A method for identifying compounds that inhibit amyloidal-beta precursor protein processing in cells, comprising contacting a test compound with a GPCR polypeptide, or fragment thereof, and measuring a compound-GPCR property related to the production of amyloidal-beta peptide. Cellular assays of the method measure indicators including second messenger and/or amyloid beta peptide levels. Therapeutic methods,and pharmaceutical compositions including effective amyloidal-beta precursor processing-inhibiting amounts of GPCR expression inhibitors, are useful for treating conditions involving cognitive impairment such as Alzheimers Disease.