APOC3 and dementia: Although it is not known if apoE in HDL without apoC3 is causally associated with lower risk of dementia or cardiovascular disease, metabolic studies have shown that while HDL that contains apoE is cleared from the circulation more than 7-fold faster than HDL that lacks apoE, the clearance of HDL is attenuated if apoE coexists with apoC3.15 Thus, at least for clearance, apoC3 effectively counteracts the effect of apoE—similar to what we have now observed for both CHD and dementia.