BOSTON, Dec. 20 (UPI) -- Researchers said Wednesday they have developed a new molecule that makes it possible for scientists to look inside the brain and distinguish between people who are normal, who have mild forms of dementia or who have Alzheimer's disease.
The molecule, called FDDNP by the University of California-Los Angeles researchers who developed it, was specifically designed to attach to "tau tangles" and amyloid protein in the brain. Accumulations of tau and amyloid are hallmarks of Alzheimer's disease.
When the molecule is injected intravenously into the bloodstream, positron-emission tomography (PET) scanning creates an image of the brain that is highlighted by accumulations of FDDNP, the researchers report in Thursday's editions of the New England Journal of Medicine.
"FDDNP-PET scanning can differentiate persons with mild cognitive impairment from those with Alzheimer's disease and those with no cognitive impairment," said Gary Small, professor of medicine and director of the UCLA Center on Aging.
Small, who developed the molecules and owns patents and receives royalties from a licensing agreement with Siemens, recruited 83 patients for studies with the new scanning agent. The 83 patients were selected from an initial group of 575 individuals who were at one time willing to be included in the clinical trial of the device.
In the article in the journal, Small shows illustrations that depict differences in how areas of the brain that contain FDDNP "light up" under the PET scan. Few highlights are visible among the control patients. Larger areas of highlighted brain area are seen in the scans of the mildly impaired individuals. Almost all the brain is involved in patients judged to have Alzheimer's disease.
Mild cognitive impairment is a condition in which individuals have memory and/or thinking problems that can be measured on tests but are not severe enough to interfere with their daily activities. In some cases, patients with mild cognitive impairment go on to develop Alzheimer's disease -- a progressive illness that destroys a person's memory and eventually the ability to perform activities of daily living.
Small also tested other imaging modalities, such as magnetic resonance imaging and other PET imaging agents, but FDDNP-PET was significantly better in showing differentiation among the volunteers in the study.
"At this point, we would consider FDDNP as just a research tool," said Susan Molchan, program director for biomarkers, diagnosis and neuroimaging for Alzheimer's disease at the National Institute of Aging in Bethesda, Md.
"It's going to take a lot more people to be scanned with this molecule for it to be useful in diagnosis," Molchan told United Press International.
She said that, for the near future, the major role of FDDNP might be helping determining which new pharmaceutical products are actually reaching their target in the brain, and if they indeed are able to halt progression or regress tau and amyloid deposits.
"Both Alzheimer's disease research and treatment have been hindered by the lack of an easily available, non-invasive diagnostic tool to diagnose the disease as well as to follow the efficacy of treatment," Steven Pacia, director of the Division of Neurology at Lenox Hill Hospital in New York City, told UPI.
"The new PET scanning technique developed at UCLA appears to be both safe and accurate for distinguishing patients with Alzheimer's disease from normals and others with mild memory impairments not due to Alzheimer's disease. Further studies are needed to determine just how specific the test is and whether it can help predict the efficacy of new treatments."
The test outlined in the journal is one of several attempts to non-invasively look into the brain to see how Alzheimer's disease works. William Thies, vice president for medical and scientific relations for the Chicago-based Alzheimer's Association, told UPI:
"A number of efforts are under way to develop better imaging techniques for use in Alzheimer's disease. These include not only FDDNP-PET, but also PET-PIB (Pittsburgh Compound B) and functional MRI.
"For now, the data in this study may prove useful in research, but it is not a definitive 'test' that is ready for public/clinical use. We need testing in larger populations," Thies said.
"The UCLA study is a small window into a much bigger story. Advanced imaging technologies have great potential to improve early detection of Alzheimer's disease and may prove to be powerful tools in testing new therapies.
"A sensitive and accurate method for early Alzheimer's diagnosis that can also track the progression of the disease would help us treat people earlier and greatly speed testing of new drugs in treatment trials. Not having such a test is a major roadblock to efficient drug development."
An estimated 4.5 million Americans have Alzheimer's; that number is expected to grow to as many as 16 million by 2050 as the baby boomers reach the age of highest risk.
