First identified by Wu and colleagues, PCSK9 was found to promote neuronal cell death by increasing caspase activity and suppressing ApoER2 expression.303 Consistent with this finding, the silencing of PCSK9 in mice provided a defense against neuronal apoptosis induced by cerebral ischemia, thereby mitigating the advancement of brain damage.304 However, the exact association between PCSK9 and AD remains nebulous. This evidence concerns the gene PCSK9 and Alzheimer disease.