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The Global Impact of Dementia: 2013-2050

  • French National Research Institute for Sustainable Development
Policy Brief for Heads of Government
The Global Impact of Dementia 2013–2050
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
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
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.
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
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.
Asia Pacific
Asia E
Asia S
Asia SE
Asia Central
Europe W
Europe Central
Europe E
America N
Latin America
N Africa/ Middle East
SSA Central
Standard Prevalence (%)
2010 2013 2030 2050
People with dementia (millions)
Figure 2 Increase in numbers of people with dementia worldwide (2010-2050), comparing original and
updated estimates
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%.
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
2013 2015 2020 2025 2030 2035 2040 2045 2050
Low and middle income countries
High income countries
Millions of people with dementia
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
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
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
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
Estimation of the number of people with
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
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.
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
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,
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.
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)
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
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
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Tel: +44 20 79810880
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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
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.
... The WHO reported that the top five causes of years of healthy life lost due to disability (YLD) among neurological disorders in highincome countries were Alzheimer's and other dementia, followed by cerebrovascular disease, neurological injuries, migraine, and neuropathies [4]. However, the rise in life expectancy and reduction in fertility resulted in a demographical shift from mainly youthful population into aging ones, triggering the increases in neurological disorders such as Alzheimer's, dementia, and Parkinson's disease [5][6][7]. ...
... To our knowledge, no studies have looked at the pattern of hospital admissions for all nervous system diseases across all age groups over the last 20 years. In 2010, there were approximately 135 million individuals worldwide suffering from dementia [6]. This number resulted in a huge economic impact which with an annual estimate of 600 billion USD [7]. ...
... This number resulted in a huge economic impact which with an annual estimate of 600 billion USD [7]. Since the prevalence of dementia progresses sharply at ages above 75, the projected increase in dementia cases by 2050 is three times the reported one [6,7]. As disorders of the nervous system, commonly reported as neurological disorders, are progressively identified as major causes of death and disability globally, this study aimed at providing a comprehensive analysis of the hospitalization pattern of such diseases during the period of 1999-2019 using publicly available data of England and Wales. ...
Full-text available
Objectives: This study aims to provide a comprehensive overview of the hospitalization pattern of nervous system diseases from 1999 to 2019. Methods: This is ecological research based on data from the Hospital Episode Statistics database in England and the Patient Episode Database in Wales, both of which are publicly available. Data on hospital admissions were collected between April 1999 and March 2019. Diagnostic codes (G00-G09: inflammatory diseases of the central nervous system, G10-G14: systemic atrophies primarily affecting the central nervous system, G20-G26: extrapyramidal and movement disorders, G30-G32: other degenerative diseases of the nervous system, G35-G37: demyelinating diseases of the central nervous system, G40-G47: episodic and paroxysmal disorders, G50-G59: nerve, nerve root and plexus disorders, G60-G65: polyneuropathies and other disorders of the peripheral nervous system, G70-G73: diseases of myoneural junction and muscle, G80-G83: cerebral palsy and other paralytic syndromes, and G89-G99: other disorders of the nervous system) from the tenth edition of the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) were used to identify hospital admissions. A Poisson model was used to examine the trend in hospital admissions. Results: During the study period, hospital admission rate increased by 73.5% (from 474.44 (95% CI 472.58-476.31) in 1999 to 823.37 (95% CI 821.07-825.66) in 2019 per 100,000 persons, trend test, p < 0.01). The most prevalent diseases of the nervous system hospital admissions causes were episodic and paroxysmal disorders, nerve, nerve root, and plexus disorders, and demyelinating diseases of the central nervous system which accounted for 37.4%, 22.1%, and 9.3%, respectively. Hospital admission rate between females increased by 79.1% (from 495.92 (95% CI 493.25-498.58) in 1999 to 888.33 (95% CI 884.97-891.68) in 2019 per 100,000 persons). Hospital admission rate between males was increased by 67.5% (from 451.88 (95% CI 449.28-454.49) in 1999 to 756.82 (95% CI 753.69-759.96) in 2019 per 100,000 persons). Conclusion: In the United Kingdom, hospital admissions for diseases of the nervous system are on the rise. Future research is needed to identify high-risk groups and suggest effective interventions to reduce the prevalence of these disorders.
