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The Global Impact of Dementia: 2013-2050

Authors:
Martin Prince at King's College London
Martin Prince
Maëlenn Guerchet at French National Research Institute for Sustainable Development
Maëlenn Guerchet
  • French National Research Institute for Sustainable Development
Matthew Prina at Newcastle University
Matthew Prina
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Policy Brief for Heads of Government
The Global Impact of Dementia 2013–2050
ALZHE IMER’S DISE ASE INTERNATIONAL · TH E GLOBAL VOIC E ON DEMENTI A
Introduction
Alzheimer’s Disease International (ADI) published
global prevalence data on dementia in the World
Alzheimer Report 2009 1 based on a systematic
review of 154 studies conducted worldwide, and
United Nations population projections through to
the year 2050. We estimated 36 million people with
dementia in 2010, nearly doubling every 20 years to
66 million by 2030 and to 115 million by 2050.
Key findings included
• 58% of those affected lived in low and middle
income countries, underlining the high impact of
the condition in those regions, where awareness
is low, health and social care are poorly
developed and social protection is limited.
• Population ageing is the main driver of projected
increases.
• We assumed that age-specific prevalence
would remain constant. This assumption is
challenged by recent evidence suggesting a
modest recent decline in dementia prevalence
in some higher income countries (HIC), but an
increase in prevalence in China, likely linked to
recent changes in population health, particularly
exposure to cardiovascular risk factors.
• Since population ageing is occurring at an
unprecedentedly fast rate in middle income
countries, the bulk of the increase in numbers
through to 2050 will occur in those regions. By
2050 71% of those with dementia would be living
in what are currently lower and middle-income
countries (LMIC).
The Global Impact of Dementia 2013–2050
Although high income countries, including the G8, have borne the brunt of the dementia
epidemic, this is a global phenomenon. Most people with dementia live in low and
middle income countries, and most of the dramatic increases in numbers affected,
through to 2050, will occur in those regions. In a spirit of international cooperation and
solidarity we urge the G8 governments to sponsor intergovernmental action to make
dementia a global priority. Crucially, this must include opening up access to diagnosis
and current evidence-based treatment and care. All countries worldwide are failing in
this basic objective. Action to address this problem should be balanced, as a priority,
with research to improve treatment options and quality of care.
Since 2009, the global evidence base has
expanded, most particularly with a new
systematic review of the prevalence of
dementia in China 3 comprising 75 studies,
most published in Chinese language journals,
and with seven studies from five sub-
Saharan African countries, where previously
only one study from Nigeria had been
available.
The G8 Dementia Summit on 11 December
2013 provides a timely opportunity to
reassess and update evidence on the scale
and the distribution of the global dementia
epidemic, in particular its impact on more
developed (G8, G20, OECD and ‘high
income’ countries) and less developed ‘low
and middle income’ countries.
For the current update, we carried out a
limited review, focusing on the new evidence
emerging from China and the sub-Saharan
African regions, and applied the new
prevalence proportions to the latest (2012)
UN population projections 2. Details of the
methodology are provided in Annex 1.
The work on this report has been a joint
effort of the Global Observatory for Ageing
and Dementia Care (Prof Martin Prince,
Dr Maëlenn Guerchet and Dr Matthew Prina),
and the ADI office.
2
Figure 1 Original (2009 World Alzheimer Report) and updated age-specific prevalence of dementia (%) by region,
showing impact of new data from Asia East (China) and Sub-Saharan Africa
Results
The prevalences of dementia estimated from the
recent more comprehensive review and meta-
analysis of China studies 3 and our own meta-
analysis of studies from sub-Saharan Africa were
substantially higher than those used in the 2009
World Alzheimer Report. Age-standardised to a
standard West European population, prevalence
for East Asia increased from 4.98% to 6.99%
and in the sub-Saharan African regions from a
range of 2.07% to 4.00%, to 4.76% (Figure 1).
The net effect, as more data becomes available,
is to further reduce the variation in prevalence
between world regions.
The number of people living with dementia
worldwide in 2013 is estimated at 44.35 million,
reaching 75.62 million in 2030 and 135.46 million
in 2050 (Figure 2). The updated estimates are
higher than our original estimates reported in the
2009 World Alzheimer Report, by 15% in 2030,
and by 17% in 2050.
0
2
5
7
9
Australasia
Asia Pacific
Oceania
Asia E
Asia S
Asia SE
Asia Central
Europe W
Europe Central
Europe E
America N
Caribbean
Latin America
N Africa/ Middle East
SSA W
SSA E
SSA Central
SSA S
Standard Prevalence (%)
Updated
Original
0
35
70
105
140
2010 2013 2030 2050
Original
Updated
People with dementia (millions)
36
million
66
million
115
million
44
million
76
million
135
million
Figure 2 Increase in numbers of people with dementia worldwide (2010-2050), comparing original and
updated estimates
3POLICY BRI EF FOR HEADS OF GOVERNM ENT: THE GLOBAL IMPACT OF DEME NTIA 2013–2050
ALZHE IMER’S DISE ASE INTERNATIONAL · TH E GLOBAL VOIC E ON DEMENTI A
The largest increases in projected numbers of
people with dementia are those for the Asia East
and Sub-Saharan African regions, accounted
for by the higher age-specific prevalence of
dementia estimated in our new reviews of survey
data from those regions (Annex 2). Hence, in
2050 we are now estimating 33.61 million people
with dementia in Asia East (an increase of 49%
from the previous estimate of 22.54 million) and
5.05 million older people with dementia in SSA
(an increase of 136% from the previous estimate
of 2.14 million). However, the new estimates of
numbers of people with dementia are higher for
all GBD regions than those estimated in 2009.
