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?---- 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
Jacksonville

References:

REFERENCES:
1.

Zhu L, Fratiglioni L, Guo Z, et al. Association of stroke with dementia, cognitiveimpairment, and functional disability in the very old: a population-basedstudy.

Stroke.

1998;29:2094-2099.

2.

Tatemichi TK, Desmond DW, Mayeux R, et al. Dementia after stroke: baselinefrequency, risks and clinical features in a hospitalized cohort.

Neurology.

1992;42:1185-1193.

3.

Schneider JA, Wilson RS, Cochran EJ, et al. Relation of cerebral infarctions todementia and cognitive function in older persons.

Neurology.

2003;60:1082-1088.

4.

Vermeer SE, Prins ND, den Heijer T, et al. Silent brain infarcts and the risk ofdementia and cognitive decline.

N Engl J Med.

2003;348:1215-1222.

5.

Breteler MM. Vascular risk factors for Alzheimer’s disease: an epidemiologicperspective. Neurobiol Aging. 2000;21:153-160.6. Neuropathology Group. Medical Research Council Cognitive Function andAgeing Study (MRC CFAS). Pathological correlates of late-onset dementia in amulticentre, community-based population in England and Wales.

Lancet.

2001;357:169-175.

7.

Snowdon DA, Greiner LH, Mortimer JA, et al. Brain infarction and the clinicalexpression of Alzheimer disease. The Nun Study.

JAMA.

1997;277:813-817.

8.

Straus SE, Majumdar SR, McAlister FA. New evidence for stroke prevention:scientific review.

JAMA.

2002;288:1388-1395.

9.

Yusuf S, Sleight P, Pogue J, et al. Effects of an angiotensin-converting-enzymeinhibitor, ramipril, on cardiovascular events in high-risk patients. The Heart OutcomesPrevention Evaluation Study Investigators.

N Engl J Med.

2000;342:145-153.

10.

Randomised trial of a perindopril-based blood-pressure-lowering regimenamong 6,105 individuals with previous stroke or transient ischaemic attack.

Lancet.

2001;358:1033-1041.

11.

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.

Lancet.

2004;363:757-767.