Epidemiology of dementia

doi:10.1016/j.mppsy.2007.10.001

Psychiatry

Volume 6, Issue 12, December 2007, Pages 488-490

https://doi.org/10.1016/j.mppsy.2007.10.001 Get rights and content

Abstract

Dementia is a syndrome characterized by a catastrophic, progressive global deterioration in intellectual function, and is one of the main causes of disability in late-life. Alzheimer’s disease (AD) is the commonest pathology, accounting for half to three-quarters of cases. Recent estimates suggest that 18–25 million people worldwide were affected in 2000, a figure that will double to 32–40 million by 2020. Dementia is largely a disease of older people – only 2% of those affected are under 65 years. After this, the prevalence doubles with every 5-year increment in age. This contribution looks at the prevalence and incidence of dementia worldwide, including in developing countries, and examines aspects of the aetiology and impact of the syndrome. Primary prevention and the provision of services are also discussed.

Section snippets

Prevalence

The most recent meta-analysis of European population-based studies, the EURODEM study carried out in the 1990s, used data from 11 studies in eight European countries.³ The overall pooled prevalence rates for men and women are shown in Table 1.

Subtypes

Studies in developed countries have consistently reported AD to be more prevalent than vascular dementia (VaD). Early studies in south-east Asian countries suggested that VaD was more prevalent than AD. However, AD has become nearly twice as prevalent as VaD in Korea, Japan, and China since demographic transition (i.e. decreased fertility rate together with increased longevity) in the early 1990s. Indian studies are contradictory, with both AD and VaD being more prevalent in different studies.

Incidence

The annual incidence rates reported in the EURODEM meta-analysis⁴ are roughly one-quarter of the point prevalence (Table 1), suggesting an average disease duration (from onset to death) of 4 years. Clinical studies have suggested a duration of 5–7 years from diagnosis. A recent meta-analysis⁵ of the age-specific incidence of all dementias was based on data from 23 published studies. The incidence of both dementia and AD rose exponentially up to 90 years, with no sign of levelling off. The

Dementia in developing countries

Demographic ageing proceeds apace in countries such as China, India and Latin America. In the 30 years up to 2020 the oldest sector of the population will have increased by 200% in developing countries, compared with 68% in the developed world.⁶ By 2020, two-thirds of all those over 60 (and presumably a similar proportion of all those with dementia) will be living in developing countries.¹ However, in the developing world there is more uncertainty about the frequency of dementia, with few

Trends in prevalence over time

Two population-based studies have continued to survey the residents of one area over a long period, and are therefore in the unusual position of being able to comment on the trends in prevalence over time.

•
The Lundby study in Sweden⁸ indicated no significant change in the prevalence or incidence of either multi-infarct dementia or what was described at the time as ‘senile dementia’ during the period from 1947 to 1972.
•
In Rochester, Minnesota, USA, the meticulously maintained health-care register

Aetiology

The rare early-onset form of AD is highly heritable, and single-gene mutations at one of three loci (β-amyloid precursor protein, presenilin-1 and presenilin-2) account for the majority of cases. Late-onset AD is a multifactorial disorder. The apolipoprotein E (ApoE) gene polymorphisms account for up to 50% of the population attributable fraction, the ε4 allele being enriched among AD cases. However, low concordance rates among monozygotic twins suggest a substantial environmental influence.

Impact

Dementia is one of the main causes of disability in late-life. The consensus-estimated disability weight for dementia applied in the Global Burden of Disease Report⁶ was higher than that for almost any other condition with the exception of spinal cord injury and terminal cancer. Among older people, dementia was the most burdensome neuropsychiatric disorder, accounting for more than half of all disability-adjusted life years (DALYs) in this domain of morbidity.⁶

People with dementia are heavy

Prevention and care

Primary prevention should focus on risk factors for vascular disease, including:

•
hypertension
•
smoking
•
type 2 diabetes mellitus
•
hyperlipidaemia.

The epidemic of smoking in developing countries and the rising prevalence of type 2 diabetes in Asia are particular causes of concern. More work is needed to identify further modifiable risk factors.

Achieving progress with dementia care depends on creating the climate for change. Lack of awareness, which is widespread among policy-makers, clinicians and the

References (18)

A. Hofman et al.
Atherosclerosis, apolipoprotein E, and prevalence of dementia and Alzheimer’s disease in the Rotterdam Study
Lancet
(1997)
I. Skoog et al.
15-year longitudinal study of blood pressure and dementia
Lancet
(1996)
M.J. Prince
The need for research on dementia in developing countries
Trop Med Int Health
(1997)
A. Wimo et al.
The magnitude of dementia occurrence in the world
Alz Dis Assoc Disord
(2003)
A. Lobo et al.
Prevalence of dementia and major subtypes in Europe: a collaborative study of population-based cohorts. Neurologic Diseases in the Elderly Research Group
Neurology
(2000)
L. Fratiglioni et al.
Incidence of dementia and major subtypes in Europe: a collaborative study of population-based cohorts. Neurologic Diseases in the Elderly Research Group
Neurology
(2000)
Jorm, Jolley...
C.J.L. Murray et al.
The global burden of disease and injury series, Volume 1. A comprehensive assessment of mortality and disability from diseases, injuries and risk factors in 1990 and projected to 2020
(1996)
M. Prince
Methodological issues in population-based research into dementia in developing countries. A position paper from the 10/66 Dementia Research Group
Int J Geriatr Psychiatry
(2000)

There are more references available in the full text version of this article.

