PPARG and Alzheimer disease: Furthermore, activation of PPAR-γ in the brains of AD mice initiate a coupled metabolic cycle with the Liver X Receptor to increase brain apolipoprotein E levels, which promotes the ability of microglial cells to phagocyte and degrade both soluble and fibrillary Aβ (Mandrekar-Colucci et al., 2012; Yamanaka et al., 2012).