WASHINGTON – Children with hypertension performed worse on tests of attention, and verbal and visual recall, according to some early findings of an ongoing study.
A low socioeconomic status seemed to amplify those problems, putting some children at an even higher risk, Dr. Marc Lande said at the annual meeting of the Pediatric Academic Societies.
"These baseline data don’t tell us why these differences occur," he said in an interview. "It is possible that the hypertension itself is causing a problem since we know that the brain is a target organ of hypertension. However, it is also possible that children with cognitive problems are more prone to develop hypertension."
He and his colleagues shared some baseline data from their prospective, multicenter study of neurocognition in children with primary hypertension. The study will eventually enroll 75 children with newly diagnosed primary hypertension and 75 matched normotensive controls. At baseline, both groups will have the same neurocognitive tests. During the following year, the hypertensive children will be treated with lifestyle management and angiotensin-converting enzyme inhibitors, if needed. After a year, all of the children will repeat the same neurocognitive tests.
So far, the cohort includes 37 children with hypertension and 24 controls. Their mean age is 15 years; about half of each group has mothers with less than a high school education – a measure used to indicate lower socioeconomic status. Obesity is present in 70% of the hypertensive group and 58% of the normotensive group. There are no significant differences in IQ, said Dr. Lande, a pediatric nephrologist at University of Rochester (N.Y.) Medical Center.
All of the children had 24-hour ambulatory blood pressure monitoring at baseline. The mean 24-hour systolic blood pressure load was 50% in the hypertensive group and 7% in the normotensive group. The mean 24-hour diastolic load was 22% in the hypertensive group and 5% in the normotensive group – despite the fact that almost 60% of these children were obese.
Dr. Lande presented his baseline data, showing that children in the hypertensive group were already experiencing some neurocognitive differences, compared with the control group.
On the baseline neurocognitive tests, children with hypertension scored worse than the controls on the Rey Auditory Verbal Learning Test (RAVLT) and the Conners’ Continuous Performance Test II (CPT II), although scores on the Spatial Span Forward (SSF) test were not markedly different.
When the comparison was limited to those children with less-educated mothers, the CPT II and SSF performance differences were amplified. The RAVLT performance was largely unaffected.
Findings were similar on three tests of executive function - the CPT II Commissions, Digit Span Backward, and Parent BRIEF Global Executive Composite – with hypertensive children performing worse on all three. When the analysis was limited to children of lower socioeconomic status, the difference was amplified, increasing from a small to moderate or moderate to large effect size.
There were four tests of memory: the RAVLT Short and Long Delay tests, the RAVLT List A Recognition test, and the CogState Maze Long Delay Recall. Overall, children with hypertension had worse performance, with effect sizes ranging from small to large. And again, when the investigators looked only at those children with low maternal education, the effect size between the groups increased. The impact seemed strongest on the RAVLT Recognition Test, in which the effect size increased from small to large.
The baseline findings were unadjusted for any other factors that might influence cognition, Dr. Lande noted. However, they do speak to the need for physicians who treat these children to be aware of the potential for learning problems, especially among children with lower socioeconomic status.
"These results are preliminary findings, which will be further elucidated as the study enrollment goes forward," he said. "We don’t know their clinical significance yet. Until they become more clear, though, clinicians should be aware of the possibility of increased learning problems in their patients with hypertension."
Dr. Lande said he had no financial disclosures