Observations from studies suggesting worse results in neurocognitive tests and a lower psychomotor processing speed in patients treated with statins [157], better scores achieved in neuropsychological tests in a group of healthy adults with higher level of LDL [158] or increased concentration of PCSK9 in the cerebrospinal fluid in patients suffering from Alzheimer’s disease (AD) [159] were the causes of analyzing the potential adverse effects of PCSK9 inhibitors on the CNS. This evidence concerns the gene PCSK9 and Alzheimer disease.