The invention relates to the use of a compound comprising the following amino acid sequence X 1 X 2 X 3 X 4 X 5 X 6 X 7 , wherein X1 is an amino acid, except of C, X 2 is an amino acid, except of C, X 3 is an amino acid, except of C, X 4 is an amino acid, except of C, X 5 is an amino acid, except of C, X 6 is not present or any amino acid, X 7 is not present or any amino acid, and wherein X 1 X 2 X 3 X 4 X 5 X 6 is not DAEFRH, said compound having a binding capacity to an antibody being specific for the natural N-terminal Aß42 sequence DAEFRH, and 5-mers thereof having a binding capacity to said antibody being specific for the natural N-terminal Aß42 sequence DAEFRH, for the preparation of a vaccine for Alzheimer's disease.