CX3CL1 and Cognitive impairment: Furthermore, they show that hTau mice expressing ckFKN (hTau/CX3CL1105Δ) had similar phospho-tau pathology and cognitive deficits as hTau; Cx3cl1−/− mice, both of which had significantly greater phospho-tau pathology and cognitive deficits than hTau mice expressing endogenous FKN.