

Subjects

aged 60 and above whose cognitive function were normal at their first test.

Methods

a secondary analysis that identified subjects from the database of Chinese Longitudinal Healthy Longevity Survey (CLHLS). The database contained mixed longitudinal cohorts of older Chinese people surveyed in 1998, 2000, 2002, 2005, 2008-09, 2011-12 and 2014. The cognitive function of subjects was tested using the Chinese Mini-Mental State Examination (CMMSE) in each wave. The unique individual code identified a mixed cohort of 17,896 subjects who had multiple CMMSE measures over a 16-year period and available covariates for the analysis. CI was defined as the CMMSE score below 18 points. Crude and age-standardised incidence of CI by gender were calculated by year of survey. Risk factor adjusted time trends in the incidence were examined using multilevel regression models.

Results

age-standardised CI incidence decreased from 58.77‰ to 10.09‰ (P < 0.001) from 1998 to 2014, and this decrease remained after adjusting for covariates. About 15.8% in the observed decline was explained by higher education, and 7.9% was due to health practice (regular exercise, physical activity and cognitive activity), beyond age and gender effects.

Conclusion

the CI incidence among older Chinese people decreased from 1998 to 2014. Lower education level and less frequent health practices mentioned above were important risk factors in CI prevention.

Decreasing prevalence of dementia in 85-year olds examined 22 years apart: the influence of education and stroke

Individuals aged 80 years and older constitute the fastest growing segment of the population worldwide, leading to an expected increase in dementia cases. Education level and treatment of vascular risk factors has increased during the last decades. We examined whether this has influenced the prevalence of dementia according to DSM-III-R using population-based samples of 85-year-olds (N = 1065) examined with identical methods 1986–87 and 2008–10. The prevalence of dementia was 29.8% in 1986–87 and 21.7% in 2008–10 (OR 0.66; 95%-CI: 0.50–0.86). The decline was mainly observed for vascular dementia. The proportion with more than basic education (25.2% and 57.7%), and the prevalence of stroke (20% and 30%) increased, but the odds ratio for dementia with stroke decreased from 4.3 to 1.8 (interaction stroke*birth cohort; p = 0.008). In a logistic regression, education (OR 0.70; 95%-CI 0.51–0.96), stroke (OR 3.78; 95%-CI 2.28–6.29), interaction stroke*birth cohort (OR 0.50; 95%-CI 0.26–0.97), but not birth cohort (OR 0.98; 95%-CI 0.68–1.41), were related to prevalence of dementia. Thus, the decline in dementia prevalence was mainly explained by higher education and lower odds for dementia with stroke in later born birth cohorts. The findings may be related to an increased cognitive reserve and better treatment of stroke in later-born cohorts.

Temporal trend in dementia incidence since 2002 and projections for prevalence in England and Wales to 2040: modelling study

Objective To forecast dementia prevalence with a dynamic modelling approach that integrates calendar trends in dementia incidence with those for mortality and cardiovascular disease.Design Modelling study.Setting General adult population of England and Wales.Participants The English Longitudinal Study of Ageing (ELSA) is a representative panel study with six waves of data across 2002-13. Men and women aged 50 or more years, selected randomly, and their cohabiting partners were recruited to the first wave of ELSA (2002-03). 11392 adults participated (response rate 67%). To maintain representativeness, refreshment participants were recruited to the study at subsequent waves. The total analytical sample constituted 17 906 people. Constant objective criteria based on cognitive and functional impairment were used to ascertain dementia cases at each wave.Main outcome measures To estimate calendar trends in dementia incidence, correcting for bias due to loss to follow-up of study participants, a joint model of longitudinal and time-to-event data was fitted to ELSA data. To forecast future dementia prevalence, the probabilistic Markov model IMPACT-BAM (IMPACT-Better Ageing Model) was developed. IMPACT-BAM models transitions of the population aged 35 or more years through states of cardiovascular disease, cognitive and functional impairment, and dementia, to death. It enables prediction of dementia prevalence while accounting for the growing pool of susceptible people as a result of increased life expectancy and the competing effects due to changes in mortality, and incidence of cardiovascular disease.Results In ELSA, dementia incidence was estimated at 14.3 per 1000 person years in men and 17.0/1000 person years in women aged 50 or more in 2010. Dementia incidence declined at a relative rate of 2.7% (95% confidence interval 2.4% to 2.9%) for each year during 2002-13. Using IMPACT-BAM, we estimated there were approximately 767 000 (95% uncertainty interval 735 000 to 797 000) people with dementia in England and Wales in 2016. Despite the decrease in incidence and age specific prevalence, the number of people with dementia is projected to increase to 872 000, 1 092 000, and 1 205 000 in 2020, 2030, and 2040, respectively. A sensitivity analysis without the incidence decline gave a much larger projected growth, of more than 1.9 million people with dementia in 2040.Conclusions Age specific dementia incidence is declining. The number of people with dementia in England and Wales is likely to increase by 57% from 2016 to 2040. This increase is mainly driven by improved life expectancy.