... Amongst the most prevalent neurodegenerative diseases are Alzheimer's disease (AD) and Parkinson's disease (PD). AD is the most prevalent form of dementia worldwide, representing about 60-70% of all cases and is characterized by progressive cognitive impairment and memory loss (Prince et al., 2013). The two main AD hallmarks are the deposition of extracellular amyloid beta (Aβ) peptide into senile plates and the intracellular formation of neurofibrillary tangles as result of Tau hyperphosphorylation. ...
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Extracellular vesicles (EVs) are gaining increased importance in fundamental research as key players in disease pathogenic mechanisms, but also in translational and clinical research due to their value in biomarker discovery, either for diagnostics and/or therapeutics. In the first research scenario, the study of EVs isolated from neuronal models mimicking neurodegenerative diseases can open new avenues to better understand the pathological mechanisms underlying these conditions or to identify novel molecular targets for diagnosis and/or therapeutics. In the second research scenario, the easy availability of EVs in body fluids and the specificity of their cargo, which can reflect the cell of origin or disease profiles, turn these into attractive diagnostic tools. EVs with exosome‐like characteristics, circulating in the bloodstream and other peripheral biofluids, constitute a non‐invasive and rapid alternative to study several conditions, including brain‐related disorders. In both cases, several EVs isolation methods are already available, but each neuronal model or biofluid presents its own challenges. Herein, a literature overview on EVs isolation methodologies from distinct neuronal models (cellular culture and brain tissue) and body fluids (serum, plasma, cerebrospinal fluid, urine and saliva) was carried out. Focus was given to approaches employed in the context of Alzheimer’s and Parkinson’s diseases, and the main research findings discussed. The topics here revised will facilitate the choice of EVs isolation methodologies and potentially prompt new discoveries in EVs research and in the neurodegenerative diseases field.
... Over 55 million people currently live with dementia worldwide and this number is only growing at a staggering rate that is predicted to reach 78 million and 135 million people by 2030 and 2050, respectively [1,2]. Alzheimer's disease (AD) is the leading cause of dementia, contributing to 60-70% of cases and is the most common neurodegenerative disease. ...
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Tau pathology extends throughout the brain in a prion-like fashion through connected brain regions. However, the details of the underlying mechanisms are incompletely understood. The present study aims to examine the spreading of P301S aggregated tau, a mutation that is implicated in tauopathies, using organotypic slice cultures. Coronal hippocampal organotypic brain slices (170 µm) were prepared from postnatal (day 8–10) C57BL6 wild-type mice. Collagen hydrogels loaded with P301S aggregated tau were applied to slices and the spread of tau was assessed by immunohistochemistry after 8 weeks in culture. Collagen hydrogels prove to be an effective protein delivery system subject to natural degradation in 14 days and they release tau proteins up to 8 weeks. Slices with un- and hyperphosphorylated P301S aggregated tau demonstrate significant spreading to the ventral parts of the hippocampal slices compared to empty collagen hydrogels after 8 weeks. Moreover, the spread of P301S aggregated tau occurs in a time-dependent manner, which was interrupted when the neuroanatomical pathways are lesioned. We illustrate that the spreading of tau can be investigated in organotypic slice cultures using collagen hydrogels to achieve a localized application and slow release of tau proteins. P301S aggregated tau significantly spreads to the ventral areas of the slices, suggesting that the disease-relevant aggregated tau form possesses spreading potential. Thus, the results offer a novel experimental approach to investigate tau pathology.
... According to 2017 report by World Health Organization (WHO) indicate that by 2050, 150 million persons will be living with dementia; more than 68% of persons with dementia will reside in LMICs by 2050 (1)(2)(3). Worldwide, dementia is the fth leading cause of death and the second leading contributor to death from neurological diseases (4). Dementia care is expensive even in high income countries, according to recent estimate, > 818 billion USD is spent annually on dementiarelated care globally and by 2028 the worldwide cost of dementia care is estimated to be > 2 trillion USD (5). ...
