The detailed estimates in this study constitute the best current basis for policymaking, planning, and allocation of health and welfare resources in dementia care. The age-specific prevalence of dementia varies little between world regions, and may converge further. Future projections of numbers of people with dementia may be modified substantially by preventive interventions (lowering incidence), improvements in treatment and care (prolonging survival), and disease-modifying interventions (preventing or slowing progression). All countries need to commission nationally representative surveys that are repeated regularly to monitor trends.

on Defeating Alzheimer's Disease and other dementias: a priority for European science and society Dementia includes a range of neurological disorders characterized by memory loss and cognitive impairment. The most common early symptom is difficulties remembering recent events. With the development of the disease, symptoms occur such as disorientation, mood swings, confusion, more serious memory loss, behavioural changes, difficulties in speaking and swallowing, as well as walking. Alzheimer Disease (AD) is the most common form of dementia (50-70% of dementia cases). Increasing age is the most important risk factor for AD.In 2012 and 2015, the World Health Organization (WHO) presented reports suggesting that Alzheimer Disease and other dementias (ADOD) should be regarded as a global public health priority 1,2 . Similar policy declarations have been presented by the European Union 3 , as well as by some individual countries. These policy declarations acknowledge trends that sometimes are described in terms of an epidemic or a "time-bomb". In 2015, the number of people affected by dementia worldwide is estimated to be almost 47 million and the numbers are expected to reach 75 million by 2030 and 131 million by 2050, with the greatest increase in low and middle income countries. The main reason for the increase is the global aging trend, since dementias are associated with a high age-specific prevalence, i.e., increasing prevalence with higher age. The global economic costs of dementia were estimated to be more than 600 billion USD in 2010 6 and 818 billion USD in 2015 5 . The direct costs in the medical and social care sectors, 487 billion USD, represent 0.65% of the aggregated global gross domestic products (GDP), which is an enormous economic impact of a single group of disorders, especially considering that 87% of the costs occur in high income countries. Care of people with dementia impacts several sectors in the society with the social care (long term care and home services) and informal care sectors constituting the greatest proportions -even greater than direct medical care 6 . In cost of illness studies, European cost estimates in 2010 ranged between 238,6 billion USD 6 and 105,6 billion € 7 .However, the economic and societal burden of ADOD corresponds to the aggregate burden of people with dementia and their next of kin. The progressive nature of dementia can influence the whole life situation for families over many years. So far, no cure or substantial symptom relieving treatment is available for ADOD. Thus, the impact of this terminal disease is already today enormous, and given the predictions for the future, ADOD represents an enormous challenge for any society, and particularly to the ageing European society.Further knowledge is needed regarding the causes of ADOD. A more complete understanding of the disease mechanisms is required for new diagnostic and therapeutic strategies. There is also a need to establish new cell-based and animal models representing, as far as possible, major clinical component...

Worldwide costs of dementia are enormous and distributed inequitably. There is considerable potential for cost increases in coming years as the diagnosis and treatment gap is reduced. There is also likely to be a trend in low- and middle-income countries for social care costs to shift from the informal to the formal sector, with important implications for future aggregated costs and the financing of long-term care. Only by investing now in research and the development of cost-effective approaches to early diagnosis and care can future societal costs be anticipated and managed.

Despite mortality due to communicable diseases, poverty, and human conflicts, dementia incidence is destined to increase in the developing world in tandem with the ageing population. Current data from developing countries suggest that age-adjusted dementia prevalence estimates in 65 year olds are high (≥5%) in certain Asian and Latin American countries, but consistently low (1-3%) in India and sub-Saharan Africa; Alzheimer's disease accounts for 60% whereas vascular dementia accounts for ∼30% of the prevalence. Early-onset familial forms of dementia with single-gene defects occur in Latin America, Asia, and Africa. Illiteracy remains a risk factor for dementia. The APOE ε4 allele does not influence dementia progression in sub-Saharan Africans. Vascular factors, such as hypertension and type 2 diabetes, are likely to increase the burden of dementia. Use of traditional diets and medicinal plant extracts might aid prevention and treatment. Dementia costs in developing countries are estimated to be US$73 billion yearly, but care demands social protection, which seems scarce in these regions.

Background Given the projected trends in population ageing and population growth, the number of people with dementia is expected to increase. In addition, strong evidence has emerged supporting the importance of potentially modifiable risk factors for dementia. Characterising the distribution and magnitude of anticipated growth is crucial for public health planning and resource prioritisation. This study aimed to improve on previous forecasts of dementia prevalence by producing country-level estimates and incorporating information on selected risk factors. MethodsWe forecasted the prevalence of dementia attributable to the three dementia risk factors included in the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 (high body-mass index, high fasting plasma glucose, and smoking) from 2019 to 2050, using relative risks and forecasted risk factor prevalence to predict GBD risk-attributable prevalence in 2050 globally and by world region and country. Using linear regression models with education included as an additional predictor, we then forecasted the prevalence of dementia not attributable to GBD risks. To assess the relative contribution of future trends in GBD risk factors, education, population growth, and population ageing, we did a decomposition analysis. FindingsWe estimated that the number of people with dementia would increase from 57•4 (95% uncertainty interval 50•4-65•1) million cases globally in 2019 to 152•8 (130•8-175•9) million cases in 2050. Despite large increases in the projected number of people living with dementia, age-standardised both-sex prevalence remained stable between 2019 and 2050 (global percentage change of 0•1% [-7•5 to 10•8]). We estimated that there were more women with dementia than men with dementia globally in 2019 (female-to-male ratio of 1•69 [1•64-1•73]), and we expect this pattern to continue to 2050 (female-to-male ratio of 1•67 [1•52-1•85]). There was geographical heterogeneity in the projected increases across countries and regions, with the smallest percentage changes in the number of projected dementia cases in high-income Asia Pacific (53% [41-67]) and western Europe (74% [58-90]), and the largest in north Africa and the Middle East (367% [329-403]) and eastern sub-Saharan Africa (357% [323-395]). Projected increases in cases could largely be attributed to population growth and population ageing, although their relative importance varied by world region, with population growth contributing most to the increases in sub-Saharan Africa and population ageing contributing most to the increases in east Asia. Interpretation Growth in the number of individuals living with dementia underscores the need for public health planning efforts and policy to address the needs of this group. Country-level estimates can be used to inform national planning efforts and decisions. Multifaceted approaches, including scaling up interventions to address modifiable risk factors and investing in research on biological mechanisms, will be key in addressing the expected incr...