This is explained by the underestimation of
current numbers of older people in the previous
UN population estimates (affecting the 2013
figures), and revision upwards of probability of
survival into older age (affecting the 2030 and
2050 projections).
We now estimate that while 32% of people
with dementia live in G8 countries and 38%
in high income countries, 62% live in low and
middle income countries (Table 1). By 2050, the
proportion living in G8 countries will have shrunk
to 21%, while the proportion living in what are
currently low and middle income countries will
have increased to 71%.
Region
People with dementia millions
(% of world total)
Proportionate increase
(%)
2013 2030 2050 2013-2030 2013-2050
G8 14.02 (32%) 20.38 (27%) 28.91 (21%) 45 106
G20 33.93 (76%) 56.40 (75%) 96.61 (71%) 66 185
OECD 18.08 (41%) 27.98 (37%) 43.65 (32%) 55 142
High income 17.00 (38%) 25.86 (34%) 39.19 (29%) 52 131
Low and middle income 27.84 (62%) 49.76 (66%) 96.27 (71%) 79 246
World 44.35 75.62 135.46 71 205
0
25
50
75
100
125
150
2013 2015 2020 2025 2030 2035 2040 2045 2050
Low and middle income countries
High income countries
Millions of people with dementia
Year
Table 1 Updated estimates of the number of people with dementia living in G8, G20,
OECD, LMIC and HIC countries, and as a percentage of world total
Figure 3 Number of people with dementia in low and middle income countries
compared to high income countries
4
diagnosis; case management across the
course of the illness; support, education and
training for carers; optimising physical health;
acetylcholinesterase inhibitors; cognitive
stimulation; and non-pharmacological
interventions for behavioural disturbance.
Currently less than half of those in high
income countries and fewer than 10% of
those in LMIC have received a dementia
diagnosis.
8 There are lessons to be drawn from the
HIV epidemic. First, new and dramatically
effective treatments can only be scaled up
when diagnostic and care systems are well
established. Second, affordable access
to new diagnostic technologies and drug
therapies will need rapidly to be extended
to low and middle income country markets,
where most of those who might benefit live.
Third, those countries that where involved
in ‘global trials’ should also benefit from
treatments being made available at subsidised
cost with adequate standards of care in place.
9 ADI and the World Health Organization have,
in their joint report Dementia: a public health
priority 1 3, called upon all Governments to
make dementia a public and health priority. As
part of this process, all governments should
initiate national debates regarding the future
provision and financing of long-term care
(see World Alzheimer Report 2013: Journey
of Caring 1 5 ). However, most are woefully
unprepared for the dementia epidemic with
only 13 countries having funded and sought to
implement a national dementia plan. Without
a plan, the risk is that health and social care
systems will not cope with the increase
in numbers and operate in crisis mode,
escalating costs even further.
10 At the eve of the G8 Dementia Summit in
London, UK, it is not just the G8 countries,
but all nations that must commit to a
sustained increase in dementia research and
a comprehensive plan for collaborative action
involving all relevant government sectors,
industry and civil society. International
cooperation will be essential. There is a
need for a collaborative, global action plan
for governments, industry and non-profit
organisations like Alzheimer associations.
Priorities include; breaking down barriers to
effective research; promoting rapid translation
and ensuring equitable access to promising
technologies and treatments; technical
support for policymaking, health and social
care service and system development.
1 Dementia, including Alzheimer’s disease,
is one of the biggest global public health
challenges facing our generation. Newly
available data suggests that the current
burden and future impact of the dementia
epidemic has been underestimated,
particularly for the Asia East and Sub-Saharan
African regions.
2 This is a global epidemic – although cases
are disproportionately concentrated in the
world’s richest and most demographically
aged countries, already the clear majority
(62%) of people with dementia live in low and
middle income countries where access to
social protection, services, support and care
are very limited.
3 In the next few decades, the global burden
of dementia will shift inexorably to poorer
countries, particularly rapidly developing
middle income countries that are members of
the G20, but not the G8.
4 The future scale of the dementia epidemic
may be blunted through improvements in
population health, but our best estimates
suggest that only up to 10% of incidence
may thus be avoided 1 3. Public health and
disease control measures targeting smoking,
underactivity, obesity, hypertension and
diabetes should be prioritised. Education and
other factors that enhance brain and cognitive
development will also improve the brain health
of those entering old age, and reduce the
incidence of dementia in late life.
5 Standard & Poor’s has described global
population ageing as the biggest threat to
the sustainability of sovereign debt. Among
the chronic diseases, dementia makes by far
the largest single contribution to disability
and needs for care among older people. The
current (2010) global societal economic cost
of dementia is US$ 604 billion, or 1% of global
GDP 14 . Costs will escalate proportionately
with numbers affected, and with increased
demand for formal care services, particularly
in low and middle income countries 13 .
6 Research must be a global priority if we
are to improve the quality and coverage of
care, find treatments that alter the course of
the disease, and identify more options for
prevention.
