The clinical importance of white matter hyperintensities on brain magnetic resonance imaging: systematic review and meta-analysis.
OBJECTIVE
To review the evidence for an association of white matter hyperintensities with risk of stroke, cognitive decline, dementia, and death.


METHODS
Systematic review and meta-analysis.


METHODS
PubMed from 1966 to 23 November 2009.


METHODS
Prospective longitudinal studies that used magnetic resonance imaging and assessed the impact of white matter hyperintensities on risk of incident stroke, cognitive decline, dementia, and death, and, for the meta-analysis, studies that provided risk estimates for a categorical measure of white matter hyperintensities, assessing the impact of these lesions on risk of stroke, dementia, and death.


METHODS
Population studied, duration of follow-up, method used to measure white matter hyperintensities, definition of the outcome, and measure of the association of white matter hyperintensities with the outcome.


RESULTS
46 longitudinal studies evaluated the association of white matter hyperintensities with risk of stroke (n=12), cognitive decline (n=19), dementia (n=17), and death (n=10). 22 studies could be included in a meta-analysis (nine of stroke, nine of dementia, eight of death). White matter hyperintensities were associated with an increased risk of stroke (hazard ratio 3.3, 95% confidence interval 2.6 to 4.4), dementia (1.9, 1.3 to 2.8), and death (2.0, 1.6 to 2.7). An association of white matter hyperintensities with a faster decline in global cognitive performance, executive function, and processing speed was also suggested.


CONCLUSIONS
White matter hyperintensities predict an increased risk of stroke, dementia, and death. Therefore white matter hyperintensities indicate an increased risk of cerebrovascular events when identified as part of diagnostic investigations, and support their use as an intermediate marker in a research setting. Their discovery should prompt detailed screening for risk factors of stroke and dementia.
Debette
Stéphanie
S
Clinical Neuroscience, St George's University of London, London. sdebette@bu.edu
Markus
H S
HS
D002561:Cerebrovascular Disorders / Q000473:pathology*; D003072:Cognition Disorders / Q000473:pathology* / Q000517:prevention & control; D015140:Dementia, Vascular / Q000473:pathology / Q000517:prevention & control; D018450:Disease Progression; D006801:Humans; D008137:Longitudinal Studies; D018810:Magnetic Resonance Angiography; D008833:Microcirculation; D011379:Prognosis; D012307:Risk Factors; D020521:Stroke / Q000473:pathology / Q000517:prevention & control