APOE and Alzheimer disease: In parallel, two other biomarkers, Leptin and PYY, have shown increased levels in the AD/APOE ε4+ subgroup at both time points, strongly suggesting that in the AD/APOE ε4+ subgroup, these analytes may represent a stable biomarker alternative in the APOE ε4− carrier individuals, while seeking for a biomarker panel sufficient for AD detection.