As rates of obesity among children and adolescents have exploded in the United States, we’ve begun to see diseases once exclusive to old age take hold in young people as well.

For instance, Healthline reported in December that one in five U.S. young people had unhealthy cholesterol readings.

High blood pressure has also been on the rise in young people and it’s most common in those who are overweight or obese.

A study published today in the journal Pediatrics begins to make the case that extra weight causes high blood pressure in children and adolescents.

“I am reluctant to use a word as strong as causality, but our results do suggest a causal relationship,” lead researcher Emily Parker, Ph.D., MPH, of HealthPartners Institute for Education and Research, told Healthline.

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Three Years of Study

Parker’s study examined the electronic health records (EHRs) of 101,000 children and adolescents over three years of medical care and was able to show that blood pressure varies with body mass index (BMI).

Even in young people whose weight is considered healthy, weight gain led to an increase in blood pressure. Those who are most overweight were most likely to have blood pressure high enough to qualify as full-fledged hypertension, which also requires three consecutive abnormal readings.

“The development of hypertension was extremely rare — less than 0.2 percent developed hypertension,” Parker said.

But the rare outcome was clearly connected with obesity. Obese children and adolescents doubled their risk of developing hypertension and those who were severely obese more than quadrupled their risk.

On the bright side, weight loss resulted in lower blood pressure.

“Children and adolescents who decreased from obese to healthy weight or overweight to healthy weight had significant changes in [blood pressure] percentiles, as did those who decreased from severely obese to obese, overweight, or healthy weight,” the study reported.

The findings add to the calls for prevention of obesity in young people.

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Thanks, Obama (and EHRs)!

The basic question — does excess weight help cause high blood pressure in youth — has been surprisingly difficult to answer directly.

“This question can only be answered with longitudinal data. And because hypertension is so rare in kids it has to be a very large population so you have enough kids to detect the outcome of interest,” Parker said.

The rise of EHRs, whose use was mandated as part of President Obama’s signature healthcare reform, made the long-term research more economical.

Patients gave yearly consent for healthcare systems to share data from their EHRs, scrubbed of identifying information. And with that, researchers were able to create a study with 101,000 participants. Before EHRs, they would have had to recruit the patients and measure BMI and blood pressure themselves.

The best existing studies on young people and high blood pressure based their findings on a single abnormal reading because multiple readings over six months were too difficult to get.

“There are many advantages to using EHR data,” Parker said. “It is relatively cheap because we are using existing data, and we have access to a large and diverse population, which allows us to look at outcomes that are rare like pediatric hypertension, or exposures that are rare like severe obesity.”

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