LAUSR

By far the most important risk factor for the development of dementia is age itself, with the risk of dementia doubling every 5 years, extending into the ninth decade of life.1 Until recently, dementia was thought to be predominantly a problem of more developed countries because of their greater proportion of older people. Many European and Scandinavian countries have already experienced considerable population aging because of increased longevity and falling fertility rates. For example, in 2016 in the United Kingdom, 18% were over the age of 65 years and 2.4% over the age of 85 years. In contrast, in other developed countries, such as the United States of America, Australia, New Zealand, and Canada, population aging is not as pronounced, mainly because of the large migration intakes that have distorted age structures by bringing younger people into their communities and increasing fertility rates. In Australia in 2016, 15% of the population was aged over 65 years and 2.0% over the age of 85 years. In these relatively young developed countries, population aging will be more dramatic as proportionate migration intakes decrease, such that by 2050 Australia will have a population of 6% aged over 85 years. However, the situation is more complex and uneven in other parts of the world, where ageing has occurred over 2 generations rather than 2 centuries. The number of people with dementia worldwide in 2015 was just under 50 million, with two-thirds of all cases living in lowand middle-income countries.2 Countries such as South Korea have experienced very rapid aging, with 9% over the age of 65 years in 2004, rising to 13% in 2015. China still has relatively low numbers of older people, but falling fertility rates and increased longevity have increased the number of people over the age of 65 years from 4% in 1960 to 10% in 2016; 25% are expected to be over the age of 65 years by 2050.3 Already there are over 9million peoplewith dementia in China, and this is dramatically increasing. It is important to emphasize that it is the population in advanced years that drive the numbers of people with dementia because of the exponential increased prevalence with age. Of concern is the observation that in lowand middle-income