WASHINGTON (Reuters) - An imaging method known as a PET scan may enable
doctors to determine whether a person has "plaques" in the brain that are a
hallmark of Alzheimer's disease, according to a Finnish study published on
Monday.
The brain tissue of people with Alzheimer's disease contains abnormal clumps
called amyloid plaques, but generally doctors cannot be sure if they are there
until the brain is examined after death in an autopsy.
The findings of the small study led by Dr. Ville Leinonen of the University of
Kuopio in Finland indicated that positron emission tomography, or PET, imaging
can detect the plaques.
This shows PET scans may become a useful tool to diagnose Alzheimer's disease, a
fatal and uncurable mind-robbing ailment that is the most common form of
dementia in the elderly, Leinonen said.
"It's very promising," Leinonen, whose study was published in the American
Medical Association's journal Archives of Neurology, said in a telephone
interview.
Experts have been seeking ways to detect the plaques, short of obtaining a
sample of brain tissue, in order to diagnose Alzheimer's in its early stages.
These plaques and irregular knots of fibers in the brain called neurofibrillary
tangles are hallmarks of the disease.
Early diagnosis can allow doctors to give people with Alzheimer's disease drugs
aimed at slowing the cognitive decline associated with the condition.
The study involved 10 people, all of whom had undergone a brain biopsy because
of a suspected abnormal increase of cerebrospinal fluid in the brain.
By examining this brain tissue, the researchers determined that six of the
people had Alzheimer's disease-related plaques in their brain and four had no
such brain changes.
The patients later underwent a 90-minute PET scan.
Following an injection of a chemical "marker" intended to help pinpoint the
brain plaques, the PET scans accurately determined in nine of the 10 people who
had the plaques and who did not, the researchers said.
"It's not 100 percent, but the correlation was very good," Leinonen said.
None of the 10 people in the study had yet developed severe dementia at the time
of the study, the researchers said. They said larger studies are needed to
verify that PET scans can become a common diagnostic tool.
The researchers said another potential use of PET scans would be to monitor
plaque deposits in the brains of people taking part in research into potential
new Alzheimer's drugs to see if the drugs are working.
PET scans currently are used by doctors to detect cancer, cardiac problems such
as damage following a heart attack, brain abnormalities and other purposes.
Other studies have hinted at the promise of imaging methods in diagnosing
Alzheimer's disease. Canadian researchers said last month they used magnetic
resonance imaging, or MRI, scans to locate Alzheimer's-like plaques in rabbits.
An estimated 26 million people have Alzheimer's globally and experts predict
this number will grow to 106 million by 2050.
