Small BMI change in overweight children could have big blood pressure impact

ScienceDaily (Oct. 15, 2010) — Small changes in weight can make bigger differences in the blood pressure for overweight children, compared to those at normal weight, according to a new study.

Researchers tracked blood pressure, height and weight of 1,113 children over time, with the longest follow-up exceeding 10 years. They then compared the children's body mass index (BMI, a measure of body weight) to national charts adjusted for age, sex and height. Kids with BMIs in the 85th percentile or higher are considered overweight.

"Below the 85th percentile, BMI effects on blood pressure appear to be fairly linear," said Wanzhu Tu, co-author of the study. "After the 85th, particularly after the 90th percentile, the BMI effect became noticeably stronger."

Analysis indicated the effect on systolic blood pressure of overweight boys' BMI percentile was 4.6 times that in normal-weight boys. Systolic blood pressure is a measure of the force of the blood pumped by the heart against the arteries when the heart is contracted. Findings were similar for diastolic pressure in boys, and both readings in girls. Diastolic blood pressure is a measure of the force of the blood against the arteries when the heart is relaxed and is the top number in a blood pressure reading.

In normal-weight children, BMI percentile and blood pressure remained related but the associations were weaker.

BMI and blood pressure studies typically don't separate normal-weight and overweight children, so findings tend to overestimate BMI's effect on blood pressure in normal-weight children but underestimate it in overweight kids, Tu said.

"Because our estimate of the BMI effect was much greater in overweight kids, the results suggest that even a modest reduction in BMI may produce a much greater benefit in blood pressure in overweight kids," Tu said. "Conversely, a small increase in BMI could put them at much greater risk of blood pressure elevation."

The paper was presented October 15 at the American Heart Association's High Blood Pressure Research 2010 Scientific Sessions (HBPR 2010) held in Washington, DC, USA.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Heart Association, via EurekAlert!, a service of AAAS.

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Children with high blood pressure more likely to have learning disabilities, study finds

ScienceDaily (Nov. 10, 2010) — Children who have hypertension are much more likely to have learning disabilities than children with normal blood pressure, according to a new University of Rochester Medical Center (URMC) study published in the journal Pediatrics. In fact, when variables such as socio-economic levels are evened out, children with hypertension were four times more likely to have cognitive problems.

"This study also found that children with hypertension are more likely to have ADHD (attention deficit hyperactivity disorder)," said Heather R. Adams, Ph.D., an assistant professor of Neurology and Pediatrics at URMC, and an author of the study. "Although retrospective, this work adds to the growing evidence of an association between hypertension and cognitive function. With 4 percent of children now estimated to have hypertension, the need to understand this potential connection is incredibly important."

Among the study's 201 patients, all of whom had been referred to a pediatric hypertension clinic at URMC's Golisano Children's Hospital, 101 actually had hypertension, or sustained high blood pressure, determined by 24-hour ambulatory monitoring or monitoring by a school nurse or at home. Overall, 18 percent of the children had learning disabilities, well above the general population's rate of 5 percent. But the percentage among those without hypertension was closer to 9 percent, and among those with hypertension, the rate jumped to 28 percent. All of the children were between 10- and 18-years-old, and the children's learning disability and ADHD diagnoses were reported by parents.

This study is part of a series of hypertension studies by Golisano Children's Hospital researchers, led by Principal Investigator Marc Lande, M.D., a pediatric nephrologist, but it was the first that included children with ADHD. Previous studies excluded them because ADHD medications can increase blood pressure. Researchers included them this time because, although it is possible that some of the children's hypertension was caused by medications, it is also possible that the higher rate of ADHD among children with hypertension is a reflection of neurocognitive problems caused by hypertension. Twenty percent of the children with hypertension had ADHD whereas only 7 percent of those without hypertension had ADHD among the study participants. And even when ADHD was factored out of the analyses, there was still a higher rate of learning disabilities in the hypertensive, compared to the non-hypertensive group of children.

"With each study, we're getting closer to understanding the relationship between hypertension and cognitive function in children," Lande said. "And this study underscores the need for us to continue to tease out the potential risk children with hypertension have for learning difficulties at a time when learning is so important. It may be too early to definitively link hypertension and learning disabilities, but it isn't too early for us, as clinicians, to ensure our pediatric patients with hypertension are getting properly screened for cognitive issues."

The study was funded by a grant from the National Institutes of Health. The authors have no conflicts to disclose.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Rochester Medical Center.

Journal Reference:

H. R. Adams, P. G. Szilagyi, L. Gebhardt, M. B. Lande. Learning and Attention Problems Among Children With Pediatric Primary Hypertension. Pediatrics, 2010; DOI: 10.1542/peds.2010-1899

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here