Alzheimer's more common than previously thought
.
Alzheimer's Donation
Donate Online Now
.

The number of Americans with Alzheimer's disease is probably two to three times more than current estimates, according to a new study. And as the population ages, Alzheimer's could become the most expensive disease in the country.
In the new study, brain autopsies of elderly people who had had no symptoms of Alzheimer's showed that more than a third had lesions in their brains that met the criteria for the disease. The cost of caring for people with the brain disease tops $100 billion a year, according to the Lasker Foundation.
In the study at Rush University Medical Center in Chicago, the scientists performed autopsies on the brains of 134 people who had scored normally on a battery of memory and behavior tests. Of the 134 people, 50 showed lesions typical of Alzheimer's disease but had not had memory problems that indicated they had the disease.
The people with Alzheimer's pathology did have minor, but significant, lapses in certain memory tests, Bennett found. As a group, those people scored about a quarter point lower than people without Alzheimer's plaques. But the difference is not enough to make individual diagnoses. The people with undiagnosed lesions were also older on average (86 years old) when they died than the people who didn't meet the standard for the disease (81.7 years old).
That could mean that given a few more years of life, the people who didn't have the lesions might have developed them. None of the brains was completely free of changes, Bennett said.
"It's hard to find a brain without any pathology in it," he said.
The researchers at Rush are studying more than 2,000 older adults without dementia. The volunteers came from two study groups: Catholic nuns, priests and brothers participated in the Religious Orders Study, while the Rush Memory and Aging Project drew volunteers from the community around the university. They agreed to donate their brains to the research.
Elsewhere, researchers are among those hoping to find solutions for the memory-robbing disease.
The risk of developing Alzheimer's doubles every five years after age 65. Almost 40 percent of people over age 85 have the disease. But older people shouldn't panic if an acquaintance's name slips their minds or they have other common lapses.
"As long as people are able to carry out their normal daily activities, they shouldn't worry if they occasionally misplace their eyeglasses or car keys," Morris said. "If they put their keys in the freezer and can't find them then, well, that's a change (in behavior), and they should be evaluated."
The new study raises the possibility that people who have plaques in their brains but who haven't experienced a drop in their mental capacity, may have some protective factors that keep them from getting dementia.
Most treatments are based on reducing the amount of damage the disease causes in the brain, Bennett said. "But we're saying, let the pathology accumulate. Let's just adapt brains to handle it better," he said. Studies have previously shown that mental and physical exercise and social networking are helpful in reducing risk of the disease.
Waiting to start treatment until someone develops dementia is probably too late, Morris said. He called for new methods to detect brain lesions before people's memories lapse, and for treatments to stop the progression of the disease. Researchers are testing almost a dozen drugs against Alzheimer's in clinical trials.
About 99 percent of people who develop Alzheimer's have sporadic cases. That means they do not have specific mutations or known genetic factors that cause the disease. The problem could be that as people age, they make too much amyloid-beta, or that the ability to clear it from the brain slows down. The excess protein - as much as 1,000 times more than normal levels - could then congeal into plaques.
But no one has been able to measure the cycling of the protein in people's brains before. The test involves infusing a compound to label the newly produced amyloid-beta, and then sampling cerebral spinal fluid over 36 hours in the hospital.
The researchers have factored in hidden Alzheimer's disease and expect that up to a third of their seemingly healthy controls could have altered amyloid-beta metabolism, he said.