Abstract: The invention provides a method for the treatment of a patient having a more severe form of Alzheimer's disease (AD), where the severe form of AD is characterized by pathogenic deposits of amyloid beta peptide (A?), comprising the administration of an immunogenic fragment of A? capable of inducing an immune response in the form of antibodies to specific to the pathogenic deposits of A? and, in particular, to neurotoxic forms of A? including N-terminally truncated forms of A?. The invention further provides a method for selecting a suitable immunogenic fragment of A? for the treatment of a more severe form of AD.