THE EPIDEMIOLOGY AND IMPACT OF DEMENTIA CURRENT STATE AND FUTURE TRENDS 7.7 million new cases of dementia were anticipated each year, implying one new case every 4.1 seconds. This means that there were 3.6 million (46%) new cases per year in Asia, 2.3 million (31%) in Europe, 1.2 million (16%) in the Americas, and 0.5 million (7%) in Africa. Numbers of new cases increased and then declined with increasing age in each region; in Europe and the Americas peak incidence is among those aged 80-89 years, in Asia it is among those aged 75-84, and in Africa among those aged 70-79 (Table 1). For the year 2010, prevalence (35.6 million cases) is 4.6 times annual incidence, suggesting an approximate average survival from the onset of dementia till death of 4.6 years. + Low- and middle-income countries Latin America High-income countries Europe North America Incidence/1000 person-years Age group (years). Meta-analysed estimates of the incidence of dementia by world region/ development status (2) THE EPIDEMIOLOGY AND IMPACT OF DEMENTIA: CURRENT STATE AND FUTURE TRENDS http://www.who.int/mental_health/neurology/dementia/en/ WHO/MSD/MER/15.3 03 Informal care Direct social Lowincome countries Lower middleincome countries Upper middleincome countries Highincome countries FIGURE 2. Distribution of global societal costs of dementia, by country income status. FUTURE TRENDS IN THE PREVALENCE AND INCIDENCE OF DEMENTIA All current projections of the scale of the coming dementia epidemic assume that the age- and gender-specific prevalence of dementia will not vary over time, and that the increasing number of older people at risk drives the projected increases. However, the basis for this assumption is uncertain, since prevalence is a product of incidence and survival with dementia, and a fall in either or both of these indicators would lead to a fall in age-specific prevalence (3). A decline in age-specific incidence, at least in highincome countries, is theoretically possible, driven by changes in exposure to suspected developmental, lifestyle and cardiovascular risk factors for dementia. The strongest evidence for possible causal associations with dementia (plausible, consistent, strong associations, relatively free of bias and confounding) are those of low education in early life, hypertension in midlife, and smoking and diabetes across the life course. In a recent modelling exercise, it was concluded that a 10% reduction of key risk exposures would lead to an 8.3% reduction in the prevalence of dementia through to 2050, with a 15.3% reduction in prevalence of dementia anticipated assuming a 20% reduction in exposure prevalence (4). THE IMPACT OF DEMENTIA Dementia and cognitive impairment are the leading chronic disease contributors to disability, and, particularly, dependence among older people worldwide. While older people can often cope well, and remain reasonably independent even with marked physical disability, the onset of cognitive impairment quickly compromises their ability to carry out complex but essential tasks in daily life. In addition, people living with dementia will increasingly have difficulty to meet their basic personal care needs (5). The need for support from a caregiver often starts early in the dementia journey, intensifies as the illness progresses over time, and continues until death. There is a large literature attesting to the extent of the strain that caregivers experience, which is practical (hours spent caregiving detracting from other activities, particularly leisure and socializing), psychological (emotional strain, leading to a high prevalence of anxiety and depression), and economic (increased costs, coupled with giving up or cutting back on work to care) (5). THE EPIDEMIOLOGY AND IMPACT OF.3 04 Older people frequently have