multiple health conditions such as chronic physical diseases coexisting with mental or cognitive disorders, the effects of which may combine together in complex ways leading to disability and needs for care. However, studies from both high-income countries (6, 7) and low- and middleincome countries (8, 9) concur that, among older people, cognitive impairment and dementia make the largest contribution to needs for care, much more so than other types of impairment and other chronic diseases. THE GLOBAL ECONOMIC COST OF DEMENTIA The total estimated worldwide costs of dementia were US$ 604 billion in 2010, equivalent to 1% of the world’s gross domestic product (5). Low-income countries accounted for just under 1% of total worldwide costs (but 14% of the prevalence of dementia), middle-income countries for 10% of the costs (but 40% of the prevalence of dementia) and high-income countries for 89% of the costs (but 46% of the prevalence of dementia). About 70% of the global costs occurred in just two regions: Western Europe and North America. These discrepancies are accounted for by the much lower costs per person in lower income countries – US$ 868 in lowincome countries, US$ 3,109 in lower-middle-income, US$ 6,827 in upper-middle-income, and US$ 32,865 in high-income countries. The costs are driven mainly by social care needs; health care costs account for a small proportion of the total, given the low diagnosis rate, limited therapeutic options, and the underutilisation of existing evidence-based interventions (see Figure 2) (5). In all world regions, informal care provided by family, friends and the community is the cornerstone of the care system. In LAMIC these informal care costs predominate, accounting for 58% of all costs in low-income and 65% of all costs in middle-income countries, compared with 40% in high-income countries. Conversely, in high-income countries, the direct costs of social care (professional care in the community, and the costs of residential and nursing home care) account for the largest element of costs – 42%, compared with only 4% in LAMIC where such services are not generally available. In LAMIC, despite larger, extended families, the economic strain on family caregivers is substantial. Typically, around a fifth of caregivers have cut back on paid work, and paid care workers are becoming common in some cities, adding to the economic burden. Moreover, compensatory benefits are practically non-existent (3). Worldwide, the costs of dementia are set to soar. The World Alzheimer Report 2010 tentatively estimated an 85% increase in costs to 2030, based only on predicted increases in the numbers of people living with dementia. For several reasons, costs in LAMIC are likely to rise faster than in high-income countries. Wage levels are rising rapidly, and hence so is the opportunity cost or replacement cost of informal care. While currently very few people living with dementia in those regions live in care homes, this sector is expanding, particularly in urban settings in middle-income countries. This is boosted by demographic and social changes that reduce the availability of family members to provide care. References 1. Alzheimer's Disease International. Policy Brief for G8 Heads of Government. The Global Impact of Dementia 2013-2050. London: Alzheimer's Disease International; 2013. 2. World Health Organization. Dementia: A public health priority. Geneva: World Health Organization; 2012. 3. Alzheimer's Disease International. World Alzheimer Report 2009. London: Alzheimer's Disease International; 2009. 4. Norton S, Matthews FE, Barnes DE, Yaffe K, Brayne C. Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. Lancet Neurol. 2014 Aug;13:788-94. 5. Prince M, Prina M, Guerchet M.World Alzheimer Report 2013. Journey of Caring. An analysis of long-term care for dementia. London: Alzheimer's Disease International; 2013. 6. Wolff JL, Boult C, Boyd C, Anderson G. Newly reported chronic conditions and onset of functional dependency. JAGS. 2005 May; 53:851-5. 7. Aguero-Torres H, Thomas VS, Winblad B, Fratiglioni L. The impact of somatic and cognitive disorders on the functional