SLC2A1 and Alzheimer disease: Because GLUT1 expression is downregulated with BBB degeneration, low levels of FDG in the BBB are indicative of BBB pathologies, and can identify AD and other dementias (Shivamurthy et al., 2015; Montagne et al., 2016a; Sweeney et al., 2018, 2019; Bouter et al., 2019; Ou et al., 2019).