Children with high blood pressure may be at risk for learning disabilities, according to a new study.

In the study, children with high blood pressure, or hypertension , were three to four times more likely to have a learning disability than those without hypertension. The results were true regardless of whether children were taking medications for attention deficit hyperactivity disorder, or ADHD, which can increase blood pressure .

The researchers had previously shown that kids with high blood pressure perform worse on tests of mental performance than those without hypertension.

The findings underscore the importance of identifying children with hypertension, and understanding how the condition may affect the brain, the researchers said. About 4 percent of children in the United States have hypertension, but many cases may go undiagnosed.

"Physicians need to be even more aware that hypertension is a growing problem in children," said study researcher Heather R. Adams, a pediatric neuropsychologist at the University of Rochester in New York. They should also keep in mind there may be an association between high blood pressure and learning disabilities, she said.

Children and hypertension

Adams and her colleagues reviewed data from 201 children, ages 10 to 18, who were referred to a hypertension clinic because of their high blood pressure. About half had hypertension while half did not (a referral does not necessarily mean a child has hypertension.)

Of the kids with hypertension, 28 percent had learning disabilities, while just 9 percent of those without hypertension did.

The percentage of children with learning disabilities in the general population is around 5 percent.

The researchers said that they have only shown an association, and not a cause-effect link.

And they still don't know how hypertension could contribute to learning problems. One hypothesis is that hypertension influences the blood vessels in the brain, which in turn impact how blood moves through the brain, Adams said.

Future work

The researchers are now conducting a follow-up study, to see if treating the children's high blood pressure for one year improves their mental performance, Adams said. If they see a reversal of cognitive problems, the researchers would have stronger evidence that hypertension contributes to problems with cognitive performance.

The study is published in the Dec. 1 issue of the journal Pediatrics.

Pass it on: Hypertension is a growing problem in children, and evidence is building that it is linked with problems learning and trouble performing on cognitive tests.

Follow MyHealthNewsDaily staff writer Rachael Rettner on Twitter @Rachael_MHND.