A new report on the global dimensions of Alzheimer’s disease says the overall shift toward older societies on the planet means that 9.9 million people will develop dementia every year, a faster pace than previously estimated.

Handout image: Tau lesions and senile plaques in Alzheimer’s disease. (Neuron, Maruyama et al.)

The World Alzheimer’s Report – which was compiled by Alzheimer’s Disease International, a U.K.-based federation of national Alzheimer’s associations – estimates that 46.8 million people worldwide have dementia. That number – which is larger than the population of Spain — will almost double every 20 years, reaching 131.5 million in 2050, the report says.

The latest report noted that the prevalence of Alzheimer’s cases has accelerated in East Asia and Africa compared with estimates six years ago, while the proportion of new and existing cases among populations in the Americas and Europe has fallen. The study’s authors, noting that advanced age is the single highest risk factor for Alzheimer’s, attribute the regional shift to the proportional growth of older populations in developing countries.

Fifty-eight percent of all people with dementia live in low- or middle-income countries, as defined by the World Bank, the report says. That number is expected to increase to 68 percent by 2050.

The projected costs for care of people with dementia will also grow. The report says the current cost tops $818 billion and is trending toward a trillion dollars by 2018.

“If global dementia were a country, it would be the 18th largest economy in the world,” the report says. Its authors used the latest data to urge national governments and the World Health Organization to step up research funding and the drive to reduce Alzheimer’s risks.

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In the United States, more than 5 million people are living with dementia, according to the Alzheimer’s Association.