7 Investment in the search for a cure must be
balanced with initiatives to improve access
to currently available evidence-based
packages of care – these include timely
Conclusions and implications
5POLICY BRI EF FOR HEADS OF GOVERNM ENT: THE GLOBAL IMPACT OF DEME NTIA 2013–2050
ALZHE IMER’S DISE ASE INTERNATIONAL · TH E GLOBAL VOIC E ON DEMENTI A
Estimation of the number of people with
dementia
The new rates were applied to the new UN population
estimates for each 5-years age band (60-64, to 100 and
over) 2. When rates were not available for one age-band
(i.e. over 90 in SSA and over 100 in China), the rate of
the nearest age-band was applied. As gender-specific
estimates were available neither for China nor SSA,
we applied the age-specific estimates to the whole
population and to each gender separately. In the East Asia
region – composed of China, Hong Kong SAR, Macao
SAR, Chinese Taipei and DPR Korea – the new rates were
applied to mainland China, Hong Kong SAR and Macao
SAR, whereas the East Asia rates from the 2009 Word
Alzheimer Report were maintained for the DPR Korea and
Chinese Taipei.
For Sub-Saharan Africa, the new rates were applied to
the countries belonging to the following Global Burden
Disease (GBD) regions: SSA West, SSA Central, SSA East
and SSA Southern. Based on the GBD regions, Algeria
belongs to the North Africa / Middle East, so we therefore
applied the EMRO B rates that are used for some of its
neighbours.
For all the other regions, we applied the rates found in
the 2009 World Alzheimer Report to the new population
estimates from the United Nations 2.
Annex 1: Methods
The prevalence of dementia in China and
Sub-Saharan Africa
The estimates for China were revised based on the recent
meta-analysis published by Chan et al. 3 . This meta-
analysis included repor ts for dementia or Alzheimer’s
Disease in mainland China, published in Chinese and
English between 1990 and 2010. The rates applied to the
population estimates were the age-specific prevalence of
dementia in 2010. A new systematic review of dementia
in China has also been recently published 4 , together with
a new large multi-centre population-based prevalence
study of dementia in China 5. These studies were not
taken into account in our estimates, but will be included in
any future updates.
For Sub-Saharan Africa, we conducted a systematic
review of the literature on the prevalence of dementia with
Pubmed / Medline up to October 2013 using a similar
methodology and inclusion criteria that we used for the
2009 World Alzheimer Report 1 (see online appendix).
We sought and included population-based studies of the
prevalence of dementia among people aged 60 years
and over for which the fieldwork started on or after 1st
January 1980. Prevalence rates were extracted for seven
studies covering five different countries 6- 12 . A random
effect exponential (Poisson) model was used to assess
the effects of age on the prevalence of dementia. We
then applied the relevant mean ages to the coefficients
estimated from the model, to estimate prevalence in five
year age-bands from 65-69 years to 85 years and over,
for both sexes combined.
References
1 Alzheimer’s Disease International: World Alzheimer
Report 2009. 2009.
2 United Nations Department of Economic and
Social Affairs Population Division: World Population
Prospects: The 2012 Revision, DVD Edition. 2013.
3 Chan KY, Wang W, Wu JJ, Liu L, Theodoratou E, Car
J, Middleton L, Russ TC, Deary IJ, Campbell H et al:
Epidemiology of Alzheimer’s disease and other forms
of dementia in China, 1990-2010: a systematic review
and analysis. The Lancet 2013, 381(9882):2016-2023.
4 Wu YT, Lee HY, Norton S, Chen C, Chen H, He C,
Fleming J, Matthews FE, Brayne C: Prevalence
studies of dementia in mainland china, Hong Kong
and taiwan: a systematic review and meta-analysis.
PLoS ONE 2013, 8(6):e66252.
5 Jia J, Wang F, Wei C, Zhou A, Jia X, Li F, Tang M, Chu
L, Zhou Y, Zhou C et al: The prevalence of dementia
in urban and rural areas of China. Alzheimers Dement
2013.
6 Hendrie HC, Osuntokun BO, Hall KS, Ogunniyi AO,
Hui SL, Unverzagt FW, Gureje O, Rodenberg CA,
Baiyewu O, Musick BS: Prevalence of Alzheimer’s
disease and dementia in two communities: Nigerian
Africans and African Americans. Am J Psychiatry
1995, 152(10):1485-1492.
7 Guerchet M, Houinato D, Paraiso MN, von Ahsen
N, Nubukpo P, Otto M, Clement JP, Preux PM,
Dartigues JF: Cognitive impairment and dementia
in elderly people living in rural Benin, west Africa.
Dement Geriatr Cogn Disord 2009, 27(1):34-41.
8 Guerchet M, M’Belesso P, Mouanga AM, Bandzouzi B,
Tabo A, Houinato DS, Paraiso MN, Cowppli-Bony P,
Nubukpo P, Aboyans V et al: Prevalence of dementia in
elderly living in two cities of Central Africa: the EDAC
survey. Dement Geriatr Cogn Disord 2010, 30(3):261-268.
9 Paraiso MN, Guerchet M, Saizonou J, Cowppli-Bony
P, Mouanga AM, Nubukpo P, Preux PM, Houinato DS:
Prevalence of dementia among elderly people living
in Cotonou, an urban area of Benin (West Africa).
