ACAN and Alzheimer disease: We previously found that PNNs are extensively reduced in the 5xFAD mouse model, which develops amyloid pathology starting at age 1.5 months,46 as well as in human AD cortical tissue.11 To validate previous observations, we stained 4- and 8-month WT and 5xFAD brain tissue with Amylo-Glo to detect amyloid plaques, ACAN, which recognizes the core protein of the PNN CSPG ACAN, and WFA, which binds to GAG chains of CSPGs, to visualize PNNs.