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 individual's 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.

Trends in dementia prevalence, incidence, and survival rate in a Japanese community

OBJECTIVE

To investigate secular trends in the prevalence, incidence, and survival rate of dementia in a Japanese elderly population in a comprehensive manner.

METHODS

Five cross-sectional surveys of dementia were conducted among residents of a Japanese community, aged ≥65 years, in 1985, 1992, 1998, 2005, and 2012. We also established 2 cohorts consisting of the residents of this age group without dementia in 1988 (n = 803) and 2002 (n = 1,231), and each was followed for 10 years.

RESULTS

The age-standardized prevalence of all-cause dementia and Alzheimer disease (AD) increased with time (for all-cause dementia: 6.8% in 1985, 4.6% in 1992, 5.3% in 1998, 8.4% in 2005, and 11.3% in 2012, p for trend <0.01; for AD: 1.5%, 1.4%, 2.4%, 3.9%, and 7.2%, respectively, p for trend <0.01), while no secular change was observed for vascular dementia (VaD) (2.4%, 1.6%, 1.5%, 2.4%, and 2.4%, respectively, p for trend = 0.59). The age- and sex-adjusted incidence of all-cause dementia and AD, but not VaD, increased from the 1988 cohort to the 2002 cohort (for all-cause dementia: adjusted hazard ratio [aHR] 1.68, 95% confidence interval [CI] 1.38-2.06; for AD: aHR 2.07, 95% CI 1.59-2.70; for VaD: aHR 1.18, 95% CI 0.83-1.69). The 5-year survival rate of all-cause dementia and AD improved from the 1988 cohort to the 2002 cohort (for all-cause dementia: 47.3% to 65.2%; for AD: 50.7% to 75.1%; all p < 0.01).

CONCLUSIONS

The increased incidence and improved survival rate of AD could have resulted in the steep increase in AD prevalence in the Japanese elderly.

Real benefit of a protective factor against dementia: Importance of controlling for death. Example of sport practice

Objectives

To analyse the impact of a risk factor on several epidemiological indicators of death and dementia; the example of sport practice is presented.

Methods

A population of 3670 non-demented subjects living at home and aged 65 and older from the PAQUID study were followed for 22 years. Sport practice was documented at baseline. Dementia (according to DSM-III-R criteria) and death were assessed at each visit. Analyses were performed with an Illness-Death model, providing results on the risks of dementia and death, probabilities and life expectancies.

Results

A total of 743 subjects (20.2%) participated in regular sport practice. During the follow-up, the proportion of death was lower in the elderly people practicing sport (EPPS), whereas the proportion of incident dementia cases was the same. The adjusted model showed a decreased risk of dementia (HR = 0.84 (0.72–1.00)) and of death for non-demented subjects (HR = 0.61 (0.51–0.71)) for EPPS but a similar risk of death with dementia in both sport groups. The probability of remaining alive without dementia was higher in EPPS, whereas the probability of dying was lower. The mean lifetime without dementia was 3 years higher for the EPPS, but the mean lifetime with dementia was the same.

