Alzheimer's more widespread than commonly believed?

Study examines pathology

A STUDY PRESENTED AT THE RECENT World Alzheimer Congress 2000 in Washington DC refuted the current estimates in the literature that put the number of people in the United States with Alzheimer's disease at about 4 million, suggesting that the actual number is much larger.

Researchers examined the rate of change in memory function over six years in about 750 nuns, priests, and brothers participating in the Religious Orders Study, a longitudinal, clinical-pathologic study of aging and Alzheimer's disease. Moreover, study author David Bennett, MD, director of Rush Alzheimer's Research Center at Rush-Presbyterian-St. Luke's Medical Center in Chicago, measured the amount of Alzheimer's disease pathology in the first 100 participants who had a brain autopsy.

Bennett and colleagues believe that people with mild cognitive impairment declined much faster on memory tests than people with no cognitive impairment. Further, Alzheimer's disease pathology already was present to a large degree in people who died with mild cognitive impairment.

Researchers also examined the relation of Alzheimer's disease pathology to memory function just prior to death and to rates of change in memory several years prior to death. They found Alzheimer's disease pathology related to both. Overall, the data suggest that many people with mild memory problems who do not meet conventional criteria for dementia are exhibiting the pathology of Alzheimer's disease.

"Often these people are not diagnosed with Alzheimer's or told that their mild memory loss is part of normal aging," he says. He continues that this research indicates the magnitude of the public health problem posed by Alzheimer's may be even larger than commonly recognized, and that increased funding for clinical care and research is needed to effectively combat this disease.

Mental stress test for Alzheimer's

In other news, another study suggests that the brains of people with a genetic risk for Alzheimer's have to work harder than normal to perform simple memory tasks long before any outward symptoms of the disease develop.

The findings suggest that the measuring technique used in the study could develop into a form of mental stress test for early detection of Alzheimer's.

Zaven Khachaturian, former director of the Alzheimer's Research Office at the National Institutes of Health, said in a published report that the study is exciting because it bolsters hope of identifying patients who could benefit from early drug treatment.

"There's something wrong already, but you can't see it clinically," he said.

The study was conducted by scientists at the University of California at Los Angeles (UCLA) and was published in a recent New England Journal of Medicine. Thirty people ages 47 to 82, all of whom bad tested normal on conventional memory tests, were recruited.

They were checked for ApoE E4 allele, a gene variant already known to be associated with Alzheimer's. In fact, UCLA psychiatrist Gary Small, PhD, was part of a research team that discovered the first major genetic risk factor for Alzheimer's in 1993. He and his team found that people who inherit a certain version of the gene called apolipoprotein-E (ApoE) are at significantly increased risk for developing the disease. The ApoE gene is the blueprint for a protein that helps deliver cholesterol, a critical building block of the membranes of newly forming cells. Then, their brains were scanned with magnetic resonance imaging while they recalled words memorized from a list.

Those with the Alzheimer's gene produced scan signals that were about twice as strong and more widespread than those without the gene. The magnetic signals indicate greater blood flow--and thus greater mental effort--in regions of the brain near the temple and forehead, the researchers say. Earlier research had implicated those areas in Alzheimer's.

In recent years, researchers have pinpointed metabolic brain deficiencies and other early markers that may foretell Alzheimer's. This study, though, is the first time researchers have identified brain differences in at-risk people while they perform assigned mental tasks.

"The brains appeared to be compensating. The brains of people with the genetic risk have to work harder," Small, who led the research, reportedly said.

Supercomputer used in Alzheimers research

Alzheimer's researchers at Boston University arc getting high-tech help. With the help of IBM, BU has become the first academic research center to implement IBM's ASCI White, the world's most powerful supercomputer. The computer, which fills the space of two basketball courts, will be put to many uses, one of which is to analyze the formation of senile plaques in the brains of patients with Alzheimer's disease.