FLT1 and Alzheimer disease: Using single-cell RNA-seq transcriptome analysis, a recent report revealed that ECs in the AD brain showed increased expression of immune markers and angiogenic growth factors and their receptors, including FLT1 (VEGFR1) compared to controls (Mahoney et al., 2019), suggesting a potential link between an abnormal EC angiogenic state and BBB abnormalities seen in AD patients.