Dilemma of early Alzheimer's testing, which may not ever develop
Human brain projected on man's head. Photographer: Hans Neleman
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Last Updated: 89 days ago
Kathryn Becker wants to know if, like her mother, she won't recognize her own daughter one day.
The retired Navy engineer who taught herself two programming languages decided to undergo tests that may reveal her future. She went through a spinal tap and brain imaging that revealed she has biological components that may cause Alzheimer's disease.
The early diagnosis means the memory loss that makes it hard for Becker to use an ATM or find the right kitchen drawer for a spatula will likely evolve into full-blown Alzheimer's. But it's not a guarantee of that end result and brings no medicine proven to stop the progression, much less cure, a disease that affects 5.4 million Americans.
Doctors and scientists argue over when the diagnosis should be given and to whom. Officials of the National Institute on Aging say the uncertainty of the disease's evolution means the earliest preclinical findings should only come into play during clinical trials for drugs aimed at treating Alzheimer's before it emerges.
The chances of preclinical stages becoming full-blown Alzheimer's increase if people already suffer memory loss or other cognitive lapses. But some scientists contend people with no symptoms shouldn't be told of the preclinical findings, even if tests are positive.
"It doesn't mean they're going to get Alzheimer's. It means they're probably at a higher risk," said Dr. Creighton Phelps, director of the Alzheimer's Disease Centers Program at the National Institute on Aging. "You can't tell them what to do with the information because we can't be sure of what it means."
In the early stage testing, neurologists use spinal taps and brain imaging to hunt for the presence of proteins called tau as well as fragments called beta amyloid. The biomarkers cause plaque and tangled clusters that are always found in Alzheimer's patients, although scientists don't fully understand the connection.
Neurologists combine the procedures with cognitive tests and MRI scans designed to detect shrinking in the part of the brain that forms, organizes and stores memories.
If people already show significant memory loss, the tests can suggest they will likely develop full Alzheimer's. But the value of using the preclinical findings to predict the progression toward the disease for people who show few symptoms is uncertain. Some people diagnosed with the preclinical condition never develop full Alzheimer's.
"They are perhaps at a higher risk, but they're not definitely going in this direction," Phelps said. "Thirty percent of the people who die of old age have amyloid in the brain but have no symptoms of Alzheimer's."
Genetic tests can also indicate elevated risks. The growing need for testing is driven by the failure of medications designed to attack Alzheimer's in its fully formed stage. Now, drugs are being tested in clinical trials to assess their effectiveness earlier.
"We have been treating the disease too late," said Ken Kosik, an Alzheimer's researcher at the University of California, Santa Barbara. "The idea is that if we're going to find a cure, we have to start early, before the disease starts."
Dr. James Sutton, an Oxnard, Calif., neurologist participating in two clinical trials, tells people they may be headed toward dementia and there's little that current medicine can do about it.
"I'm diagnosing people with preclinical Alzheimer's and leaving them to fend for themselves," said Sutton, who formed a support group to help his patients cope.
"It's like we're opening up a Pandora's box," Sutton said. "But we're only opening it up a little way."
Several neurologists said they will perform the imaging procedures and genetic tests for patients who have reason to think Alzheimer's lies ahead but will also make sure people know the answers they gain may not be complete or absolute.
"I would want the person to have a good reason," said Kosik, the neurologist and researcher. "I've done it because families wanted some sort of certainty so they can try to consider their future with a full deck of cards. They get the certainty that this looms ahead of them with greater likelihood than some other people."
The doctors themselves struggled with the dilemma. They ask themselves the same question: Would they want to know?
Kosik won't answer, saying the scenario has too many nuances for an easy response. Sutton's answer is no. He knows his future may hold Alzheimer's or other health risks. He's not ready to face it until it happens.
"I don't want to believe that anything's ever going to happen to me," he said. "I have an irrational optimism in the future."
To learn more about early testing for indicators that may be linked to Alzheimer's disease:
(Reach Ventura County Star reporter Tom Kisken at firstname.lastname@example.org.)
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