The number of those hit by the debilitating Alzheimer's across the globe would quadruple by 2050, and the biggest jump is projected for Asia. At the moment the continent has almost half of today's Alzheimer's patients, at 12.6 million.
By 2050, the region will have 62.8 million of the world's 106 million Alzheimer's, researchers at Johns Hopkins University say.
When the world's Alzheiemer population explodes, from 26 million now, one in 85 people will have the brain-destroying disease, it is pointed out.
The new estimates, being presented Sunday at an Alzheimer's Association conference in Washington, are not very different from previous projections of the looming global dementia epidemic with the graying of the world's population.
But they serve as a sobering reminder of the toll to come if scientists cannot find better ways to battle Alzheimer's and protect aging brains.
"If we can make even modest advances in preventing Alzheimer's disease, or delay its progression, we could have a huge global public health impact," said Johns Hopkins public health specialist Ron Brookmeyer, who led the new study.
A recent U.S. study estimated that this nation's Alzheimer's toll will reach 16 million by 2050, compared with more than 5 million today. The new estimate is significantly lower, suggesting only 3.1 million North American cases today and 8.8 million by 2050.
Among the estimates for other regions are:
· Africa, 1.3 million today and 6.3 million in 2050.
· Europe, 7.2 million and 16.5 million.
· Latin America and the Caribbean, 2 million and 10.8 million.
· Oceania (Australia, New Zealand, New Guinea, and various islands of the Malay Archipelago) 200,00 and 800,000.
Meantime researchers say that they have discovered a new gene linked with late-onset Alzheimer's disease.
People with a damaged copy of the gene, GAB2, may be at four times increased risk of developing dementia, Neuron journal reports.
Experts said the latest findings were some of the most significant to emerge since the discovery of the ApoE4 Alzheimer's gene.
Late-onset Alzheimer's affects one in 10 people over 65 and half of over 85s.
The researchers, from 15 institutions including the Institute of Neurology in London, analysed the DNA of 1,411 people and found GAB2 influenced the risk of dementia among those with APOE4.
GAB2 appears to modify the effects of this better known Alzheimer's gene.
In turn, this leads to the formation of the characteristic protein "tangles" found in the brains of people with Alzheimer's, the researchers told Neuron.
Professor Clive Ballard, director research at the Alzheimer's Society, said: "This impressive research suggests a common gene could be responsible for a four-fold increased risk of developing Alzheimer's disease.
"It is the most important risk factor gene to be identified in relation to tangles, which develop in the brain in Alzheimer's disease."