Second study found that individuals who were informed about their risk weren't devastated
WEDNESDAY, July 15 (HealthDay News) -- Giving scientists insight into the origins of a devastating illness, new research suggests that people with a genetic propensity to develop Alzheimer's disease start experiencing memory loss as early as their 50s.
Unfortunately, scientists don't know of any way to prevent Alzheimer's. But an accompanying study finds that nearly everyone told of their high genetic risk of the disease was glad that they had been informed.
"In a small group, we didn't find a lot of harm done," said study author Dr. Robert Green, an Alzheimer's specialist. Even those who were told they have a 72 percent risk of developing the disease didn't tend to be devastated by the news, Green said.
Alzheimer's disease affects an estimated 5.3 million Americans, and the numbers are expected to grow as the population ages. There's no cure, although some treatments may reduce the severity of symptoms.
Scientists have known for some time that a genetic variation greatly boosts the risk of the disease, but it's still not clear how early the illness begins.
In one of the new studies, researchers looked at the genetic profiles of 815 volunteers aged 21 to 97.
Of those, 498 were at a normal genetic risk of developing Alzheimer's and 317 were at higher risk because of variations in a gene known as APOE. Of those in the latter group, 79 were at especially high risk.
The researchers gave cognitive tests to the volunteers over several years to see if there were any differences between the groups. The results appear in the July 16 issue of the New England Journal of Medicine.
The researchers found that those at higher risk of Alzheimer's began to score worse on the tests beginning in their mid-50s.
"Normally, your scores improve," explained study author Dr. Richard Caselli. "We saw that there was some improvement early on in their 40s and early 50s, but that beginning in their mid-50s we started to see changes. They weren't improving, but were beginning to decline over time."
Those at the highest risk were most likely to suffer a decline.
Brain scans have suggested that people doomed to get Alzheimer's begin to show signs of physical problems around age 60, said Caselli, clinical core director at the Arizona Alzheimer's Disease Center and chair of neurology at the Mayo Clinic.
"Until now, nobody has been able to show that there's actual cognitive changes that accompany this," Caselli said.
Still, the mental changes are small and may not even be noticeable. "These are normal, healthy working people," he said.
In the other study, researchers assigned 162 adults with a parent who had Alzheimer's to either receive or not receive information about their own genetic risk of the disease.
Contrary to some assumptions, those who learned about their risk understood the information they were given and were glad that they had been informed, said Green, co-director of the Alzheimer's Disease Clinical & Research Program at Boston University.
"Some people are information-seekers, and they just feel better and more complete when they have more information," Green said.
Get facts and figures about Alzheimer's from the Alzheimer's Association.
SOURCES: Robert Green, M.D., MPH, co-director, Alzheimer's Disease Clinical & Research Program, Boston University; Richard Caselli, M.D., clinical core director, Arizona Alzheimer's Disease Center, and chair, neurology, Mayo Clinic, Scottsdale; July 16, 2009, New England Journal of Medicine
All rights reserved