APOE and Alzheimer disease: A previous autopsy [3H]PK11195 study found differences between the brains of pathologically confirmed AD cases and non-AD controls in in vitro [3H]PK11195 binding in only the parietal cortex and the hippocampus.47 In that study all the control cases were APOE4 non-carriers and they did not have AD-pathology in the brain.