Cynthia Lemere, a neurologist at Brigham and Women's Hospital and Harvard Medical School who researches Alzheimer's, points out another potential issue with the vaccine: Even with the novel design, it may not be enough to avoid the more aggressive immune response.

Lemere suggests that the solution may be a vaccine that uses a shorter segment of Aß. One end of the protein is important for producing antibodies against it, whereas another part of Aß triggers the more aggressive immune response. A vaccine that only uses the fragment of Aß that produces antibodies may eliminate the chance of the harsher immune reaction.

The ultimate test will be whether the vaccine works well in humans. Until then, Bowers plans to refine the vaccine in more mouse trials to make it as safe as possible. The study, funded by the National Institutes of Health, were published in the journal Molecular Therapy.