CX3CL1 and Alzheimer disease: For example, FKN expression declined in mouse model of Alzheimer's Disease (AD),10 in the cerebrospinal fluid of patients with AD,12 in patients with moderate/severe stroke,13 and in the brain of aged rats accompanied by an age‐related increase in microglial activation,37 whereas, FKN expression was reported to be up‐regulated under other conditions.