PPBP and Alzheimer disease: detected differential expressions of AZGP1, fibulin‐1, PPBP, thrombospondin‐1, S100 calcium‐binding protein A8, and S100 calcium‐binding protein A9 in the sera of subjects with AD compared with control subjects using the proteomics approach of isobaric tagging for relative and absolute quantitation (iTRAQ), which indicates that the serum‐based biomarker panel with six proteins might have potential for the detection of AD.