People living in the Stroke Belt may have shared risk factors for stroke mortality and impaired brain function.
Residents of the Stroke Belt—a Southern portion of the United States with a significantly elevated stroke mortality rate—also have a greater incidence of cognitive decline compared with people from other regions of the country, according to research published in the May 26 online Annals of Neurology.
“Regional disparities in cognitive decline mirror regional disparities in stroke mortality, suggesting shared risk factors for these adverse outcomes,” reported Virginia G. Wadley, PhD, Associate Professor of Medicine at the University of Alabama at Birmingham, and colleagues. “Efforts to promote cerebrovascular and cognitive health should be directed to the Stroke Belt.”
In 1965, the Stroke Belt first appeared in medical literature to describe the Southeastern region of the US where stroke mortality rates were 50% higher than all other US regions. According to the CDC, the age-adjusted annual rate of stroke mortality among adults 35 and older in the eight Stroke Belt states (Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee) was, on average, 125 per 100,000 persons, compared with a rate of 96 per 100,000 persons in the remaining 40 contiguous states and the District of Columbia (2000 to 2006).
Findings From the REGARDS Study
The Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, led by principal investigator George Howard, DrPH, recruited more than 30,000 American adults, ages 45 or older, from 2003 through 2007 and is following them for stroke and cognitive decline. REGARDS participants included 56% from the Stroke Belt states and 44% from the remaining states in the continental US, including the District of Columbia, which researchers collectively termed “non-Belt” states.
For their analysis on cognitive decline, the investigators included 23,913 REGARDS participants, consisting only of African Americans (38%) and European Americans (62%) who had reported no history of stroke at baseline and also had normal cognitive status at the first assessment.
“Our study is the first to document a higher incidence of cognitive impairment in the Stroke Belt compared to remaining US regions,” Dr. Wadley commented.
The researchers assessed brain function with use of the Six-Item Screener (SIS)—a test of global cognitive function that includes item recall and temporal orientation. SIS scores range from 0 to 6, with a score of 4 or less representing cognitive impairment.
Results showed that 8.1% of participants showed cognitive impairment at their most recent assessment, during a mean of 4.1 years following the initial assessment. Stroke Belt residents had a greater likelihood of cognitive impairment than did non-Belt residents (odds ratio, 1.18); all demographic factors and time between first and last assessments independently predicted impairment. The risk of cognitive impairment was 18% higher in residents of the Stroke Belt than in those living in non-Belt states after adjusting for age, sex, race, and education level.
Regional Patterns Can Help Shape Prevention Efforts
The researchers suggest that future studies should examine the impact of migration patterns, urban versus rural residence, socioeconomic factors, and educational quality on cognitive decline. “Investigating regional patterns that contribute to modifiable risk factors affecting cognitive decline will allow for prevention and intervention efforts that are geographically concentrated,” concluded Dr. Wadley. “Information obtained from the REGARDS study can be used to develop services for older Americans at both local and national levels to improve outcomes for those most vulnerable to diminished cognitive function.”