I'm Shep O'Neal with the VOA Special English Health Report.
Alzheimer's disease slowly destroys memory, thinking and reasoning skills.
The risk of developing this brain-wasting condition increases with age.
It is usually found in older people, but those with a family history may develop it earlier.
Alzheimer's is the most common form of dementia, a progressive loss of brain cells and mental abilities.
The Alzheimer's Association says the disease can last from three to twenty years, but the average person dies after eight years.
A new Swedish study estimated the direct costs of Alzheimer's disease and dementia care worldwide in two thousand three.
The estimate is one hundred fifty-six thousand million dollars.
That was based on an estimate that almost twenty-eight million people have dementia.
An estimated four and one-half million people have Alzheimer's disease in the United States.
As the population ages, the Alzheimer's Association says there may be as many as sixteen million cases by two thousand fifty.
Researchers suggest that healthy ways of living, started early, could reduce the risk of Alzheimer's or delay it.
Even good care of the teeth and gums could have an effect, because of a possible link between gum disease and higher risk of Alzheimer's.
Researchers say technologies such as PET scans and magnetic resonance imaging may be useful in discovering Alzheimer's early.
There are several drug treatments being developed.
A study reported last week involved some mice genetically engineered to develop dementia.
Researchers then shut off the genes that caused it.
The mice regained memory, as shown in their ability to guide their way around.
University of Minnesota researcher Karen Ashe says the results came as a surprise.
This VOA Special English Health Report was written by Cynthia Kirk.