Abstract
Neurodegenerative diseases such as Alzheimer's (AD), Parkinson's (PD), Huntington's (HD), and multiple sclerosis (MS) involve progressive neuronal loss driven by dysregulated neurotransmission, neuroinflammation, oxidative stress, and mitochondrial dysfunction. Cholesterol metabolism has emerged as a critical factor involved with both central and peripheral dysregulation contributing to pathology. This review synthesizes current evidence on cholesterol's role in neurodegeneration and evaluates the therapeutic potential of statins, which act via cholesterol-dependent and other pleiotropic mechanisms. A PubMed search covering 1985-2025 publications was conducted using terms related to neurodegenerative diseases, statins, cholesterol metabolism, neuroinflammation, oxidative stress, mitochondrial dysfunction, and neuroprotection. Studies were selected to highlight mechanistic insights into cholesterol regulation in the nervous system and clinical data on statin use. Neuronal loss in neurodegeneration is driven by processes including excitotoxicity, inflammation, and mitochondrial dysfunction. Excessive reactive oxygen species activate apoptotic pathways involving BAX, BAK, and p53. Dysregulated cholesterol metabolism is a significant contributor: In AD, the ApoE allele ε4 (ApoE4) links elevated cholesterol to amyloid-β (Aβ) accumulation and cognitive decline; in PD, cholesterol shows mixed effects, with some studies suggesting protection and others linking high levels to α-synuclein aggregation and mitochondrial impairment. In HD reduced cholesterol biosynthesis correlates with neuronal loss, while MS associates with elevated cholesterol and cognitive dysfunction. Statins, widely used cholesterol-lowering agents, reduce Aβ production, enhance its clearance, and improve synaptic function. Beyond lipid lowering, they exert anti-inflammatory, antioxidant, and anti-apoptotic effects. Clinical outcomes remain mixed, with benefits influenced by statin type, dose, treatment duration, disease stage, and patient genetics. Statins show multifaceted neuroprotective potential through cholesterol-dependent and independent pathways. While preclinical data are encouraging, clinical evidence is heterogeneous. Long-term, stratified trials are needed to clarify efficacy, and tailoring therapy to disease-specific mechanisms may offer a viable strategy for mitigating neurodegeneration and enhancing neuronal survival.