Sickle Cell Can Take Heavy Toll on Littlest Victims
Disease may cause 'silent' strokes that impair young children's mental development, study says
THURSDAY, March 28, 2002 (HealthDayNews) -- Infants with sickle cell disease may suffer impaired mental development because of strokes caused by the illness.
That's the conclusion of a new study from Duke University that also says parental expectations for children with the condition could affect the infants' intellectual development.
"This is the first study to look at the cognitive development of infants with sickle cell disease," says lead author Robert J. Thompson Jr., a psychology professor at Duke University Medical Center.
Previous studies focused on school-age children and adolescents with sickle cell disease, which disproportionately affects African-Americans. And those studies found that the kids were prone to strokes that affected their ability to think and reason.
The Duke study is the first time researchers have looked for that problem in infants and toddlers.
Thompson and his colleagues studied 89 African-American children and their parents who went to the University of North Carolina Comprehensive Sickle Cell Center. The children's mental and physical development were measured when they were 6 months old and again at 12 months, 24 months and 36 months.
Parents also completed questionnaires that asked them to measure their stress levels, knowledge of their child's disease, and their own psychological adjustment to the situation.
To test the infants' mental development, the researchers had them perform different tasks and make judgments. For example, the researchers hid a cube under a cup to see if an infant noticed the cube was gone and whether he or she was able to figure out where the cube went.
The results showed that when they were 2 years old, 29 percent of the children were well below normal test results for the general population of children the same age.
"By the time we got to two years of age, you could see there was a decline from the levels they had been functioning at previously. The decline seemed to occur between 12 and 24 months," Thompson says.
The study appears in the April issue of the Journal of Pediatric Psychology.
Thompson says the study seems to confirm what he suspected -- that infants with sickle cell disease are prone to strokes, just like older children. These can be "silent strokes," where there are no obvious symptoms.
But strokes may not be the only influence on the cognitive development of these children, Thompson adds.
"We've tried to focus on the role that parenting might play as a possible way to intervene and try to make things better," he says.
Citing the parental surveys, he says a sense of hopelessness and lack of extra effort to help their children seemed to slow the infants development.
"This makes sense. If a person doesn't feel as if actions they take are going to make a difference, that's likely to affect what they do," Thompson says.
He stresses that this is a preliminary study, however. There was no control group of infants without sickle cell disease to offer direct comparisons.
But Thompson says this study could serve as a foundation for more research into how sickle cell disease affects infant cognitive development.
Ronald Brown, a professor of pediatrics at the Medical University of South Carolina, says the Duke study offers new insights into sickle cell's potential impact on infants.
"A lot of the research has been done with school-age children. By looking at infants and toddlers, it allows us to extend the [medical] literature," Brown says.
Sickle cell disease is an inherited blood disorder characterized by defective hemoglobin, a component of red blood cells that helps those cells carry oxygen. Normal red blood cells are smooth and donut-shaped. But the defective hemoglobin can cause the red blood cells to become sickle-shaped.
This shape prevents the sickle-shaped red blood cells from traveling through small blood vessels. The red blood cells stack up and cause blockages that deprive organs and tissue of oxygen-carrying blood. That can cause pain and damage to tissue and organs.
About 72,000 people in the United States, mostly African-Americans, have sickle cell disease and about 2 million Americans carry the sickle cell trait, says the U.S. National Heart, Lung, and Blood Institute.