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Background In 2050, it is estimated that the number of dementia patients in the sub Saharan Africa is expected to reach 5.05 million, an increase of 136% from the previous estimate of 2.14 million. The objectives of the present study were to assess the neuroimaging findings and associated factors in dementia suspected patients. Method A retrospective survey of the medical records of 121 suspected dementia patients whom presented to the Yehuleshet Specialty Clinic with subjective forgetfulness were reviewed. The study duration was between January 1, 2020 and December 31, 2021. Both descriptive and analytical statistics were used to analyze the data. Results The mean age was 70.4 (1SD = 10.3) years. Sixty four (52.9%) participants were age below 70. Male accounted for 57.9%. Hyperlipidemia was the commonest (38%) identified vascular risk factor followed by prevalence of hypertension (32.2%) and diabetes mellitus (22.3%). HIV infection was observed in 3.3%. Low mean serum vitamin D level (below 20ng/mL) was observed in individuals with focal & global cortical atrophy and those with white matter hyperintensity. Fifty two (43%) participants fulfilled the clinical and imaging criteria of vascular cognitive impairment (VCI). Nearly quarter of the patients had imaging evidences of focal or global cortical atrophy. Eleven (9.1%) had imaging evidences of surgical causes of dementia. the presences of comorbid hypertension, previous stroke, and Parkinsonism were independent predictors of vascular dementia. Conclusion The present study shows high burden of vascular cognitive impairment among individuals suspected of dementia. Furthermore, the presences of comorbid hypertension, previous stroke, and Parkinsonism were independent predictors of vascular dementia.
... Of those disorders, the global impact of neurocognitive disorders (NCDs) is also expected to escalate worldwide in parallel with longevity, from 44 million people in 2013 to 76 million in 2030 and 131 million by 2050 [7]. The socioeconomic impact of this trend is expected to be higher in low-and middle-income countries [8], and will have a total estimated cost of around 1 trillion US dollars by 2018 and 2 trillion by 2030 [9], with a mean cost per person of US $43,680 in G7 countries and US $20,187 in G20 countries [10].One of the most common NCDs is mild cognitive impairment (MCI) [11]. MCI is a syndrome defined as cognitive decline greater than that expected for an individual's age and education level but that does not interfere notably with activities of daily life, and may be indicative of Alzheimer's disease or another dementia [12]. ...
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Objective To investigate if there is epidemiological evidence of an association between edentulism and cognitive decline beside that currently available from limited sample-sized case series and cross-sectional studies considering limited co-variables. Materials and methods Data from two USA national health surveys [NHIS 2014–2017 and NHANES 2005–2018] were analyzed using multinomial logistic regression to study the impact of type of edentulism and number of remaining teeth on memory and concentration problems. Age, gender, socioeconomic status, education level, cardiovascular health index, body mass index, exercise, alcohol, smoking habits, and anxiety and depression were used as covariates. Results The combined population sample was 102,291 individuals. Age, socioeconomic status, educational level, anxiety and depression levels, and edentulism showed the highest odds ratios for cognitive decline. Number of teeth present in the mouth was found to be a predictor of cognitive status. This association showed a gradient effect, so that the lower the number of teeth, the greater the risk of exhibiting cognitive decline. Conclusions Edentulism was found among the higher ORs for cognitive impairment. Clinical relevance Maintenance of functional teeth through the promotion of oral health may contribute to the preservation of memory/concentration and other essential cognitive functions. Thus, increasing and efficiently coordinating efforts aimed at preventing of tooth loss in the adult population could substantially contribute to reduce the incidence of cognitive impairment.
... DPMs offer potential benefit in understanding and managing dementia. Alzheimer's Disease, the most common cause of dementia, is a global emergency: it affects over 46 million people in the world [51], causing a substantial socioeconomic burden. Moreover, causes and treatments are still not well understood. ...
Clinical decision-support tools (DSTs) represent a valuable resource in healthcare. However, lack of Human Factors considerations and early design research has often limited their successful adoption. To complement previous technically focused work, we studied adoption opportunities of a future DST built on a predictive model of Alzheimer’s Disease (AD) progression. Our aim is two-fold: exploring adoption opportunities for DSTs in AD clinical care, and testing a novel combination of methods to support this process. We focused on understanding current clinical needs and practices, and the potential for such a tool to be integrated into the setting, prior to its development. Our user-centred approach was based on field observations and semi-structured interviews, analysed through workflow analysis, user profiles, and a design-reality gap model. The first two are common practice, whilst the latter provided added value in highlighting specific adoption needs. We identified the likely early adopters of the tool as being both psychiatrists and neurologists based in research-oriented clinical settings. We defined ten key requirements for the translation and adoption of DSTs for AD around IT, user, and contextual factors. Future works can use and build on these requirements to stand a greater chance to get adopted in the clinical setting.
