Factors related to atherosclerosis are believed to be the reason stroke deaths are significantly higher in the "stroke belt," which includes Alabama, Arkansas, Georgia, Indiana, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennesse and Virginia.
Scientists have questioned whether people in these states have more strokes because they have more risk factors for atherosclerosis, the build-up of fat-containing deposits in the inner walls of arteries. These risk factors - high blood pressure, smoking, diabetes, high cholesterol and high triglycerides in the blood - are strongly related to lifestyle habits such as diet and exercise.
Researchers from the University of California San Francisco examined whether there is also a stroke belt for children. Overall, stroke in children is rare.
"By studying children, a group whose stroke rates are not affected by atheroslerotic risk factors, we can address the question of whether these risk factors are enough to explain the stroke belt," said Heather J. Fullerton, M.D., clinical instructor of neurology and pediatrics at the University of California San Francisco.
The researchers, analyzing death certificates for 1979 - 1998, found that people under age 20 in stroke belt states had a 21 percent higher risk of death from stroke compared with people of the same age in other states. The risk was 20 percent higher among people over age 25 in that region during the same period.
"This means that we should look at stroke risk factors that are applicable to both children and adults when attempting to explain the stroke belt," Fullerton said. "We might look predominantly toward environmental or cultural factors, such as differences in water or soil, diet, socioeconomic status and genetics."
Childhood stroke is relatively rare, each year occurring in about two to three of every 100,000 children, Fullerton said.
"The overall rates are low, and the differences we're pointing out are small enough that people in the stroke belt states shouldn't be alarmed that their children are at great risk," she said. "However, this research points to the fact that we don't understand much about childhood stroke."
Known risk factors include sickle cell disease, congenital heart defects and inherited conditions that increase blood clotting.
As found in earlier studies, this research documented more fatal strokes in black children than white children, mirroring racial differences in adults.
"However, the stroke belt isn't simply due to racial disparities in stroke risk. We found that within each racial group the same geographic disparity exists," Fullerton said.
A stroke occurs when a blood vessel leading to the brain becomes clogged (an ischemic stroke) or bursts (a hemorrhagic stroke), depriving brain cells in the affected area of oxygen. Rates for both types of stroke were higher rates in children in the stroke belt.
The current research only documents fatal strokes. However, geographic differences are believed to largely reflect an increased occurrence of stroke rather than disparities in survival, she said.
Co-authors are Jacob S. Elkins, M.D.; Yvonne W. Wu, M.D., M.P.H.; and S. Claiborne Johnston, M.D., Ph.D.
The National Institute of Neurological Diseases and Stroke funded the study.