Researchers may be one step closer to diagnosing Alzheimer’s disease while the patient is still alive, increasing the opportunity for treatment sooner.
A positive identification is typically not done until after death, when an autopsy can be conducted. While a patient is alive a series of tests may be given to determine brain decline, a less exact method of diagnosis.
For the first time, researchers, using clinical-grade magnetic resonance imaging scans (MRIs), have located Alzheimer’s-like plaque in rabbits.
John Robarts of Ontario’s Roberts Research Institute believes that may have application to humans.
"Although some of the technology used to generate these images was designed specifically for rabbits, this preliminary discovery hints at the promise of using clinical MRI scanners to visualize plaques in people with Alzheimer's," he said in a statement.
The MRI scanner was customized with special hardware that generates a microimagine, detecting structures smaller than 50 microns, and which is more sensitive to iron-containing structures.
Previously, amyloid plaques have only been seen or "imaged" using a high powered MRI scanners used only on animals, or with a PET scan using marker chemicals.
This is the first time the amyloid plaques, characteristic of Alzheimer's disease, have been seen using a conventional MRI.
In the study, rabbits were fed a high-cholesterol diet. That caused the brain to form amyloid plaques. After two years the rabbits’ brains were scanned where researchers saw black spots or signal voids in the brain, particularly the hippocampus where memory is stored.
An autopsy then positively identified amyloid plaques in the same dark areas. Each cluster also had high levels of iron, which is believed to cause the MRI signal voids. Rabbits fed a normal diet did not develop the black spots in the brain.
Plaque buildup is a marker for Alzheimer’s and dementia, though may not be the cause.
MRI technology is less expensive than other imaging technology and more widely distributed. An additional benefit is that there is no radiation involved in the scan.
This study was also unveiled at the International Conference on Alzheimer’s Disease in Chicago.
Other researchers at the conference questioned whether research on rabbits can be easily transferred to humans. Research using high-field MRIs on mice, have not been able to see the plaques in humans.
In another study, this one from the Mayo Clinic in Rochester, Minnesota, a computer program was used to analyze information on MRI scans looking for the amount of atrophy in the human brain. In that research, data from 101 people was gathered and analyzed. The data was taken within four years of their death and after they died.
Fibrous tangles in the brain, another characteristic of Alzheimer's, were measured with the help of an MRI scan, customized with an algorithm that extracts atrophy information from a 3-D MRI scan.
The technique helped distinguish between the Alzheimer’s brain and normal brain with 90 percent accuracy. The program is known as STAND (Structural Abnormality Index) score.
From the University of Kansas Medical Center, MRI brain imaging pointed out the importance of cardiorespiratory fitness in Alzheimer’s patients. More physically fit patients had less brain atrophy in the areas of the brain first affected by the disease.
"These MRI studies show that researchers are moving closer to accurate early detection of the disease, and that we may soon be able to use this technology to determine who is at greater risk," William Thies of the Alzheimer's Association said. #