What is the risk of dementia in patients who have had an ischemic stroke?
What is the risk of dementia in patients who have had an ischemic stroke?And which therapies are most effective in reducing this risk?---- MDPopulation-based epidemiologic studies show thatthe risk of dementia is 4 to 6 times higher in patientswho have had a stroke than in those whohave not.1 In hospitalized cohorts, dementia developsin a quarter to a third of patients 3 months aftera stroke,2 and up to 60% have impairment in at least 1 cognitivedomain. Compared with persons who have not hada stroke, patients with cerebrovascular disease have a 2- to10-fold higher risk of incident dementia, particularly whenmultiple infarcts are present.3 In the general population,silent or unrecognized brain infarcts also raise the risk ofdementia in the subsequent 3 years,4 perhaps becausethey are a marker of high risk of additional infarcts.5Cognitive decline in patients with cerebrovasculardisease can result from the stroke itself when a large volumeof brain is affected by ischemia or hemorrhage orwhen the lesion, because of its location in a strategic area,interrupts brain circuits that are critical for cognition.Alternatively, vascular and neurodegenerative changes,which are common in the brains of elderly persons,6 cancoexist and lead to a "mixed dementia." These pathologicprocesses act synergistically to impair cognition.7Clearly, strategies that reduce the incidence of strokewill reduce the burden of cognitive impairment and dementia.Primary prevention strategies for stroke include lifestylechanges (a healthful diet, regular exercise, smokingcessation) and aggressive management of risk factors, includinghypertension, nonvalvular atrial fibrillation, and hypercholesterolemia.8 Proven secondary prevention strategiesinclude the use of antihypertensive agents, particularlyangiotensin-converting enzyme inhibitors and thiazide diuretics,9,10 and antiplatelet agents, as well as management ofatrial fibrillation and symptomatic high-grade carotid arterystenosis. Data from available studies suggest that statintherapy may reduce the risk of stroke by 25%.11 Trials totest the effectiveness of statins in secondary stroke preventionare currently under way, as are trials of vitamin therapyto reduce homocysteine levels.---- Jos G. Merino, MD
Assistant Professor of Neurology
University of Florida College of Medicine
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Randomised trial of a perindopril-based blood-pressure-lowering regimenamong 6,105 individuals with previous stroke or transient ischaemic attack.
Collins R, Armitage J, Parish S, et al. Effects of cholesterol-loweringsimvastatin on stroke and other major vascular events in 20536 people withcerebrovascular disease or other high-risk conditions.