Dementia is a serious public health concern. It does not have any cure. Early detection of dementia is, thus, critical for effective symptom management as well as delaying cognitive and functional decline. This paper focuses on detecting onset of dementia using text and speech features provided by two publicly available datasets from the AAAI 2022 hackallenge. Our approach resulted in developing ACOUSTICS (AutomatiC classificatiOn of sUbjectS with demenTIa and healthy Controls using text transcriptions and Speech data)—an ensemble model with two deep learning-based architectures for text and speech analysis. ACOUSTICS achieved 89.8% accuracy when classifying individuals with dementia and health controls. Our approach outperforms current state-of-the-art methods in dementia detection.
Objective: We investigated the association between interval changes in physical activity (PA) and dementia risk among patients with new-onset type 2 diabetes. Research design and methods: We identified 133,751 participants newly diagnosed with type 2 diabetes in a health screening (2009-2012), with a follow-up health screening within 2 years (2010-2015). PA level changes were categorized into continuous lack of PA, decreaser, increaser, and continuous PA groups. Dementia was determined using dementia diagnosis codes and antidementia drug prescriptions. Results: During the median follow-up of 4.8 years, 3,240 new cases of all-cause dementia developed. Regular PA was associated with lower risks of all-cause dementia (adjusted hazard ratio [aHR] 0.82; 95% CI 0.75-0.90), Alzheimer disease (AD) (aHR 0.85; 95% CI 0.77-0.95), and vascular dementia (VaD) (aHR 0.78; 95% CI 0.61-0.99). Increasers who started to engage in regular PA had a lower risk of all-cause dementia (aHR 0.86; 95% CI 0.77-0.96). Moreover, the risk was further reduced among those with continuous regular PA: all-cause dementia (aHR 0.73; 95% CI 0.62-0.85), AD (aHR 0.74; 95% CI 0.62-0.88), and VaD (aHR 0.62; 95% CI 0.40-0.94). Consistent results were noted in various subgroup analyses. Conclusions: Regular PA was independently associated with lower risks of all-cause dementia, AD, and VaD among individuals with new-onset type 2 diabetes. Those with continuous regular PA and, to a lesser extent, those who started to engage in regular PA had a lower risk of dementia. Regular PA should be encouraged to prevent dementia in high-risk populations and those with new-onset type 2 diabetes.
Animal models have indicated that influenza vaccination may prevent or delay the onset of dementia. However, the epidemiological evidence in human beings is still limited. Given this background, this systematic review and meta-analysis aimed to summarize the current state of the art of observational studies investigating the association between influenza vaccination and the risk of dementia. We searched Scopus and Pubmed/Medline until 24 September 2021 for studies investigating influenza vaccination and the risk of dementia. After adjustment for potentially important confounding variables, data were reported as risk ratios (RRs) with 95% confidence intervals (CIs). Among 273 articles initially evaluated, five were included for a total of 292,157 older people free from dementia at baseline (mean age=75.5±7.4 years; 46.8% females). All studies were of high quality. Over a mean follow-up of 9 years, influenza vaccination mitigated the risk of dementia (RR=0.97; 95%CI: 0.94-1.00; I2=99%). This association held after adjustment for a mean of nine potential confounders (RR=0.71; 95%CI: 0.60-0.94; I2=95.9%). In sensitivity analysis, removing one study from the adjusted analyses, the adjusted RR remained similar (RR= 0.67; 95%CI: 0.63- 0.70), but the heterogeneity disappears (I2=0%). In conclusion, influenza vaccination was associated with a significantly lower risk of dementia suggesting that the vaccination of older people against influenza may also aid in the prevention of dementia.
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Little is known about multiple medicines and initial therapy among people with dementia. To examine the effect of multiple medicines on the initiation of anti-dementia therapy in patients diagnosed with cognitive impairment (CI), a retrospective study with 2742 CI patients was conducted based on the outpatients’ medical records. The dementias receiving 1–2 drugs were more likely to be prescribed with anti-dementia (one drug: OR = 1.877; two drugs: OR = 1.770) and psychotropic (one drug: OR = 1.980) treatment, whereas had lower chances of receiving psychotropic medication with the combinations of more than three drugs (Alzheimer’s disease: OR = .365; vascular dementia: OR = .940; frontotemporal lobe degeneration: OR = .957; and dementia with Lewy bodies/Parkinson’s disease dementia: OR = .952). Multiple medicines can affect anti-dementia therapy initiation in dementia patients and should be paid extreme caution.
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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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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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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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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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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.
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.
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.
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.
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.