Investigations of intranasal insulin as an AD treatment have also shown mixed results, with an acute insulin treatment showing memory improvement in APOE4− MCI and AD patients, but not APOE4+ MCI and AD patients [126], while a chronic insulin treatment has shown memory improvement in APOE4+ MCI and AD patients, but not APOE4− MCI and AD patients [127]. This evidence concerns the gene APOE and Alzheimer disease.