Prevalence and predictors of post-stroke dementia defined
MedWire News: The likelihood that stroke patients will develop dementia is strongly associated with multiple strokes and stroke characteristics rather than underlying vascular risk factors, a meta-analysis demonstrates.
The finding highlights the importance of optimizing acute stroke care and secondary prevention as a means of reducing the burden of dementia, say the study authors writing in the journal Lancet Neurology.
The study was undertaken by Sarah Pendlebury and colleagues at the Stroke Prevention Research Unit at John Radcliffe Hospital in Oxford, UK. They searched the literature for prospective cohort studies published between 1950 and 2009 involving patients with symptomatic stroke and reporting pre- and/or post-stroke rates of dementia.
In all, 22 hospital-based and eight population-based cohort studies, including 7511 patients, were included in the analysis.
The pooled prevalence of pre-stroke dementia was 14.1% in hospital-based studies and 9.1% in population-based studies, while the prevalence of post-stoke dementia varied widely, from 7.4% to 41.3% in individual studies.
Much of this variance was explained by differences in factors such as study methods and case mix, Penlebury et al remark.
Importantly, rates of dementia were around three times as high after recurrent stroke than after a first-ever stroke; the pooled cumulative incidence of post-stroke dementia showed a steep rise in the first year followed by a much slower linear increase.
In multivariate analysis, independent predictors for post-stroke dementia included older age, low educational attainment, previous stroke, diabetes, atrial fibrillation, previous cognitive impairment, aphasia, and stroke severity. “Most predictors were related to the stroke itself… and to the complications of stroke,” the researchers write.
They conclude: “Further studies are needed to identify independent predictive factors, to develop a risk factor score for use in clinical practice and trials, and to ascertain the relative contributions of and interactions between degenerative and vascular processes in the causes of post-stroke dementia.”
In an accompanying editorial, Michael Hennerici (University of Heidelberg, Germany) discusses the mechanisms involved in post-stroke dementia and suggests that the systematic treatment of high blood pressure is the best strategy for preventing both stroke and dementia in aging people.
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By Joanna Lyford