Discussion

A preventive measure on a protective factor that is more effective for preventing death than dementia could lead to an increased lifetime without dementia; however, the number of demented cases may remain unchanged, even if the risk of developing dementia is reduced. This dynamic is important to forecast the need for health care and social services for the elderly.

Midlife interventions are critical in prevention, delay, or improvement of Alzheimer's disease and vascular cognitive impairment and dementia

The basic strategy for focusing exclusively on genetically identified targets for intervening in late life dementias was formulated 30 years ago.  Three decades and billions of dollars later, all efforts at disease-modifying interventions have failed.  Over that same period, evidence has accrued pointing to dementias as late-life clinical phenotypes that begin as midlife pathologies.  Effective prevention therefore may need to begin in midlife, in order to succeed. No current interventions are sufficiently safe to justify their use in midlife dementia prevention trials.  Observational studies could be informative in testing the proposal that amyloid imaging and APOEε 4 genotype can predict those who are highly likely to develop Alzheimer’s disease and in whom higher risk interventions might be justifiable. A naturally occurring, diet-responsive cognitive decline syndrome occurs in canines that closely resembles human Alzheimer’s.  Canine cognitive dysfunction could be useful in estimating how early intervention must begin in order to succeed.  This model may also help identify and assess novel targets and strategies.  New approaches to dementia prevention are urgently required, since none of the world’s economies can sustain the costs of caring for this epidemic of brain failure that is devastating half of the over 85-year-olds globally.

Dementia incidence trend over 1992-2014 in the Netherlands: Analysis of primary care data

BACKGROUND

Recent reports have suggested declining age-specific incidence rates of dementia in high-income countries over time. Improved education and cardiovascular health in early age have been suggested to be bringing about this effect. The aim of this study was to estimate the age-specific dementia incidence trend in primary care records from a large population in the Netherlands.

METHODS AND FINDINGS

A dynamic cohort representative of the Dutch population was composed using primary care records from general practice registration networks (GPRNs) across the country. Data regarding dementia incidence were obtained using general-practitioner-recorded diagnosis of dementia within the electronic health records. Age-specific dementia incidence rates were calculated for all persons aged 60 y and over; negative binomial regression analysis was used to estimate the time trend. Nine out of eleven GPRNs provided data on more than 800,000 older people for the years 1992 to 2014, corresponding to over 4 million person-years and 23,186 incident dementia cases. The annual growth in dementia incidence rate was estimated to be 2.1% (95% CI 0.5% to 3.8%), and incidence rates were 1.08 (95% CI 1.04 to 1.13) times higher for women compared to men. Despite their relatively low numbers of person-years, the highest age groups contributed most to the increasing trend. There was no significant overall change in incidence rates since the start of a national dementia program in 2003 (-0.025; 95% CI -0.062 to 0.011). Increased awareness of dementia by patients and doctors in more recent years may have influenced dementia diagnosis by general practitioners in electronic health records, and needs to be taken into account when interpreting the data.

CONCLUSIONS

Within the clinical records of a large, representative sample of the Dutch population, we found no evidence for a declining incidence trend of dementia in the Netherlands. This could indicate true stability in incidence rates, or a balance between increased detection and a true reduction. Irrespective of the exact rates and mechanisms underlying these findings, they illustrate that the burden of work for physicians and nurses in general practice associated with newly diagnosed dementia has not been subject to substantial change in the past two decades. Hence, with the ageing of Western societies, we still need to anticipate a dramatic absolute increase in dementia occurrence over the years to come.

Is the time ripe for new diagnostic criteria of cognitive impairment due to cerebrovascular disease? Consensus report of the International Congress on Vascular Dementia working group

BACKGROUND

Long before Alzheimer's disease was established as the leading cause of dementia in old age, cerebrovascular lesions were known to cause cognitive deterioration and associated disability. Since the middle of the last century, different diagnostic concepts for vascular dementia and related syndromes were put forward, yet no widely accepted diagnostic consensus exists to date.

DISCUSSION

Several international efforts, reviewed herein, are ongoing to define cognitive impairment due to cerebrovascular disease in its different stages and subtypes. The role of biomarkers is also being discussed, including cerebrospinal fluid proteins, structural and functional brain imaging, and genetic markers. The influence of risk factors, such as diet, exercise and different comorbidities, is emphasised by population-based research, and lifestyle changes are considered for the treatment and prevention of dementia.

