Alzheimer's beta amyloid peptide (29-40/42) C-terminal fragments have physical and chemical properties related to those of fusion peptides of viral proteins. The fusion of liposomes can be induced by these peptides in vitro. Beta amyloid peptide (29-40/42) is vital for amyloid and apoE interactions and plays a protective role against beta amyloid aggregate formation and/or against the interaction of those aggregates with cellular membranes.