NEW ORLEANS — Increased diastolic blood pressure levels are associated with cognitive impairment, findings from the Reasons for Geographic and Racial Differences in Stroke study suggest.
More than 27,800 participants from REGARDS—a long-term, ongoing study designed to investigate the reasons why stroke-related mortality is more common in portions of the southeastern United States (the “stroke belt”) and among blacks—were included in the analysis. The patients were evaluated in an effort to identify associations between blood pressure indices and cognitive function, as well as any potential interactions between blood pressure indices and age in cognitive function, and any possible racial differences in the relationship between blood pressure and cognition, Dr. Georgios Tsivgoulis, lead author in this portion of the study, reported at the International Stroke Conference 2008.
Findings from previous studies have been conflicting in regard to such interactions, but in this very large cohort of patients, the relationship between diastolic blood pressure levels and cognitive impairment persisted even after adjusting for a host of demographic characteristics, environmental factors, vascular risk factors, health behaviors, and depressive symptoms (odds ratio, 1.08 per 10-mm Hg change for cognitive impairment with increased diastolic blood pressure), said Dr. Tsivgoulis of the University of Alabama at Birmingham.
No interactions were seen between blood pressure and age in impaired cognitive function, nor were racial differences noted in the associations between blood pressure and cognitive status, he said at the conference, which was sponsored by the American Stroke Association.
Participants were at least 45 years of age (mean age, 66 years in the current cohort), and lived in various areas across the United States, with oversampling in the stroke belt. Whites and blacks, as well as men and women, were equally represented.
Cognitive status was assessed using the 6-item screen derived from the Mini-Mental State Examination. Patients with a score of 4 or less were considered to have cognitive impairment. Cognitive status was validated against other cognitive measures for the diagnosis of dementia, and depression was assessed using the Center for Epidemiologic Studies Depression 4-item scale.
The findings suggest that careful monitoring and control of elevated blood pressure may contribute to the preservation of cognitive function, Dr. Tsivgoulis concluded.
The study was funded by the National Institute of Neurological Disorders and Stroke.