Researchers experimenting with mice bred to develop the plaques associated with Alzheimer's disease have succeeded in clearing the plaques from the animals' brains. Previous work had shown that plaque formation can be prevented with a vaccine, but the new study, which appears in the March issue of the journal Nature Medicine, demonstrates for the first time the clearance of existing plaques. Brian Bacskai of Massachusetts General Hospital and his colleagues found that surgically applying anti-plaque antibodies directly to the animals' brains erased 70 percent of the plaques in only a few days. Also of note, the team was first to observe plaques in a living animal, using a new device called a multi-photon microscope.

Exactly how the neurons near the cleared plaques will be affected is not yet known, but further work may shed light on this question. "Once we can see where a plaque is, we can also ask whether the neurons in their area are healthy or not," team member Bradley Hyman remarks. "The real key is to understand how to improve the function of the brain."