Strategies to Lower the Risk of Stroke-Related Dementia

What is the risk of dementia in patients who have had an ischemic stroke? And which therapies are most effective in reducing this risk? —— MD Population-based epidemiologic studies show that the risk of dementia is 4 to 6 times higher in patients who have had a stroke than in those who have not.¹ In hospitalized cohorts, dementia develops in a quarter to a third of patients 3 months after a stroke,² and up to 60% have impairment in at least 1 cognitive domain. Compared with persons who have not had a stroke, patients with cerebrovascular disease have a 2- to 10-fold higher risk of incident dementia, particularly when multiple infarcts are present.³ In the general population, silent or unrecognized brain infarcts also raise the risk of dementia in the subsequent 3 years,⁴ perhaps because they are a marker of high risk of additional infarcts.⁵ Cognitive decline in patients with cerebrovascular disease can result from the stroke itself when a large volume of brain is affected by ischemia or hemorrhage or when 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 can coexist and lead to a “mixed dementia.” These pathologic processes act synergistically to impair cognition.⁷ Clearly, strategies that reduce the incidence of stroke will reduce the burden of cognitive impairment and dementia. Primary prevention strategies for stroke include lifestyle changes (a healthful diet, regular exercise, smoking cessation) and aggressive management of risk factors, including hypertension, nonvalvular atrial fibrillation, and hypercholesterolemia. ⁸ Proven secondary prevention strategies include the use of antihypertensive agents, particularly angiotensin-converting enzyme inhibitors and thiazide diuretics, ^9,10 and antiplatelet agents, as well as management of atrial fibrillation and symptomatic high-grade carotid artery stenosis. Data from available studies suggest that statin therapy may reduce the risk of stroke by 25%.¹¹ Trials to test the effectiveness of statins in secondary stroke prevention are currently under way, as are trials of vitamin therapy to reduce homocysteine levels. —— José G. Merino, MD
Assistant Professor of Neurology
University of Florida College of Medicine
Jacksonville