Association of Pancreatic Polypeptide with Mild Cognitive Impairment Varies by APOE ε4 Allele. Alzforum, 09 Oct 2015 Roberts RO, Aakre JA, Cha RH, Kremers WK, Mielke MM, Velgos SN, Geda YE, Knopman DS, Petersen RC.