May 1, 2006 A new brain-imaging method allows physicians to diagnose Alzheimer's before its onset. A radioactive dye is injected in the blood and travels to the brain, where it attaches to plaque deposits of amyloid, a protein believed to cause Alzheimer's. The dye makes amyloid plaque look yellow in a Positron Emission Tomography (PET) scan.
PITTSBURGH--Alzheimer's disease deprives millions of Americans of their memories. There is no cure, but catching the disease in its earliest stages could help patients lead longer, healthier lives. Now there's a new way to diagnose the disease earlier than ever.
For Arnie Begler, wedding day photos bring back bitter-sweet memories of his mother. "Today, unfortunately, she doesn't remember that wedding anymore."
She doesn't remember, because Alzheimer's robbed her of her memory. Begler's mother was diagnosed nine years ago, but a diagnosis relies on symptoms usually appearing in late stages of the disease. Now, neurologists and imaging specialists may be able to detect the disease long before symptoms appear.
This image shows pictures never before seen of amyloid plaque deposits, proteins in the brain believed to kill brain cells and cause Alzheimer's.
William Klunk, a geriatric psychiatrist at University of Pittsburgh Medical Center, says "For the first time you're able to see something that you had to wait until after death to see, so you can see whether or not these plaques are in the brain and roughly how much is there."
Patients are injected with a radioactive dye called Pittsburgh Compound-B -- or PIB. Once it reaches the brain, PIB attaches to plaque. Then, a PET scan reveals areas with the most plaque build-up.
"It would be potentially extremely useful and powerful to detect the presence of early disease," says Chester Mathis, a chemist at University of Pittsburgh.
And fighting the disease earlier is something Begler hopes to see for future generations.
Traditionally, definitive diagnosis of Alzheimer's could only be determined through an autopsy. The distinguishing factor between Alzheimer's disease and other dementias is the presence of amyloid plaques -- believed to cause the death of brain cells.
BACKGROUND: A novel imaging agent has the potential to diagnose Alzheimer's disease in living patients by binding to the telltale beta-amyloid deposits in the brains of those who suffer from it. Called Pittsburgh Compound-B, or PIB, the contrast agent is used in conjunction with PET scans. This non-invasive technique can give researchers information never before available about how and where the disease progresses in the brain, as well as the efficacy of treatment.
WHAT THEY'VE FOUND: The pattern of PIB retention in the brain suggests that amyloid plaques formed by Alzheimers appearing first in the frontal cortex areas, then progressing to the parietal and temporal cortex before ravaging the occipital and sensory-motor cortex. This may explain why memory and judgment are often the brain functions first affected with the onset of the disease.
ABOUT ALZHEIMER'S: Alzheimer's is the most common form of dementia, a brain disorder that primarily affects the elderly. Scientists still aren't sure what causes the disease, and there is no cure. It is named after a German doctor, Alois Alzheimer, who noticed (in 1906) anomalies in the brain tissue of a woman who had died of a strange mental illness. There were abnormal clumps (called amyloid plaques) and tangled bundles of fibers, both of which are the most common signs of Alzheimer's. Other brain changes can occur. Nerve cells die in areas of the brain vital to memory and other mental abilities, and the connections between nerve cells are disrupted, impairing thinking and memory.
SYMPTOMS: Alzheimer's is a slow-moving disease, and in its earliest stages, may merely appear to be mild forgetfulness, and confused with age-related memory change. There may be problems remembering recent events or activities, or the names of familiar people or objects. As the disease progresses, the forgetfulness becomes more severe, interfering with daily activities, such as brushing one's teeth. There are problems speaking, understanding, reading or writing, and eventually the brain damage becomes so severe as to require total care.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.