Neuroepidemiology 2011, 36(4):245-251.
10 Yusuf AJ, Baiyewu O, Sheikh TL, Shehu AU: Prevalence
of dementia and dementia subtypes among community-
dwelling elderly people in northern Nigeria. Int
Psychogeriatr 2011, 23(3):379-386.
11 Longdon AR, Paddick SM, Kisoli A, Dotchin C, Gray
WK, Dewhurst F, Chaote P, Teodorczuk A, Dewhurst M,
Jusabani AM et al: The prevalence of dementia in rural
Tanzania: a cross-sectional community-based study. Int J
Geriatr Psychiatr y 2013, 28(7):728-737.
12 Guerchet M, Banzouzi-Ndamba B, Mbelesso P, Pilleron
S, Clement J-P, Dartigues J-F, Preux P-M.: Prevalence of
dementia in two countries of Central Africa: comparison
or rural and urban areas in the EPIDEMCA study.
Neuroepidemiology 2013, 41:223-316.
13 World Health Organization and Alzheimer’s Disease
International, Dementia: a public health priority, Geneva
April 2012, http://www.alz.co.uk/WHO-dementia-report
14 Wimo A, Prince M. World Alzheimer Report 2010; The
Global Economic Impact of Dementia. 2010. London,
Alzheimer’s Disease International
15 World Alzheimer Repor t 2013, Journey of Caring, An
analysis of long-term care for dementia, http://www.alz.
co.uk/research/world-report-2013
6
Annex 2
GBD Region
Original estimates (2009) Updated estimates Proportionate increases
(%) for new estimates
2010 2030 2050 2013 2030 2050 2013- 2030 2013- 2050
Asia/Pacific 15 .9 4 33.04 60.92 21.87 39.7 9 71.8 4 82 228
Australasia 0.31 0.53 0.79 0.37 0.62 1.02 68 176
Asia Pacific High Income 2.83 5.36 7. 0 3 3.26 5.50 7. 5 8 69 13 3
Oceania 0.02 0.04 0.10 0.02 0.04 0.09 100 350
Asia Central 0.33 0.56 1.19 0.29 0.44 0.88 52 203
Asia East 5.49 11.93 22.54 10.46 18. 83 33.61 80 221
Asia South 4.48 9.31 18.12 4 .74 8.50 16.61 79 250
Asia Southeast 2.48 5.30 11.13 2.74 5.87 12.0 5 114 340
Europe 9.95 13. 95 18. 65 10.93 14.8 20.75 35 90
Europe Central 1.10 1.57 2.10 1.23 1.69 2.29 37 86
Europe Eastern 1.87 2.36 3 .10 1.8 6 2.03 2.44 931
Europe Western 6.98 10.03 13.4 4 7. 84 11.08 16.02 41 10 4
The Americas 7. 8 2 14.78 2 7. 0 8 8.77 15.8 30.51 80 248
North America High Income 4.38 7.13 11.01 4.58 7. 2 8 11.74 59 156
Caribbean 0.33 0.62 1.0 4 0.38 0.63 1.14 66 200
Latin America Andean 0.25 0.59 1.2 9 0.31 0.64 1.4 6 106 371
Latin America Central 1.19 2.79 6.37 1.3 8 2.95 7. 07 114 412
Latin America Southern 0.61 1.0 8 1.83 0.71 1.17 2.13 65 200
Latin America Tropical 1.05 2.58 5.54 1.42 3.13 6.97 120 391
Africa 1.8 6 3.92 8.74 2.78 5.24 12.3 5 88 344
North Africa / Middle East 1.15 2.59 6 .19 1. 47 2.91 7. 29 98 396
Sub-Saharan Africa Central 0.07 0.12 0.24 0.13 0.23 0.48 77 269
Sub-Saharan Africa East 0.36 0.69 1.3 8 0.55 1.0 6 2.45 93 345
Sub-Saharan Africa Southern 0 .10 0.17 0.20 0.19 0.29 0.49 53 15 8
Sub-Saharan Africa West 0 .18 0.35 0.72 0.44 0.76 1.63 73 270
World 35.56 65.69 115 .38 44.35 75.62 135.46 71 205
Table 1 Numbers of people with dementia according to GBD regions (in millions, by year)
Acknowledgements
Authors
Prof Martin Prince *
Dr Maëlenn Guerchet *
Dr Matthew Prina *
Alzheimer’s Disease International
* Global Observatory for Ageing and Dementia Care,
Health Service and Population Research Department, King’s College London
Thanks to
Pr Richard Walker, Dr Catherine Dotchin and Dr William Keith Gray from the Northumbria Healthcare NHS Foundation
Trust, the Institute for Ageing and Health, and the Institute of Health and Society, in Newcastle University (UK) for providing
us prevalence rates from their study in Tanzania.
Pr Pierre-Marie Preux, from the UMR Inserm 1094 Tropical Neuroepidemiology in Limoges (France), and the EPIDEMCA
group, for allowing us to include their last results in Central Africa before their publication.
Cover image © Barbara Kinney, used with permission of Alzheimer’s Association (US).
