More than 106 million people worldwide will develop Alzheimer’s disease by 2050—four times as many people as have the condition now, a new study says.

Currently, at least 26 million people suffer from the disease, characterized by progressive memory loss, language difficulties and eventually difficulty moving. The disease primarily affects people above the age of 65, so as life expectancies rise and people live longer, more are likely to develop the disease.

“We face a looming global epidemic of Alzheimer’s disease as the world’s population ages,” said lead author of the study, Ron Brookmeyer of Johns Hopkins University in Baltimore. “By 2050, one in 85 persons worldwide will have Alzheimer’s disease.”

The largest increase in the prevalence of Alzheimer’s will be in Asia—currently 48 percent of all cases are found there, but by 2050, it will have 59 percent of the world’s cases.

While the exact causes of Alzheimer’s disease remain elusive, there are several known risk factors:

Age: Simply put, the older you are, the more likely you are to develop Alzheimer’s.Genetics: Several gene mutations have been linked to an increased likelihood of developing the disease.Stroke/head injury: The death of brain cells caused by both of these can generate a key protein found in the plaques that cover the brains of Alzheimer’s patients.Physical fitness: A sedentary lifestyle, poor diet and cardiovascular problems have been linked to an increased chance of developing Alzheimer’s, though researchers are unsure exactly why this is.Mental fitness: Studies have linked “exercising” the mind (by doing crossword puzzles, for example) to a reduced risk of Alzheimer’s, though again, the mechanisms in play are unclear.Neuroticism: Some evidence shows that those easily overwhelmed by stress are at higher risk.Gender: Women are more likely to develop Alzheimer’s simply because they live longer than men.But a number of interventions, such as physical and mental exercise, show promise in delaying onset of the disease--even a delay of one year would reduce the number of expected cases in 2050 by 12 million, according to a model Brookmeyer created. Delaying both the onset and the progression would further reduce that number to 9.2 million cases.

“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,” Brookmeyer said.

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