CCL2 and Cognitive impairment: Our meta-analysis revealed significant relationships of blood CXCL10, CXCL9, CCL27, and CCL15, as well as CSF CCL2 with Alzheimer’s patients compared with cognitively normal control subjects, of blood CXCL9 and CCL1 with Alzheimer’s disease compared with mild cognitive impairment, and of blood CX3CL1 with mild cognitive impairment compared with healthy subjects.