Long-Term Cognitive Safety of Achieving Very Low LDL Cholesterol with Evolocumab

BACKGROUND: Concerns persist regarding the cognitive safety of achieving very low levels of low-density lipoprotein (LDL) cholesterol. Although short-term studies are reassuring, the long-term cognitive effects of sustained exposure to very low LDL cholesterol levels through combined proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibition and statin therapy remain unknown. METHODS: This prospective study enrolled a subset of adults with atherosclerotic cardiovascular disease who had completed a neurocognitive substudy (EBBINGHAUS) of a placebo-controlled randomized trial of evolocumab (FOURIER) and were eligible for a long-term open-label extension. The objective of this current study was to assess the long-term effect of evolocumab on cognitive function. Cognitive function was assessed annually, and the primary end point was change from baseline in executive function within each group, measured using the spatial working memory strategy index score (range, 4-28), with lower scores indicating better performance. RESULTS: A total of 473 patients out of the 1974 patients in the parent EBBINGHAUS study were enrolled and additionally followed for a median of 5.1 years (maximum follow-up since original random assignment 7.2 years). The median age was 62 years; 70% were male, and 91% were White. At 12 weeks into the open-label extension period, median LDL cholesterol across the overall population was 35 mg/dl (interquartile range, 21-55 mg/dl). Treatment with evolocumab was not associated with a change in executive function during the open-label extension in either patients who were originally randomly assigned to and continued evolocumab (mean±standard deviation of 0.1±2.8, P=0.49) or patients originally randomly assigned to placebo who then started on evolocumab (-0.1±2.5, P=0.64). At the final study visit, executive function scores were similar between randomly assigned groups (17.5±3.7 and 17.3±3.7, respectively). CONCLUSIONS: Exposure to very low levels of LDL cholesterol, achieved via PCSK9 inhibition and statin therapy, was not associated with cognitive impairment through long-term follow-up. Further studies are needed to assess the generalizability to adults at higher risk of dementia.