We have used AT-8 and Aβ immunohistochemistry to assess hyperphosphorylated tau/NFT and Aβ/senile plaque pathologies, developed and characterized 3xTg-AD mice with wildtype or reduced PTPRD expression and assessed results of treatments with our (a) PTPRD phosphatase inhibitor pentilludin, (b) lead PTPRD positive allosteric modulator (PAM) quercetin and (c) drug candidate PTPRD PAM active metabolite 6BrQ. The gene discussed is MAPT; the disease is Alzheimer disease.