Transgenic mice express human membrane metallo-endopeptidase (MME) under the direction of the mouse calcium/calmodulin-dependent protein kinase II alpha (Camk2a) promoter. Transgene expression is approximately 8 fold relative to wildtype controls, as detected by quantitative Western blot analysis and protease activity assay. The levels of soluble alpha beta-amyloid X-40 and soluble alpha beta-amyloid X-42 are reduced in 2 to 3 month old transgenic mice. (J:87150)