An increasing number of children are developing high blood pressure and this may have a serious impact on their cognitive abilities, such as verbal and memory skills, a new study has found.

High blood pressure (hypertension) has been increasing among children in recent years and this is thought to be largely due to the rising prevalence of childhood obesity. While it is already known that hypertension can affect an adult's brain, few studies have looked at the effect on children's brains.

US researchers decided to look into this further. They carried out cognitive tests on 150 children aged between 10 and 18, half of whom had recently been diagnosed with high blood pressure.

Children who were known to have conditions that affect cognitive skills, such as ADHD or sleep disorders, were excluded.

"We wanted to make sure that if we found differences between children with and without hypertension, it was likely associated with the hypertension itself, not any of these other factors," explained Dr Marc Lande of the University of Rochester.

The study found that children with high blood pressure performed worse on certain cognitive tests compared to the children without high blood pressure. These tests measured visual and verbal memory, verbal skills and processing speed.

The study also noted that more children with sleep problems had hypertension, intensifying the effect of poor sleep on cognition.

The researchers emphasised that the children with hypertension were not found to be cognitively impaired, however they did not perform as well as the children without high blood pressure.

"In the future, we want to better understand if there are physical changes to the brain in children who have hypertension that could explain these cognitive test results," Dr Lande said.

If more is known about such physical changes, researchers may then be able to assess whether antihypertensive treatments could improve cognitive performance in children with high blood pressure and reverse or even prevent future adult hypertension-related problems.

Details of these findings are published in The Journal of Pediatrics.