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Incident cognitive impairment is elevated in the stroke belt: The REGARDS Study

July 8, 2011 Comments off

Incident cognitive impairment is elevated in the stroke belt: The REGARDS Study
Source: Annals of Neurology

Regional disparities in cognitive decline mirror regional disparities in stroke mortality, suggesting shared risk factors for these adverse outcomes. Efforts to promote cerebrovascular and cognitive health should be directed to the Stroke Belt. ANN NEUROL 2011

The Reasons for Geographic and Racial Differences in Stroke (REGARDS) study is an epidemiological study following a cohort of US adults for stroke and cognitive decline. In reports from REGARDS, self-reported stroke symptoms in the absence of diagnosed stroke were considered as potential markers of ischemic changes. Such symptoms, reported by 18% of REGARDS participants,1 were associated with a 24% increased risk of prevalent cognitive impairment after controlling for age, sex, race, education, and region of residence.2 Decrements in cognitive function may serve in some cases as a proxy for unrecognized small strokes,2 a notion that is supported by demonstrated associations between magnetic resonance imaging-defined silent brain infarcts, cognitive deficits, and incident dementia.3–7 It is not known, however, whether incidence of cognitive impairment is elevated in the Stroke Belt region of the United States, a region of the southeastern United States first described in 1965 as having 50% higher stroke mortality rates than the remaining United States.8 Centers for Disease Control and Prevention state statistics from 2000 to 2006 reveal that among adults aged 35 years and older, age-adjusted annual rates of stroke mortality in the 8 Stroke Belt states were, on average, 125 per 100,000, compared to an average rate of 96 per 100,000 in the remaining 40 contiguous states and the District of Columbia.9 During the same period, age-adjusted stroke hospitalization rates among Medicare beneficiaries aged 65 years and older followed a similar pattern of higher concentration in the Stroke Belt.9

It is plausible that incidence of cognitive impairment might be elevated in the Stroke Belt due to subclinical strokes and cerebrovascular disease as well as to precursor or concomitant risk factors for both stroke and cognitive impairment, such as hypertension, diabetes, kidney disease, and metabolic syndrome.10–16 The purpose of the present analysis from the REGARDS study was to examine incident impairment in cognitive screening status in the southern Stroke Belt region relative to the remaining 40 contiguous states. Among participants who had intact cognitive screening status at baseline and no history of stroke, we predicted regional differences in incident cognitive impairment that reflect well-documented regional differences in stroke incidence and mortality. Specifically, we hypothesized that there would be greater occurrence of incident impairment in cognitive screening performance in the Stroke Belt relative to the rest of the United States.

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