Unraveling Alzheimer's

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The observation was important, says Dr. Virginia Lee, a pathologist at the University of Pennsylvania School of Medicine, because "it showed that tangles alone can result in neurodegenerative disease." Now researchers are trying to transplant the defective human gene into mice. The hope is that they can create a strain of mice that develop both plaques and tangles. Then they would be able to study tangles at will and eventually get a better idea of how plaques and tangles interact to unleash the devastation of Alzheimer's disease.

As much as has been learned in the past few years about how Alzheimer's progresses, a lot more study needs to be done. The latest research could wind up proving that plaques and tangles are not causes of death, but more like tombstones--they tell you where people are buried but are not responsible for killing them. Or it could be that the only way to prevent Alzheimer's is to stop the plaques from forming decades before any symptoms appear.

Even if scientists figure out precisely how Alzheimer's destroys brains, it is not clear that they will be able to stop it. But it's also clear that no one will be able to treat the disease--let alone cure it--until they do.