APOE and type 2 diabetes mellitus: As HDL functions can be compromised by aging, cardiovascular disease and T2DM (Riwanto and Landmesser, 2013), it will be important in the future to understand how HDL purified from aged cognitively healthy individuals, AD subjects, or patients with cardiovascular risk factors may affect cerebrovascular function and Aβ accumulation especially in combination with apoE.