As compared to other PPARs, PPAR-β/δ seems to be most expressed in the brain (Cimini et al. 2005), and expression of PPAR-β/δ was reduced in the brains of AD patients similar as PPAR-α but the expression of gene for PPAR-γ was selectively upregulated (de la Monte and Wands 2006) (Fig. 3). Here, PPARD is linked to Alzheimer disease.