Policy Brief for Heads of Government: The Global Impact of Dementia 2013–2 050
Published by Alzheimer’s Disease International (ADI), London. December 2013
Copyright © Alzheimer’s Disease International
7POLICY BRI EF FOR HEADS OF GOVERNM ENT: THE GLOBAL IMPACT OF DEME NTIA 2013–2050
ALZHE IMER’S DISE ASE INTERNATIONAL · TH E GLOBAL VOIC E ON DEMENTI A
Alzheimer’s Disease International:
The International Federation
of Alzheimer’s Disease and
Related Disorders Societies, Inc.
is incorporated in Illinois, USA,
and is a 501(c)(3) not-for-profit
organization
Alzheimer’s Disease International
64 Great Suffolk Street
London SE1 0BL
UK
Tel: +44 20 79810880
Fax: +44 20 79282357
www.alz.co.uk
About Alzheimer’s Disease International
Alzheimer’s Disease International (ADI) is the international federation of Alzheimer
associations throughout the world. Each of our 79 members is a non-profit
Alzheimer association supporting people with dementia and their families.
ADI was founded in 1984 and registered as a non-profit organization in the USA.
Based in London, ADI is in official relations with the WHO since 1996 and has
consultative status with the UN since 2012.
ADI’s vision is an improved quality of life for people with dementia and their
families throughout the world. ADI aims to make dementia a global health priority,
to build and strengthen Alzheimer associations, and to raise awareness about
dementia worldwide. Stronger Alzheimer associations are better able to meet the
needs of people with dementia and their carers, and to be the global voice on
dementia.
Global Observatory for Ageing and Dementia Care
The Global Observatory for Ageing and Dementia Care, hosted at the Health
Service and Population Research Department, King’s College London, was
founded in 2013. Supported by Alzheimer’s Disease International and King’s
College London, the Observatory aims to synthesise global evidence for
policymakers and the public through high impact evidence-based reports for
Alzheimer’s Disease International (World Alzheimer Reports 2009, 2010, 2011 and
2013), the World Health Organization (Dementia; a public health priority) and other
relevant intergovernmental organisations. A particular focus is to identify and
promote effective innovations in health and social care policy and practice.
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Full-text available
  • Nov 2023
Introduction This study investigates whether plasma biomarkers (Aβ42/40 and p‐tau 181), APS, as well as apolipoprotein E (APOE) proteotype predict cognitive deficits in elderly adults from the Democratic Republic of Congo. Methods Forty‐four with possible AD (pAD) and 41 healthy control (HC) subjects were screened using CSID and AQ, underwent cognitive assessment with the African Neuropsychology Battery (ANB), and provided blood samples for plasma Aβ42, Aβ40, Aβ42/40, and APOE proteotype. Linear and logistic regression were used to evaluate the associations of plasma biomarkers with ANB tests and the ability of biomarkers to predict cognitive status. Results Patients with pAD had significantly lower plasma Aβ42/40 levels, higher APS, and higher prevalence of APOE E4 allele compared to HC. Groups did not differ in levels of Aβ40, Aβ42, or P‐tau 181. Results showed that Aβ42/40 ratio and APS were significantly associated with African Naming Test (ANT), African List Memory Test (ALMT), and African Visuospatial Memory Test (AVMT) scores, while the presence of APOE E4 allele was associated with ANT, ALMT, AVMT, and APT scores. P‐tau 181 did not show any significant associations while adjusting for age, education, and gender. APS showed the highest area under the curve (AUC) value (AUC = 0.78, 95% confidence interval [CI]: 0.68–0.88) followed by Aβ42/40 (AUC = 0.75, 95% CI: 0.66–0.86) and APOE E4 (AUC = 0.69 (CI 0.57–0.81) in discriminating pAD from HC. Discussion These results demonstrate associations between select plasma biomarker of AD pathology (Aβ42/40), APS, and APOE E4 allele) and ANB test scores and the ability of these biomarkers to differentiate pAD from cognitively normal SSA individuals, consistent with findings reported in other settings.
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Sensitivity of the African Neuropsychology Battery Memory Subtests and Learning Slopes in Discriminating APOE 4 and Amyloid Pathology in Adult Individuals in the Democratic Republic of Congo
Preprint
  • Oct 2023
Background: The current study examined the sensitivity of two memory subtests and their corresponding learning slope metrics derived from the African Neuropsychology Battery (ANB) to detect amyloid pathology and APOE4 status in adults from Kinshasa, the Democratic Republic of the Congo. Methods: 85 participants were classified for the presence of β-amyloid pathology and based on allelic presence of APOE4. All participants were screened using CSID and AQ, underwent verbal and visuospatial memory testing from ANB, and provided blood samples for plasma Aβ42, Aβ40, and APOE proteotype. Pearson correlation, linear and logistic regression were conducted to compare amyloid pathology and APOE4 status with derived learning scores, including initial learning, raw learning score, learning over trials, and learning ratio. Results: Our sample included 35 amyloid positive and 44 amyloid negative individuals as well as 42 without and 39 with APOE4. All ROC AUC ranges for the prediction of amyloid pathology based on learning scores were low, ranging between 0.56-0.70 (95% CI ranging from 0.44-0.82). The sensitivity of all the scores ranged between 54.3-88.6, with some learning metrics demonstrating good sensitivity. Regarding APOE4 prediction, all AUC values ranged between 0.60-0.69, with all sensitivity measures ranging between 53.8-89.7. There were minimal differences in the AUC values across learning slope metrics, largely due to the lack of ceiling effects in this sample. Discussion: This study demonstrates that some ANB memory subtests and learning slope metrics can discriminate those that are normal from those with amyloid pathology and those with and without APOE4, consistent with findings reported in Western populations.
