Research on the pathophysiological characteristics of Alzheimer disease (AD
) over the past decade has been directed toward the ultimate goal of develo
ping a disease-modifying treatment to control or prevent the disease. A rep
ort recently published in Nature(1) describes for the first time a treatmen
t that may both prevent and treat the progression of Alzheimer disease. The
treatment ironically involves immunization with the pathological p-amyloid
peptide itself to generate an immune response targeted against the amyloid
plaques in the brain. These findings have raised a number of scientific an
d clinical questions that are discussed below.