Laminin and specific laminin-derived protein fragments are disclosed as potent inhibitors of Alzheimer's disease type amyloidoses. A specific region is identified within laminin which interacts with the Alzheimer's disease beta-amyloid protein and contributes to the observed inhibitory and therapeutic effects.A prominent .about.130 kilodalton band in laminin was found in human serum and cerebrospinal fluid which primarily interacted with A.beta. as determined by ligand blotting methodology. This .about.130 kilodalton laminin fragment is known as the E8 fragment and is also believed to consist of the globular domains of the laminin A chain. The interaction of specific laminin fragments such as the newly discovered .about.130 kDa protein is believed to bind A.beta. in biological fluids and keep it in a soluble state.