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Evaluation of the relationship among gene expressions and enzyme activities with antioxidant role and presenilin 1 expression in Alzheimer's disease
Article
Full-text available
  • Sep 2023
It is known that oxidative stress originating from reactive oxygen species plays a role in the pathogenesis of Alzheimer's disease. In this study, the role of antioxidant status associated with oxidative stress in Alzheimer's disease was investigated. Peripheral blood samples were obtained from 28 healthy individuals (as control) and 28 Alzheimer's patients who met the National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association criteria. Catalase, glutathione S‐transferase and paraoxonase 1 enzyme activities in blood plasma and glutathione S‐transferase enzyme activities in erythrocytes were determined by spectrophotometer. Catalase, glutathione S‐transferase and presenilin 1 gene expressions in leukocytes were determined using qRT‐PCR. Data were analysed with SPSS one‐way anova , a LSD post hoc test at p < 0.05. The activity of each enzyme was significantly reduced in Alzheimer's patients compared to control. The catalase gene expression level did not change compared to the control. Glutathione S‐transferase and presenilin 1 gene expression levels were increased compared to the control.
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Cardiovascular health and cognitive outcomes: Findings from a biracial population-based study in the United States
Article
Introduction: The aim of this study was to evaluate the association of cardiovascular health (CVH) with cognitive outcomes, including incident Alzheimer's dementia, rate of cognitive decline, and measures of brain injury and structure. Methods: This study consisted of 1702 Black or African American and White participants living in the south side of Chicago, Illinois, and enrolled in the Chicago Health and Aging Project, a population-based cohort since 1993. CVH was based on seven risk factors, including diet, physical activity, body mass index, smoking, dyslipidemia, hypertension, and diabetes. Results: In a multivariable-adjusted model, CVH was associated with a lower risk of Alzheimer's dementia. The hazard ratio per 1 additional point in CVH score was 0.84 (95% CI 0.76, 0.94). CVH was also associated with a slower rate of cognitive decline and less volume (injury) in white matter hyperintensities. Discussion: Promoting CVH in communities with Black residents may lower the future risk of Alzheimer's dementia.
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Machine learning algorithms for identifying predictive variables of mortality risk following dementia diagnosis: A longitudinal cohort study
Article
Full-text available
  • Jun 2023
Background: Machine learning (ML) could have advantages over traditional statistical models in identifying risk factors. Using ML algorithms, our objective was to identify the most important variables associated with mortality after dementia diagnosis in the Swedish Registry for Cognitive/Dementia Disorders (SveDem). Methods: From SveDem, a longitudinal cohort of 28,023 dementia-diagnosed patients was selected for this study. Sixty variables were considered as potential predictors of mortality risk, such as age at dementia diagnosis, dementia type, sex, body mass index (BMI), mini-mental state examination (MMSE) score, time from referral to initiation of work-up, time from initiation of work-up to diagnosis, dementia medications, comorbidities, and some specific medications for chronic comorbidities (e.g., cardiovascular disease). We applied sparsity-inducing penalties for three ML algorithms and identified twenty important variables for the binary classification task in mortality risk prediction and fifteen variables to predict time to death. Area-under-ROC curve (AUC) measure was used to evaluate the classification algorithms. Then, an unsupervised clustering algorithm was applied on the set of twenty-selected variables to find two main clusters which accurately matched surviving and dead patient clusters. Results: A support-vector-machine (SVM) with an appropriate sparsity penalty provided the classification of mortality risk with accuracy=0.7077, AUC=0.7375, sensitivity=0.6436, and specificity=0.740. Across three ML algorithms, the majority of the identified twenty variables were compatible with literature and with our previous studies on SveDem. We also found new variables which were not previously reported in literature as associated with mortality in dementia. Performance of basic dementia diagnostic work-up, time from referral to initiation of work-up, and time from initiation of work-up to diagnosis were found to be elements of the diagnostic process identified by the ML algorithms. The median follow-up time was 1053 (IQR=516-1771) days in surviving and 1125 (IQR=605-1770) days in dead patients. For prediction of time to death, the CoxBoost model identified fifteen variables and classified them in order of importance. These highly important variables were age at diagnosis, MMSE score, sex, BMI, and Charlson Comorbidity Index (CCI) with selection scores of 23%, 15%, 14%, 12% and 10%, respectively. Conclusions: This study demonstrates the potential of sparsity-inducing ML algorithms in improving our understanding of mortality risk factors in dementia patients and their application in clinical settings. Moreover, ML methods can be used as a complement to traditional statistical methods. Keywords: Dementia, Mortality, Prediction Model, Machine Learning, Cohort Study
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The prevalence of dementia in urban and rural areas of China
Article
Full-text available
The Chinese population has been aging rapidly and the country's economy has experienced exponential growth during the past three decades. The goal of this study was to estimate the changes in the prevalence of dementia, Alzheimer's disease (AD), and vascular dementia (VaD) among elderly Chinese individuals and to analyze differences between urban and rural areas. For the years 2008 to 2009, we performed a population-based cross-sectional survey with a multistage cluster sampling design. Residents aged 65 years and older were drawn from 30 urban (n = 6096) and 45 rural (n = 4180) communities across China. Participants were assessed with a series of clinical examinations and neuropsychological measures. Dementia, AD, and VaD were diagnosed according to established criteria via standard diagnostic procedures. The prevalence of dementia, AD, and VaD among individuals aged 65 years and older were 5.14% (95% CI, 4.71-5.57), 3.21% (95% CI, 2.87-3.55), and 1.50% (95% CI, 1.26-1.74), respectively. The prevalence of dementia was significantly higher in rural areas than in urban ones (6.05% vs. 4.40%, P < .001). The same regional difference was also seen for AD (4.25% vs. 2.44%, P < .001) but not for VaD (1.28% vs. 1.61%, P = .166). The difference in AD was not evident when the sample was stratified by educational level. Moreover, the risk factors for AD and VaD differed for urban and rural populations. A notably higher prevalence of dementia and AD was found in rural areas than in urban ones, and education might be an important reason for the urban-rural differences.
