The invention relates to the use of a compound comprising the following amino acid sequence X1X2X3X4X5X6X7, wherein X1 is an amino acid, except of C, X2 is an amino acid, except of C, X3 is an amino acid, except of C, X4 is an amino acid, except of C, X5 is an amino acid, except of C, X6 is not present or any amino acid, X7 is not present or any amino acid, and wherein X1X2X3X4X5X6 is not DAEFRH, said compound having a binding capacity to an antibody being specific for the natural N-terminal Aβ42 sequence DAEFRH, and 5-mers thereof having a binding capacity to said antibody being specific for the natural N-terminal Aβ42 sequence DAEFRH, for the preparation of a vaccine for Alzheimer's disease.