PYY and Alzheimer disease: Furthermore, trend line post-hoc tests demonstrated significant progressive declines in brain insulin (P=0.017), GLP-1 (P=0.016), and PYY (P=0.02) with increasing AD stage, AD stage-associated trend reductions in ghrelin (P=0.089) and PP (P=0.087), and significant increases in leptin (P=0.005) with AD severity.