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AUGUSTA, Ga. – Even while their blood pressures are still normal, overweight male teens may have elevated levels of a hormone known to increase pressures as well as early signs of heart damage, researchers say.

Medical College of Georgia researchers looking at 126 healthy 15- to17-year-olds in high school in Augusta, Ga., found the hormone aldosterone highest among the overweight males. Early intervention could help these young people avoid growing up to be adults with cardiovascular disease, the number one killer in the United States.

“These associations give us reason to question whether we should be screening for and treating high aldosterone in obese males with normal pressures, particularly those with a family history of cardiovascular disease,” MCG Endocrinology Fellow Dayal D. Raja says of the collaborative study with the Department of Pediatrics.

“Our failure to halt the progression of heart damage is attributed to late detection, because early heart damage is usually asymptomatic,” Dr. Raja says. “We have evidence that we could identify individuals early and stop or even reverse that damage. We need more study to confirm our findings and a plan for whom and how to screen.”

This first evidence of elevated aldosterone levels and early heart damage in a pediatric population with normal blood pressure earned Dr. Raja first place in the poster session at the recent American Association of Clinical Endocrinologists 18th Annual Meeting and Clinical Congress in Houston.

Aldosterone, a hormone produced by the adrenal gland, is known to increase blood pressure by increasing sodium and water retention. Despite normal blood pressures, the overweight males had thickened heart walls and an increase in the size of the pumping chamber of the heart, Dr. Raja says. Structural changes in the young hearts can be linked to a lesser-known aldosterone fact: it also promotes inflammation and formation of fibrous tissue in the heart muscle.

Overweight females in the group did not have elevated aldosterone levels or the associated heart damage, Dr. Raja says, noting that estrogen’s cardioprotective effect may have made the difference.

Blood and urine test are available to measure aldosterone levels, but they typically aren’t measured unless a patient on multiple medications still has uncontrolled blood pressure. By then, Dr. Raja says, significant cardiovascular damage may have been done.

It’s more likely, young, overweight people would be told to lose weight, but that isn’t working for most, Dr. Raja says. “We are trying weight loss but we are failing miserably,” he says, noting the worldwide obesity epidemic. In fact, since that’s today’s standard, losing weight is just what these researchers told their study participants to do. Losing weight – if it happens – will decrease aldosterone levels.

Although the exact relationship between increased fat and increased aldosterone is still being sorted out, the latest research suggests that fat cells stimulate the adrenal glands to make more aldosterone, says Dr. Gregory Harshfield, director of MCG’s Georgia Prevention Institute and a hypertension researcher.

As a follow up to Dr. Raja’s study, Dr. Harshfield wants to block aldosterone levels in overweight teens with a family history of cardiovascular disease to determine if it can prevent or reverse dangerous heart changes and forestall hypertension. The GPI already is doing similar studies blocking the kidney’s production of the powerful blood vessel constrictor angiotensin in young people with an impaired ability to secrete sodium.

The landmark 1999 RALE trial illustrated the potential benefit of reducing aldosterone levels even in people already suffering from heart failure. The study of 1,663 patients was halted early because of significantly reduced death rates in those taking the aldosterone-lowering, anti-hypertensive spironolactone. Patients on other anti-hypertensives failed to show as impressive results.

Source: Medical College of Georgia

Drs. Timothy Halliday and Sally Kwak, economics professors at the University of Hawaii at Manoa, recently published a paper in Economics and Human Biology titled, “Weight Gain in Adolescents and Their Peers.” The article examines trends in adolescent body mass index (BMI) in a nationally representative dataset.

In their study, Halliday and Kwak document strong correlations in weight gain between adolescents and their friends, even after controlling for confounding factors such as race, sex and age. While these correlations may be indicative of pupils causing their peers to gain weight, the authors provide evidence that a substantial part of the correlations is a consequence of sorting on BMI.

In addition, they discuss many of the econometric issues in estimating such effects while accounting for growth spurts and difficulties in defining adolescent obesity. Halliday and Kwak discuss policy implications of such findings for school-based interventions to combat obesity. Their work contributes to a growing body of literature studying the impact of peers on student outcomes.

Source: University of Hawaii at Manoa

Children and teens who get less sleep, especially those who spend less time in rapid eye movement (REM) sleep, may be more likely to be overweight, according to a report in the August issue of Archives of General Psychiatry, one of the JAMA/Archives journals.

The obesity rate has more than tripled among children aged 6 to 11 years in the past 30 years, and approximately 17 percent of U.S. adolescents are now overweight or obese, according to background information in the article. Obesity results from an imbalance between calorie intake and energy expenditure from physical activity, but little is known about other factors that can alter this balance. A number of studies have documented an association between fewer hours of sleep and higher body mass index (BMI) in both adults and children.

Xianchen Liu, M.D., Ph.D., of the University of Pittsburgh School of Medicine Department of Psychiatry and Western Psychiatric Institute and Clinic of the University of Pittsburgh Medical Center, and colleagues studied 335 children and adolescents age 7 to 17 years (average age 10.8). For three consecutive nights, participants’ sleep was monitored through polysomnography, which assesses total sleep time, time spent in REM, the time it takes to fall asleep and other variables. Weight and height were measured to calculate BMI.

A total of 49 participants (14.6 percent) were at risk for becoming overweight and 45 (13.4 percent) were overweight. Compared with children at a normal weight, those who were overweight slept about 22 minutes less per night and had lower sleep efficiency (percentage of time in bed that an individual is asleep), shorter REM sleep, less eye activity during REM sleep and a longer wait before the first REM period.

After adjusting for other related factors, one hour less of total sleep was associated with two-fold increased odds of being overweight and one hour less of REM sleep was associated with three-fold increased odds.

“Although the precise mechanisms are currently under investigation, the association between short sleep duration and overweight may be attributed to the interaction of behavioral and biological changes as a result of sleep deprivation,” the authors write. Sleep loss causes changes in hormone levels that may affect hunger, and also provides an individual with more waking hours in which to eat. In addition, sleep loss contributes to fatigue the following day, which may decrease physical activity and calorie expenditure.

“Given the fact that the prevalence of overweight among children and adolescents continues to increase and chronic sleep insufficiency becomes more prevalent in modern society, family- and school-based sleep interventions that aim to enhance sleep hygiene and increase sleep duration may have important public health implications for the prevention and intervention of obesity and type 2 diabetes in children,” the authors conclude. “Furthermore, our results demonstrate an important relationship between REM sleep and high BMI and obesity, suggesting that the short sleep–obesity association may be attributed to reduced REM sleep time and decreased activity during REM sleep.”

Source: JAMA and Archives Journals