CONCLUSION

To improve the diagnosis and management of vascular cognitive impairment, further progress has to be made in understanding the relevant pathomechanisms, including shared mechanisms with Alzheimer's disease; bringing together fragmented research initiatives in coordinated international programs; testing if known risk factors are modifiable in prospective interventional studies; and defining the pre-dementia and pre-clinical stages in line with the concept of mild cognitive impairment due to Alzheimer's disease.

Simultaneous temporal trends in dementia incidence and prevalence, 2005-2013: a population-based retrospective cohort study in Saskatchewan, Canada

BACKGROUND

Original studies published over the last decade regarding time trends in dementia report mixed results. The aims of the present study were to use linked administrative health data for the province of Saskatchewan for the period 2005/2006 to 2012/2013 to: (1) examine simultaneous temporal trends in annual age- and sex-specific dementia incidence and prevalence among individuals aged 45 and older, and (2) stratify the changes in incidence over time by database of identification.

METHODS

Using a population-based retrospective cohort study design, data were extracted from seven provincial administrative health databases linked by a unique anonymized identification number. Individuals 45 years and older at first identification of dementia between April 1, 2005 and March 31, 2013 were included, based on case definition criteria met within any one of four administrative health databases (hospital, physician, prescription drug, and long-term care).

RESULTS

Between 2005/2006 and 2012/2013, the 12-month age-standardized incidence rate of dementia declined significantly by 11.07% and the 12-month age-standardized prevalence increased significantly by 30.54%. The number of incident cases decreased from 3,389 to 3,270 and the number of prevalent cases increased from 8,795 to 13,012. Incidence rate reductions were observed in every database of identification.

CONCLUSIONS

We observed a simultaneous trend of decreasing incidence and increasing prevalence of dementia over a relatively short 8-year time period from 2005/2006 to 2012/2013. These trends indicate that the average survival time of dementia is lengthening. Continued observation of these time trends is warranted given the short study period.

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

BACKGROUND

Current 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.

METHODS

We carried out a systematic review of studies of trends in prevalence, incidence and mortality for people with dementia, conducted since 1980.

RESULTS

We 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.

CONCLUSIONS

We 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.

Alzheimer's disease prevention: A way forward

This review proposes a more optimistic view of Alzheimer's disease (AD), in contrast to that contributed by the ageing of the population and the failure of potentially curative therapies (vaccines and others). Treatment failure is likely due to the fact that AD gestates in the brain for decades but manifests in old age. This review updates the concept of AD and presents the results of recent studies that show that primary prevention can reduce the incidence and delay the onset of the disease. Half of all cases of AD are potentially preventable through education, the control of cardiovascular risk factors, the promotion of healthy lifestyles and specific drug treatments. These approaches could substantially reduce the future incidence rate of this disease.

A two decade dementia incidence comparison from the Cognitive Function and Ageing Studies I and II

Dramatic global increases in future numbers of people with dementia have been predicted. No multicentre population-based study powered to detect changes over time has reported dementia incidence. MRC Cognitive Function and Ageing Study (CFAS) undertook baseline interviews in populations aged 65+ years in England and Wales (1989–1994). Three areas (CFAS I) were selected for new sampling two decades later (2008–2011) with same geographical boundaries, sampling and approach methods (CFAS II). At 2 years CFAS I interviewed 5,156 (76% response) with 5,288 interviewed in CFAS II (74% response). Here we report a 20% drop in incidence (95% CI: 0–40%), driven by a reduction in men across all ages above 65. In the UK we estimate 209,600 new dementia cases per year. This study was uniquely designed to test for differences across geography and time. A reduction of age-specific incidence means that the numbers of people estimated to develop dementia in any year has remained relatively stable.

Future dramatic rises in dementia are widely reported, assuming no change in incidence. Matthews and colleagues report that, in contrast to such statements, age-specific incidence has dropped over 20 years, with overall incidence of dementia remaining stable in a large multi-site population study from England.

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.