MONDAY, Dec. 15, 2003 (HealthDayNews) -- Young adults who are genetically at risk for Alzheimer's disease may show signs of the disease years before the start of memory and thinking problems, a new study suggests.
"Patients with Alzheimer's disease have progressive reductions in brain glucose metabolism. This is an indicator of brain activity in certain parts of the brain," says lead researcher Dr. Eric M. Reiman, an associate head of psychiatry at the University of Arizona.
Reiman's research team has been investigating whether people with the apolipoprotein (APOE) episilon4 allele, a gene that is associated with an increased risk for Alzheimer's disease, show this reduction in glucose metabolism. Almost a quarter of the population carries this allele.
In earlier research, Reiman's group showed people with the APOE episilon4 allele, aged 50 to 65, had reductions in glucose metabolism.
In their current study, the researchers used magnetic resonance imaging (MRI) and positron emission tomography (PET) to measure brain structure and function in 12 APOE epsilon4 carriers and 15 non-carriers, aged 20 to 39.
The researchers found the patients with the APOE epsilon4 allele had abnormally low glucose metabolism in the same brain areas as patients with Alzheimer's disease. Their report appears in this week's issue of the Proceedings of the National Academy of Sciences.
"The earlier you can detect changes in the brain, the better the opportunity to intervene -- and the more likely that the treatment would have an effect before the brain is damaged by Alzheimer's," Reiman says.
Reiman notes that while there were decreases in glucose metabolism, not all patients with the APOE epsilon4 allele go on to develop Alzheimer's disease. However, "these early changes are surprising," he adds.
It is possible that decreased glucose metabolism is a very early sign of Alzheimer's disease and may provide a target for preventive treatment, Reiman says.
"I feel very confident that a prevention therapy of that kind is likely to emerge over time," Reiman says. "Even if that therapy was only modestly effective, it could have a tremendous public health impact."
According to Reiman, reduced glucose metabolism might be a cause of Alzheimer's disease or a result of other processes that cause the disease. "Either way, these changes provide a foothold for changes that result in brain pathology."
Reiman goes on to point out that reduced brain glucose metabolism is predictive of Alzheimer's disease, and as the disease progresses this reduction is even more pronounced. "So it is very relevant to the disease process," he adds.
At this time, Reiman does not recommend that healthy people be tested for the APOE epsilon4 allele or get a PET scan to predict their risk for developing Alzheimer's disease. "Neither test tells us with certainty whether someone will develop Alzheimer's disease, nor does it tell us what we might do about it," he says.
Dr. Mony J. de Leon, director of the Center for Brain Health at New York University School of Medicine, finds the results of Reiman's study intriguing.
However, whether these early brain abnormalities are predictive, or causal or related to Alzheimer's disease is not proven by this research, he says. "It's a good clue that something is going on, but not what it is," he adds.
"The findings are consistent with the belief of many Alzheimer's disease experts that Alzheimer changes begin in the brain many years before there are symptoms," says Dr. Stephen P. Salloway, an associate professor of clinical neurosciences at Brown University.
"If [these findings are] confirmed with larger trials, the combination of genetic and imaging techniques could identify people at risk for Alzheimer's disease long before symptoms emerge. These patients could be excellent candidates for future preventative treatments," he says.
And there's more new information about Alzheimer's disease. A study by two University of Florida researchers finds many people with Alzheimer's disease who wander off hide close to where they started.
"When people with Alzheimer's disease become lost in the community, the ones that are found dead have acted differently then the ones that are found alive," says Dr. Meredeth Rowe, an associate professor from the College of Nursing.
"The ones that are found dead seclude themselves, almost always in natural areas like woods and ditches and fields, and once they get into that area, they sit down or lie down and remain there until they die," she says.
Rowe and her colleague, Vicki Bennett, studied U.S. newspaper reports from 1998 to 2002 that described 93 incidents in which people with dementia died as a result of becoming lost. Their report appears in the November/December issue of the American Journal of Alzheimer's Disease and Other Dementias.
Rowe believes searches for missing Alzheimer patients need to focus within a mile of their home and be very thorough. "For some reason, when searchers are in the area where patients are hiding, they never respond to the searchers," she says.
Unless searchers come into direct contact with the person they can walk right by and never know the person was there, Rowe says. In one case, searchers looked for a missing man for eight days.
But with Rowe's help, the missing man was found alive in about an hour 300 yards from his home. "He was lying in a depression and had buried himself under some leaves, and a searcher literally tripped over him," Rowe says.
In urban areas, these missing people look for natural locals in which to hide, or hide in abandoned cars, or on rooftops and other places of concealment, she adds.
Rowe speculates that when these patients wander, they become confused. "Confusion creates fear and they hide, hoping that a parent will find them. So they just stay hidden until a parent comes and finds them," she says.
Most Alzheimer patients who wander off tend to wander in the area of their home and are quickly found, Rowe adds.
Dr. David Katz, an associate clinical professor of public health at Yale University, says "medicine is at its best when it is perfectly tailored to the needs of an individual patient, or a group of patients with very similar characteristics."
He adds that "to achieve such tailoring, keen observation and special attention to subtle patterns must inform medicine. The research reported here is testimony to the enduring value of keen observation, even in an age when technology permits us to peer into the deepest of mysteries."
"The lives of patients with dementia will doubtless be saved as a result of what is simply an astute observation of behavioral patterns," Katz says.
More information
To learn more about Alzheimer's disease, visit the National Institute on Aging or the Alzheimer's Association.
