PCSK9 inhibitors in neurodegenerative disorders: mechanisms, therapeutic potential, and clinical implications.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a role in hepatic cholesterol metabolism via low density lipoprotein receptor degradation. PCSK9 inhibitors have revolutionized lipid-lowering therapy, providing robust reduction of cardiovascular risk. Large-scale randomized controlled trials and long-term extensions (e.g., FOURIER and EBBINGHAUS trials) have shown no significant adverse effects of PCSK9 inhibitors on neuropsychological testing or patient-reported cognitive outcomes, even with prolonged and intensive lowering of low-density lipoproteins. Pre-clinical studies also suggest PCSK9 as a key regulator of neurobiological processes, including synaptic plasticity, amyloid-beta clearance, neuroinflammation, and blood-brain barrier integrity. Human genetic studies revealed complex, sometimes conflicting associations between PCSK9 variants and risk of Alzheimer's disease, Parkinson's disease, vascular dementia, and amyotrophic lateral sclerosis. In this review, we highlight the pathophysiologic mechanisms, emerging experimental therapeutics and clinical implications of PCSK9 inhibition in neurodegenerative disorders. Long-term adequately powered trials with robust neuropsychological, biomarker, and imaging endpoints, as well as mechanistic studies in human-derived models are needed to establish the cardiovascular and neurocognitive implications of PCSK9 inhibition and guide precision medicine strategies for those at elevated risk of neurodegeneration.