New Scanning Methods Help Detect Alzheimer's Early Signs
By VANESSA FUHRMANS
Staff Reporter of THE WALL STREET JOURNAL
It wasn't until Alzheimer's began stealing stretches of Mary Lockhart's memory that she knew she had it. On the way to her doctor's near her home in Oklahoma City, she one day no longer knew the way. She argued with her husband over things she couldn't remember saying. She forgot simple words, mistaking the "sidewalk" for the "hallway."
Then 55 years old, she didn't dream it could be Alzheimer's. "I wondered about a brain tumor," she says. But after several tests and an MRI, the diagnosis was nearly as harsh: Alzheimer's so advanced that her doctors said she might have only five years to live. "If I knew I was at risk and there was a test I could have taken to catch this earlier, I would have wanted it," she says, now 62.
Until recently, those tests haven't existed. Alzheimer's infiltrates the brain years before dementia and other symptoms set in, replacing healthy tissue with clumps of plaque and tangles of dead neurons. Doctors can't spot that, except in an autopsy. By the time telltale symptoms develop, there is little current drugs can do.
But a new molecule that sets Alzheimer's wreckage aglow on PET, or position-emission tomography, scans for the first time in live patients could transform doctors' ability to detect the disease -- even years before symptoms occur. That could give patients a crucial head start in stalling Alzheimer's terrifying progression. It is also shaping up to be an effective tool for scientists in testing new, more powerful treatments.
The substance, which University of Pittsburgh researchers spent more than 12 years concocting, works like this: Doctors administer the compound to patients intravenously, then place them under the scanner to record detailed images of the brain. The dye is similar to those used in autopsies of Alzheimer's patients but manages to do what researchers thought for years was an insurmountable hurdle: safely pass from the bloodstream into the brain.
Once in the brain, it latches onto the tiny fibrils of plaque, yet steers clear of normal tissue. In the first human studies of the compound, to be presented next week at the International Conference on Alzheimer's and Related Disorders in Stockholm, the front and temporal lobes of nine patients glowed with neon-red mounds of plaque. In comparison, the scans of five healthy people showed little or no sign of the compound.
"It's definitely not subtle," says William E. Klunk, associate professor of psychiatry at the University of Pittsburgh and member of the team that developed the compound.
The advance builds on remarkable progress recently in using PET scanners and MRI machines to track early signs of Alzheimer's. Unlike X-rays or CT-scans, PET scans and MRI machines zero in on the glucose that fuels brain activity.
In another study to be presented in Stockholm, researchers at the Good Samaritan Regional Medical Center in Phoenix, Arizona, were able to use PET technology to detect abnormally lower brain activity already in 20- and 30-somethings with a high genetic risk of developing late-onset Alzheimer's -- even though they performed just as well on cognitive thinking and memory tests as those without the risk factor.
Still, those tests show only that the brain is faltering. The "Pittsburgh compound," as researchers are calling it, reveals the disease's underlying pathology, letting doctors see concrete evidence of the disease and how it is progressing.
It is possible such diagnostic tools could be approved and widely available in three to five years, Alzheimer's researchers estimate. That could allow patients to maximize available treatments before dementia and other symptoms set in. But many warn of the implications of the ability to detect the disease early on while only having limited means to treat it.
"We need some caution in telling young people they might have Alzheimer's when we're already struggling to get people with mild symptoms to come forward," says Elizabeth Rimmer, director of Alzheimer's International, an umbrella organization of national Alzheimer's patient associations. She wonders whether such tests could prevent some people from getting health insurance, a job or a mortgage. In addition, people might torture themselves with the findings, seeing imminent doom every time they misplace the car keys.
It's more likely that such tools as the "Pittsburgh compound" will make their mark first as a critical aid in testing and screening the dozens of potential Alzheimer's treatments in development. A number of companies already have inquired about the compound, its researchers say. That's because without the ability to test how exactly potential drugs stall or stop the disease, drug makers can only guess which ones to keep trying to develop.
Only a test that shows the actual damage the disease inflicts on the brain can lead to the holy grail of Alzheimer's research, a treatment that stops the disease before it ever unleashes its awful symptoms. "Advances haven't come because we've gotten better at treating vegetative-state Alzheimer's patients," Dr. Klunk says. "They've come because we're learning to treat people earlier." |
