The invention relates to the use of a compound comprising the following
amino acid sequence X.sub.1X.sub.2X.sub.3X.sub.4X.sub.5X.sub.6, wherein
X.sub.1 is an amino acid, except of C, X.sub.2 is an amino acid, except
of C, X.sub.3 is an amino acid, except of C, X.sub.4 is an amino acid,
except of C, X.sub.5 is an amino acid, except of C, X.sub.6 is an amino
acid, except of C, and wherein X.sub.1X.sub.2X.sub.3X.sub.4X.sub.5X.sub.6
is not DAEFRH, said compound having a binding capacity to an antibody
being specific for the natural N-terminal A.beta.42 sequence DAEFRH, and
5-mers thereof having a binding capacity to said antibody being specific
for the natural N-terminal A.beta.42 sequence DAEFRH, for the preparation
of a vaccine for Alzheimer's disease.