Prevention of stroke and dementia with statins: Effects beyond lipid lowering.

Stroke is a major cause of mortality and morbidity. The epidemiologic association between elevated serum cholesterol and stroke risk is controversial. However, recent secondary prevention studies with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have demonstrated a significant reduction in ischemic stroke without an increase in hemorrhagic stroke. Statins probably reduce stroke by a variety of mechanisms, including modulation of precerebral atherothrombosis in the aorta and the carotid artery, thus preventing plaque disruption and artery-to-artery thromboembolism. Statins also improve endothelial homeostasis by increasing the bioavailability of nitric oxide, which orchestrates the paracrine antiatherosclerotic functions of the endothelium. Studies in experimental models of ischemic stroke show that statin therapy reduces brain infarct size and improves neurologic outcome by directly upregulating brain endothelial nitric oxide synthase. Putative anti-inflammatory actions of statins may also contribute to neuroprotection and stroke prevention. Although the clinical benefit of statins largely depends on lowering low-density lipoprotein cholesterol, accumulating data indicate that many of the pleiotropic effects of statins are attributable to the cellular consequences of depletion of intermediates in the cholesterol biosynthetic pathway (isoprenoids). These molecules play fundamental roles in cell growth, signal transduction, and mitogenesis. In addition to reducing stroke risk, emerging data suggest that statins may reduce dementia. Further studies are needed to fully address the role of statins in the prevention of stroke in patients without established vascular disease and the role of cholesterol modulation in the treatment of dementia.