. Finally, the World Health Organization recently declared dementia to be a public health priori which should be on the public health agenda of all countries. Although the large growth in the number of older adults in the coming decades will lead to an increase in dementia cases in countries around the world, a number of recent studies have suggested that the age-specific risk of dementia has actually decreased in high-income coun tries over the last 25 years, possibly due to increasing levels of education and more aggressive treatment of car diovascular risk factors that increase the risk of cognitive decline (for example, hypertension, hypercholesterolemia, and diabetes) [4]. However, it is unclear whether this opti- mistic trend in high-income countries will continue in the face of rising levels of obesity and diabetes, and it is also unclear whether there has been a similar or opposite trend in low- and middle-income countries [5,6]