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Prevalence Studies of Dementia in Mainland China, Hong Kong and Taiwan: A Systematic Review and Meta-Analysis
Article
Full-text available
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. 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. 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.
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Prevalence of Dementia among Elderly People Living in Cotonou, an Urban Area of Benin (West Africa)
Article
Full-text available
  • Jun 2011
  • NEUROEPIDEMIOLOGY
Background/aims: The population of Benin is, like those of most developing countries, aging; dementia is therefore a major concern. Our goal was to estimate the prevalence of dementia in an elderly population living in urban Benin. Methods: In a cross-sectional community-based study, people aged 65 years and above were screened using the Community Screening Interview for Dementia and the Five-Word Test. Results: The prevalence of dementia was 3.7% (95% CI 2.6-4.8) overall. The figure increased with age and was higher among women than men. Conclusion: Dementia was slightly more prevalent than previously reported in a rural area of Benin, but the rate was similar to that recorded in other cities in developing countries.
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Prevalence of Dementia in Elderly Living in Two Cities of Central Africa: The EDAC Survey
Article
Full-text available
  • Oct 2010
  • DEMENT GERIATR COGN
Data on dementia from low- and middle-income countries are still necessary to quantify the burden of this condition. This multicenter cross-sectional study aimed at estimating the prevalence of dementia in 2 large cities of Central Africa. General population door-to-door surveys were conducted in the districts of Bangui (Republic of Central Africa) and Brazzaville (Congo) in elderly aged ≥ 65 years. The subjects were screened with the Community Screening Interview for Dementia and the Five-Words Test. Diagnosis of dementia was made according to the DSM-IV criteria and to the clinical criteria proposed by the NINCDS-ADRDA for Alzheimer's disease. We enrolled 496 subjects in Bangui and 520 in Brazzaville. The prevalence of dementia was estimated at 8.1% (95% CI = 5.8-10.8) in Bangui and 6.7% (95% CI = 4.7-9.2) in Brazzaville. The prevalence of dementia in urban areas of Central Africa is close to those observed in high-income countries.
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Prevalence of dementia and dementia subtypes among community-dwelling elderly people in Northern Nigeria
Article
Full-text available
  • Apr 2011
  • INT PSYCHOGERIATR
Dementia has important public health implications. The magnitude of the problem remains largely unknown in the developing countries. Three hundred and twenty-two community dwelling elderly persons and their caregivers in Zaria, Northern-Nigeria were enrolled in this study. They were interviewed using Community Screening Interview for Dementia (CSI-D), Consortium to Establish Registry for Alzheimer's disease (CERAD), Stick Design Test (SDT), Blessed Dementia Scale and a sociodemographic questionnaire. The data obtained were analyzed using the Statistical Package for Social Sciences version 15 for Windows. Diagnosis was based on fulfilling criteria for dementia in both the International Classification of Disease, 10th edition and the Diagnostic and Statistical Manual, 4th edition. The mean age of the subjects was 75.5 ± 9.4 years. The prevalence of dementia was 2.79% (CI 1-4.58%). Alzheimer's disease constituted 66.67% of all the cases of dementia in this community. Age was the only demographic factor associated with dementia. The prevalence rates of dementia and dementia subtypes in the developing countries are similar using standard diagnostic criteria and methods.
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Cognitive Impairment and Dementia in Elderly People Living in Rural Benin, West Africa
Article
Full-text available
  • Feb 2009
  • DEMENT GERIATR COGN
Dementia is increasing as a priority public health problem because of the ageing of the world population. Our goal was to estimate dementia and cognitive impairment prevalence in an elderly population of rural Benin. In a door-to-door survey, elderly people aged 65 years and above were screened using the Community Screening Interview for Dementia and the Five-Word Test. The prevalence of cognitive impairment was 10.4% and that of dementia was 2.6%. Age, current depressive disorder and absence of the APOE epsilon2 allele were significantly associated with cognitive impairment. Prevalence of dementia and cognitive impairment appears to be lower in this study than in developed countries.
