by Loren Bonner
, DOTmed News Online Editor
Presenters at the 59th annual SNM meeting in Miami Beach, Fla., unveiled an array of breakthrough research and new techniques to detect evidence of Alzheimer's in living patients -- including, possibly, in asymptomatic populations.
Researchers know that beta-amyloid plaque can build up in the brain several years before an individual shows any signs of dementia. And many scientists believe that this plaque can kill vital neural pathways that are responsible for language, memory and behavior.
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"Molecular imaging can detect signs of Alzheimer's disease many years before patients develop dementia. It can do this because it can target beta-amyloid," says Dr. Christopher Rowe, a lead investigator for the Australian Imaging, Biomarkers and Lifestyle study of aging and professor of nuclear medicine at Austin Hospital in Melbourne, Australia.
In one of the studies presented by Rowe's team, PET was combined with an F-18 imaging agent. Subjects who showed high levels of the tracer during imaging had an 80 percent chance of developing Alzheimer's within two years, according to study findings.
Research also found that beta-amyloid plaque in the brain was not only involved in the pathology of Alzheimer's disease but also preceded mild cognitive function.
"For those with mild memory problems who had a positive scan, 66 percent of these people progressed to dementia over three years. This compares to only 7 percent of those with a negative scan," says Rowe.
Rowe highlighted findings on this study at the meeting, which included 194 healthy elderly subjects, 92 subjects with mild cognitive impairment, and 70 subjects with Alzheimer's. C-11 Pittsburgh compound B (PiB) combined with PET was used to gauge amyloid burden in the brain.
"This is an opportunity to find the patient who has Alzheimer's and intervene with treatments as they become available," says Rowe.
He pointed out that being able to correctly identify which patients have Alzheimer's and which don't is a necessary stepping stone for developing potential drugs and therapies to treat the disease.
Alzheimer's can only be detected in a patient after death-- by studying postmortem brain samples with beta-amyloid plaque.
Currently, no reliable treatment exists for Alzheimer's patients and the screening tests that do exist are unreliable and limited in their ability to identify the disease early.
New biomarkers emerge
Any PET amyloid imaging test must begin with a biomarker. This year's SNM meeting presented some promising amyloid imaging agents in development that will help clinicians detect Alzheimer's in living patients.