APOE and dementia: In the cerebrum, astrocyte-sourced APOE assumes a critical function in governing cerebral cholesterol metabolism and facilitating the clearance of β-amyloid.74 Noteworthy is that research has revealed an inverse correlation, where reduced concentrations of plasma APOE are concomitant with an escalated susceptibility to dementia.75,76 Studies have shown a link between BBB integrity and APOE-protein e4 allele,77 but it is not clear in what way and which role the other different polymorphs of the proteins play.