According to this hypothesis, in animal models of cognitive impairment induced by a high-fat diet, the administration of a PCSK9 inhibitor was associated with a reduction in Aβ1-42-formation, microglial activation, hippocampal apoptosis, and lower cognitive decline, although the results were not consistent across the studies [73,74,75,76]. The gene discussed is PCSK9; the disease is Cognitive impairment.