For decades public health researchers have known that individuals living in the American South displayed an increased risk of stroke and other forms of cardiovascular disease.
A new study finds that individuals living in this region also have a greater incidence of cognitive decline compared to other regions of the country.
The region is generally considered to be an 11-state cluster including Alabama, Arkansas, Georgia, Indiana, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia. Researchers believe shared risk factors are to blame for the increased chance of cardiovascular events and cognitive decline.
Risk factors have been hypothesized to include increased rates of hypertension, low socioeconomic status, high fat diet, cultural lifestyle, quality of health care facilities, smoking, and infections.
In 1965, the “Stroke Belt” first appeared in medical literature to describe the southeastern region of the U.S. where stroke mortality rates were 50 percent higher than the remaining U.S. regions.
In the new study, called The Reasons for Geographic and Racial Differences in Stroke (REGARDS), Principal Investigator George Howard, Dr.PH., recruited over 30,000 U.S. adults aged 45 or older from 2003 through 2007 and is following them for stroke and cognitive decline.
REGARDS participants included 56 percent from the Stroke Belt states and 44 percent from the remaining states in the continental U.S., including the District of Columbia, which researchers collectively termed “non-Belt” states.
For their report on cognitive decline, the investigators included 23,913 REGARDS participants, made up only of African-Americans (38 percent) and European-Americans (62 percent) who reported no history of stroke at baseline and had normal cognitive status at the first assessment.
“Our study is the first to document higher incidence of cognitive impairment in the Stroke Belt compared to remaining U.S. regions,” said researcher Virginia Wadley, Ph.D.
Researchers assessed brain function using 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 indicate that 8.1 percent of participants showed cognitive impairment at their most recent assessment, over a mean of 4.1 years following the initial assessment. Stroke Belt residents had a greater likelihood of cognitive impairment than non-Belt residents.
Risk of cognitive impairment was 18 percent higher in residents of the Stroke Belt than in those living in non-Belt states after adjusting for the influences of age, sex, race, and education level. The research team suggests 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,” Wadley said.
“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.”