The cause of most dementia is unknown, but the final stages of this disease usually means a loss of memory, reasoning, speech, and other cognitive functions. The risk of dementia increases sharply with age and, unless new strategies for prevention and management are developed, this syndromeis expected to place growing demands on health and long-term care providers as the world’s population ages. Dementia prevalence estimates vary considerably internationally, in part because diagnoses and reporting systems are not standardized. The disease is not easy to diagnose, especially in its early stages. The memory problems, misunderstandings, and behavior common in the early and intermediate stages are often attributed to normal effects of aging, accepted as personality traits, or simply ignored. Many cases remain undiagnosed even in the intermediate, more serious stages. A cross-national assessment conducted by the Organization for Economic Cooperation and Development (OECD) estimated that dementia affected about 10 million people in OECD member countries around 2000, just under 7 percent of people aged 65 or older.
Alzheimer’s disease (AD) is the most common form of dementia and accounted for between two-fifths and four-fifths of all dementia cases cited in the OECD report. More recent analyses have estimated the worldwide number of people living with AD/dementia at between 27 million and 36 million. The prevalence of AD and other dementias is very low at younger ages, then nearly
doubles with every five years of age after age 65. In the OECD review, for example, dementia affected fewer than 3 percent of those aged 65 to 69, but almost 30 percent of those aged 85 to 89. More than one-half of women aged 90 or older had dementia in France and Germany, as did about 40 percent in the United States, and just under 30 percent in Spain.
The projected costs of caring for the growing numbers of people with dementia are daunting. The 2010 World Alzheimer Report by Alzheimer’s Disease International estimates that the total worldwide cost of dementia exceeded US$600 billion in 2010, including informal care provided by family and others, social care provided by community care professionals, and direct costs of medical care. Family members often play a key caregiving role, especially in the initial stages of what is typically a slow decline. Ten years ago, U.S. researchers estimated that the annual cost of informal caregiving for dementia in the United States was US$18 billion.
The complexity of the disease and the wide variety of living arrangements can be difficult for people and families dealing with dementia, and countries must cope with the mounting financial and social impact. The challenge is even greater in the less developed world, where an estimated two-thirds or more of dementia sufferers live but where few coping resources are available. Projections by Alzheimer’s Disease International suggest that 115 million people worldwide will be living with AD/dementia in 2050, with a markedly increasing proportion of this total in less developed countries (Figure 9). Global efforts are underway to understand and find cures or ways of preventing such age-related diseases as Alzheimer’s.
Figure 9. The Growth of Numbers of People with Dementia in High- incomeCountries and Low- and Middle-income Countries: 2010-2050
Source: Alzheimer’s Disease International, World Alzheimer Report, 2010. Available at: http://www.alz.co.uk/research/files/WorldAlzheimerReport2010.pdf  (PDF, 1.3M).