Cited by (18)

Neurologic dysphagia
2018, Dysphagia Evaluation and Management in Otolaryngology
The neurologic basis of swallowing is supremely important, which includes neuromuscular control, sensory feedback, and brainstem coordination and influence. Thus, the many potential defects often seen in neurodegenerative disease, stroke, and dementia can have a profound impact on safe swallowing. Since neurologic dysphagia is most commonly seen in the elderly, other comorbid conditions can have a synergistic effect on aspiration risk, including deconditioning, oropharyngeal muscular atrophy, impaired cognition, and medication-related sicca. We review features of these diseases, and advise on approaches to screening, evaluation, intervention, and recognizing sentinel indicators of decline which increase aspiration risk.
Dysphagia in Stroke, Neurodegenerative Disease, and Advanced Dementia
2013, Otolaryngologic Clinics of North America
Citation Excerpt :
In 2001 there were 24.3 million people in the world with dementia, whereas in 2040 the number is estimated to increase to more than 81 million. The prevalence of dementia is estimated to double every 5 years after 65 years of age, and at age 85 years the prevalence is approximately 50%.29 Dementia is a leading cause of death in the United States, with mortality affected by aspiration, hydration, and nutritional status.
High cortisol levels are associated with cognitive impairment no-dementia (CIND) and dementia
2013, Clinica Chimica Acta
Citation Excerpt :
We observed older individuals in CIND and dementia groups when compared to control, even if classifying participants with ≤ 79 y. This finding was expected, since there is a strong correlation between age and dementia [31,34]. Nitrini et al. [35] reviewed the prevalence of dementia in Latin-America studies and found the following rates according to age group: 2.4% (65–69 y), 7.0% (75–79 y) and 20.2% (85–89 y).
This study aimed to compare serum cortisol concentrations in cognitively healthy elderly and in subjects with cognitive impairment no dementia (CIND) and dementia, besides to evaluate these concentrations according to apolipoprotein E genotype (APOE).
Three-hundred and nine elderly enrolled in the Pietà Study (Brazil) were divided in 3 groups: control (n = 158), CIND (n = 92) and dementia (n = 59) and had concentrations of morning serum cortisol measured. Hormone concentrations were measured by chemiluminescence and APOE genotypes were determined by PCR followed by restriction fragment length polymorphism (RFLP).
Medians of cortisol concentrations (μg/dl) for the groups were 12.14 (interquartile range — IQR 6.34) for control, 13.65 (IQR 5.88) for CIND and 14.47 (IQR 7.35) for dementia. Significant differences were observed for control vs. CIND (P = 0.003), control vs. dementia (P = 0.001), but not for CIND vs. dementia (P = 0.269). No association was observed between cortisol concentrations and APOE genotype among the groups (P = 0.348).
The elevation in cortisol concentrations is associated with dementia, independently of APOE genotypes. Further studies are required to understand if elevation of cortisol is an initial event and how hippocampal damage and the loss of hypothalamus–pituitary–adrenal (HPA) axis inhibition may affect its concentrations.
Alzheimer's disease and anaesthesia: Potential relationships and clinical implications
2011, Annales Francaises d'Anesthesie et de Reanimation
La maladie d’Alzheimer est une pathologie cérébrale dégénérative majeure par sa fréquence et son retentissement en matière de santé publique. Son origine reste encore insuffisamment comprise. Si l’implication de facteurs environnementaux, dont l’exposition aux agents anesthésiques, reste discutée, la période périopératoire est source de nombreux éléments potentiellement délétères, en particulier chez les sujets âgés souvent déjà fragilisés. Des études cliniques évaluant au mieux l’impact de cette période périopératoire restent nécessaires afin de définir des stratégies de prise en charge optimisées avec une adaptation spécifique des traitements et des techniques anesthésiques. Dans cette attente, l’information du patient et de son entourage ainsi que l’attention portée à la sphère cognitive doit se renforcer, en particulier chez les patients à risque de décompensation cognitive.
Alzheimer's disease is the most common form of dementia. As the aging population increases, Alzheimer's disease is becoming a major concern of Public Health. Many molecular lesions have been detected in Alzheimer's disease, but physiopathology is still poorly understood. If the neurotoxicity of anaesthetics in human remains debatable, perioperative period is certainly a high-risk factor for cognitive impairment, especially in elderly population. Large clinical studies are required to develop new strategies for perioperative management in such patients, including the adjustment of anaesthesia techniques. Before that, information of patient and its relatives and a particular attention for elderly during anaesthesia and perioperative period should be considered.
Fall determinants in older long-term care residents with dementia: A systematic review
2013, International Psychogeriatrics
Trace element analysis of hairs in patients with dementia
2010, Journal of Synchrotron Radiation

View all citing articles on Scopus

View full text

Epidemiology of dementiaEpidemiology of dementia

Abstract

Section snippets

Prevalence

Subtypes

Incidence

Dementia in developing countries

Trends in prevalence over time

Aetiology

Impact

Prevention and care

Lancet

Lancet

The need for research on dementia in developing countries

Trop Med Int Health

The magnitude of dementia occurrence in the world

Alz Dis Assoc Disord

Prevalence of dementia and major subtypes in Europe: a collaborative study of population-based cohorts. Neurologic Diseases in the Elderly Research Group

Neurology

Incidence of dementia and major subtypes in Europe: a collaborative study of population-based cohorts. Neurologic Diseases in the Elderly Research Group

Neurology

The global burden of disease and injury series, Volume 1. A comprehensive assessment of mortality and disability from diseases, injuries and risk factors in 1990 and projected to 2020

Methodological issues in population-based research into dementia in developing countries. A position paper from the 10/66 Dementia Research Group

Int J Geriatr Psychiatry

Epidemiology of dementia
Epidemiology of dementia