As Alzheimer's disease progresses, so-called amyloid plaques build up in the brain and the nerve cells are destroyed. The diseased organ slowly wastes away (see image), leading to memory loss and other cognitive disabilities. Although there are competing theories about what causes this devastating damage, many scientists have placed the blame on an accumulation of amyloid beta peptides. A new report in today's issue of Nature helps prove that idea. Moreover, Peter St. George-Hyslop, director of the Center for Research in Neurodegenerative Diseases at the University of Toronto, and his colleagues report that vaccinations of the peptides may in fact serve to prevent and treat Alzheimer's.

The scientists developed transgenic mice having amyloid plaques in their brain tissue and cognitive impairments like those seen in people with Alzheimer's disease. Earlier studies showed that immunizing such animals with amyloid beta peptides could remove amyloid plaques. But in this round of experimentation, the scientists further demonstrated that the injections could actually block the production of the plaques and forestall learning difficulties. "Not only were we able to clean up the brain tissue, but we also prevented the behavioral consequences of Alzheimer's," St. George-Hyslop says. "Obviously it is more important that a treatment or prevention in humans be able to block the clinical dementia." The scientists say that the amyloid beta plaque vaccination is ready for human testing.