Herein, we describe stage-related ECS deficits in an AD mouse model: CB1 levels with [18F]FMPEP-d2 imaging are lost at the early-stage prominently in females, undergo a compensatory increase, and are deficient again at the late-stage pathology in both sexes; [18F]MAGL-2102 availability increases only in the early-stage pathology in males. The gene discussed is CNR1; the disease is Alzheimer disease.