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Epidemiology of Alzheimer’s disease and other forms of dementia in China, 1990–2010: A systematic review and analysis
Article
  • Jul 2013
Background: China is increasingly facing the challenge of control of the growing burden of non-communicable diseases. We assessed the epidemiology of Alzheimer's disease and other forms of dementia in China between 1990, and 2010, to improve estimates of the burden of disease, analyse time trends, and inform health policy decisions relevant to China's rapidly ageing population. Methods: In our systematic review we searched for reports of Alzheimer's disease or dementia in China, published in Chinese and English between 1990 and 2010. We searched China National Knowledge Infrastructure, Wanfang, and PubMed databases. Two investigators independently assessed case definitions of Alzheimer's disease and dementia: we excluded studies that did not use internationally accepted case definitions. We also excluded reviews and viewpoints, studies with no numerical estimates, and studies not done in mainland China. We used Poisson regression and UN demographic data to estimate the prevalence (in nine age groups), incidence, and standardised mortality ratio of dementia and its subtypes in China in 1990, 2000, and 2010. Findings: Our search returned 12,642 reports, of which 89 met the inclusion criteria (75 assessed prevalence, 13 incidence, and nine mortality). In total, the included studies had 340,247 participants, in which 6357 cases of Alzheimer's disease were recorded. 254,367 people were assessed for other forms of dementia, of whom 3543 had vascular dementia, frontotemporal dementia, or Lewy body dementia. In 1990 the prevalence of all forms of dementia was 1·8% (95% CI 0·0-44·4) at 65-69 years, and 42·1% (0·0-88·9) at age 95-99 years. In 2010 prevalence was 2·6% (0·0-28·2) at age 65-69 years and 60·5% (39·7-81·3) at age 95-99 years. The number of people with dementia in China was 3·68 million (95% CI 2·22-5·14) in 1990, 5·62 million (4·42-6·82) in 2000, and 9·19 million (5·92-12·48) in 2010. In the same period, the number of people with Alzheimer's disease was 1·93 million (1·15-2·71) in 1990, 3·71 million (2·84-4·58) people in 2000, and 5·69 million (3·85-7·53) in 2010. The incidence of dementia was 9·87 cases per 1000 person-years, that of Alzheimer's disease was 6·25 cases per 1000 person-years, that of vascular dementia was 2·42 cases per 1000 person-years, and that of other rare forms of dementia was 0·46 cases per 1000 person-years. We retrieved mortality data for 1032 people with dementia and 20,157 healthy controls, who were followed up for 3-7 years. The median standardised mortality ratio was 1·94:1 (IQR 1·74-2·45). Interpretation: Our analysis suggests that previous estimates of dementia burden, based on smaller datasets, might have underestimated the burden of dementia in China. The burden of dementia seems to be increasing faster than is generally assumed by the international health community. Rapid and effective government responses are needed to tackle dementia in low-income and middle-income countries. Funding: Nossal Institute of Global Health (University of Melbourne, Australia), the National 12th Five-Year Major Projects of China, National Health and Medical Research Council Australia-China Exchange Fellowship, Importation and Development of High-Calibre Talents Project of Beijing Municipal Institutions, and the Bill & Melinda Gates Foundation.
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The prevalence of dementia in rural Tanzania: A cross-sectional community-based study
Article
  • Jul 2013
  • INT J GERIATR PSYCH
Objectives: Despite the growing burden of dementia in low-income countries, there are few previous data on the prevalence of dementia in sub-Saharan Africa. The aim of this study was to estimate the prevalence of dementia in those who are 70 years and older in the rural Hai District of Tanzania. Methods: This was a two-phase cross-sectional survey. Using census data, we screened individuals aged 70 years and older from six rural villages using the Community Screening Instrument for Dementia in Phase I. In Phase II, a stratified sample of those identified in Phase I were clinically assessed using the DSM-IV criteria. Results: Of 1198 people who fulfilled the inclusion criteria, 184 screened positive for probable dementia, and 104 screened positive for possible dementia using the Community Screening Instrument for Dementia. During clinical assessment in Phase II, 78 cases of dementia were identified according to the DSM-IV criteria. The age-standardised prevalence of dementia was 6.4% (95% confidence interval: 4.9 to 7.9). Prevalence rates increased significantly with increasing age. Conclusions: The prevalence of dementia in this rural Tanzanian population is similar to that reported in high-income countries. Dementia is likely to become a significant health burden in this population as demographic transition continues. Further research on risk factors for dementia in sub-Saharan Africa is needed to inform policy makers and plan local health services.
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Prevalence of Alzheimer's Disease and Dementia in Two Communities: Nigerian Africans and African Americans
Article
  • Nov 1995
This article reports on a prevalence study of dementia and Alzheimer's disease among two groups of subjects with the same ethnic background but widely differing environments. The study was conducted among residents aged 65 years and older in two communities: Yorubas (N = 2,494) living in Ibadan, Nigeria, and African Americans (N = 2,212 in the community and N = 106 in nursing homes) living in Indianapolis, Indiana. The study design consisted of a screening stage followed by a clinical assessment stage for selected subjects on the basis of their performance on the screening tests. The age-adjusted prevalence rates of dementia (2.29%) and Alzheimer's disease (1.41%) in the Ibadan sample were significantly lower than those in the Indianapolis sample, both in the community-dwelling subjects alone (4.82% and 3.69%, respectively) and in the combined nursing home and community samples (8.24% and 6.24%, respectively). The prevalence rates of dementia and Alzheimer's disease increased consistently with advancing age in both study groups. To the authors' knowledge, this is the first study, using the same research method at the two sites, to report significant differences in rates of dementia and Alzheimer's disease in two different communities with similar ethnic origins.
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