Global Prevalence of Dementia: A Delphi Consensus Study

Department of Public Health and Primary Care, University of Cambridge, Cambridge, England, United Kingdom
The Lancet (Impact Factor: 45.22). 01/2006; 366(9503):2112-7. DOI: 10.1016/S0140-6736(05)67889-0
Source: PubMed


100 years after the first description, Alzheimer's disease is one of the most disabling and burdensome health conditions worldwide. We used the Delphi consensus method to determine dementia prevalence for each world region.
12 international experts were provided with a systematic review of published studies on dementia and were asked to provide prevalence estimates for every WHO world region, for men and women combined, in 5-year age bands from 60 to 84 years, and for those aged 85 years and older. UN population estimates and projections were used to estimate numbers of people with dementia in 2001, 2020, and 2040. We estimated incidence rates from prevalence, remission, and mortality.
Evidence from well-planned, representative epidemiological surveys is scarce in many regions. We estimate that 24.3 million people have dementia today, with 4.6 million new cases of dementia every year (one new case every 7 seconds). The number of people affected will double every 20 years to 81.1 million by 2040. Most people with dementia live in developing countries (60% in 2001, rising to 71% by 2040). Rates of increase are not uniform; numbers in developed countries are forecast to increase by 100% between 2001 and 2040, but by more than 300% in India, China, and their south Asian and western Pacific neighbours.
We believe that the detailed estimates in this paper constitute the best currently available basis for policymaking, planning, and allocation of health and welfare resources.

Download full-text


Available from: Carol Brayne
    • "One critical limitation of previous studies of aging effects on RSFC is that few used a combination of neuropsychological assessment and structured psychiatric interviews to identify undiagnosed psychiatric conditions or mild cognitive impairment. This is clearly relevant because cognitive and psychiatric disorders are highly prevalent in the general population (Ferri et al. 2005; Steel et al. 2014) and are associated with abnormalities in RSFC (Greicius 2008; Seeley et al. 2009). Accordingly, we used a careful and active investigation to select a sample free of cognitive deficits and lifetime psychiatric disorders. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Aging is associated with decreased resting-state functional connectivity (RSFC) within the default mode network (DMN), but most functional imaging studies have restricted the analysis to specific brain regions or networks, a strategy not appropriate to describe system-wide changes. Moreover, few investigations have employed operational psychiatric interviewing procedures to select participants; this is an important limitation since mental disorders are prevalent and underdiagnosed and can be associated with RSFC abnormalities. In this study, resting-state fMRI was acquired from 59 adults free of cognitive and psychiatric disorders according to standardized criteria and based on extensive neuropsychological and clinical assessments. We tested for associations between age and whole-brain RSFC using Partial Least Squares, a multivariate technique. We found that normal aging is not only characterized by decreased RSFC within the DMN but also by ubiquitous increases in internetwork positive correlations and focal internetwork losses of anticorrelations (involving mainly connections between the DMN and the attentional networks). Our results reinforce the notion that the aging brain undergoes a dedifferentiation processes with loss of functional diversity. These findings advance the characterization of healthy aging effects on RSFC and highlight the importance of adopting a broad, system-wide perspective to analyze brain connectivity. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail:
    No preview · Article · Aug 2015 · Cerebral Cortex
    • "Ageing is a problem faced by many countries and with this, comes the attendant problem of dementia. With increased life expectancy, the number of individuals with dementia is expected to rise rapidly (Ferri et al., 2005; Luengo-Fernandez, Leal, & Gray, 2010) and bringing in its wake a range of social, economic and public health challenges. Through a combination of advice, treatment and support, the person with dementia and their family can be enabled and empowered which in turn can reduce crises and delay institutionalization (Prince, Bryce, & Ferri, 2011). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Objectives: Dementia is inevitably associated with an ageing population which has tremendous public health, social and economic implications. Yet the extant evidence suggests that the diagnosis of dementia in general is neither timely nor accurate. The aim of this present study was to establish the prevalence of dementia as diagnosed by medical practitioners in Singapore and its associated factors. Method: The analysis is based on a national epidemiological study of older adults in Singapore which had established the prevalence of dementia using the 10/66 protocol. It was a community based survey, and face-to-face interviews were conducted with 2565 respondents (a response rate of 66%) and 2421 informants. Results: In all, 3% of the respondents were diagnosed by a medical practitioner to have dementia of which 11.5% were diagnosed by general practitioners. Only 30.3% were prescribed medications specifically for dementia. Those with comorbid depression were more likely to be diagnosed to have dementia. Conclusion: The apparent low rate of diagnosis by medical practitioners is in line with studies done in the West. There is a need to elucidate the reasons underlying this under-diagnosis in order to better address this gap.
    No preview · Article · Aug 2015 · Aging and Mental Health
  • Source
    • "AD happens in 3-5% of individuals aged more than 65 years old (McCullagh et al. 2001). Every year 4.6 million cases of AD are reported, and it has been suggested that the number of patients will double every 20 years to affect 80 million people by 2040 (Ferri et al. 2005). AD is characterised by premature severe atrophy of the cerebral cortex frontal, temporal, occipital and parietal lobes due to excessive neuronal cell death (Dickerson et al. 2009). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Diseases involving the nervous system drastically change lives of victims and commonly increase dependency on others. This paper focuses on senile dementia from both the neuroscientific and Islamic perspectives, with special emphasis on the integration of ideas between the two different disciplines. This would enable effective implementation of strategies to address issues involving this disease across different cultures, especially among the world-wide Muslim communities. In addition, certain incongruence ideas on similar issues can be understood better. The former perspective is molded according to conventional modern science, while the latter on the analysis of various texts including the holy Qur'an, sunnah [sayings and actions of the Islamic prophet, Muhammad (pbuh)] and writings of Islamic scholars. Emphasis is particularly given on causes, symptoms, treatments and prevention of dementia.
    Full-text · Article · Jul 2015 · Journal of Religion and Health
Show more