March 2006
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:: Archives :: Publications :: News Room :: Research :: Intranet :: PDF Version ReSeArCh Beyond the walls Gratitudes What's the scoop? |
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Manganese, arsenic and children's learning
An exploratory study led by David Bellinger, PhD, a Children's Hospital Boston Neuropsychology researcher, raises intriguing questions about the cognitive effects of environmental exposure to heavy metals. The study took him to Miami, Okla., located near the Tar Creek Superfund site, where more than 75 million tons of mining waste had been left on the ground's surface. Bellinger and colleagues enrolled 32 fifth- and sixth-grade science students and took samples of their hair, testing the samples for manganese, arsenic and cadmium.
Children with higher manganese and arsenic levels in their hair samples had significantly lower IQ scores—by an average of 10 points—than children with low levels of both metals. They also scored worse on tests of verbal learning and memory, showing poorer recall of words and story lines. The higher the levels of manganese and arsenic in the children's hair, the more poorly they scored. "It was quite surprising to see such a significant statistical correlation in a study this small," Bellinger says.
Bellinger emphasizes that this was only a pilot study: the findings were adjusted for maternal education and hair levels of lead—a metal whose neurotoxicity is established—but not other factors like parental IQ. In addition, unlike lead or mercury, there are no national "norms" for arsenic and manganese exposure with which to compare the levels found in the children's hair. What's clear is that a larger, more in-depth study is needed, and Bellinger will apply for NIH funding to continue the work.
Coauthors on the study, published in theFebruary issue of NeuroToxicology, included Robert Wright, MD, MPH, of Emergency Medicine, and Alan Woolf, PhD, director of Environmental Medicine.
Reducing kids' sugar intake with home deliveries of healthy beverages
When Children's Optimal Weight for Life (OWL) clinic counsels overweight children, one of the first items on the agenda is sugar-sweetened drinks—sodas, sports drinks, "juice drinks," iced teas, lemonades and punches. Now, in the March issue of Pediatrics, researchers report one of the first randomized, controlled trials to test the effects of limiting these fattening drinks through a unique intervention: home beverage delivery.
A team led by endocrinologists Cara Ebbeling, PhD, and David Ludwig, MD, PhD, enrolled 103 children, aged 13 to 18, through a Boston-area high school, offering them a $100 mall gift certificate if they stuck with the six-month study’Äîand all did. Half the teens, picked at random, received weekly deliveries of noncaloric beverages of their own choosing—bottled waters and artificially-sweetened drinks. They were instructed to avoid sugar-sweetened beverages and advised on how to choose noncaloric drinks outside the home. Monthly phone calls and refrigerator magnets ("Think Before You Drink") provided reminders. The remaining teens were a control group: they were asked to continue their usual eating and drinking patterns.
The group receiving beverage deliveries had an 82 percent reduction in consumption of sugary drinks, while intake in the control group remained unchanged. The heavier the teen was at the beginning of the study, the stronger the effect on body weight. Among the heaviest third of teens, the beverage-delivery group had a marked decrease in body mass index (BMI), while the control group had a slight increase—a group-to-group difference of almost 1 pound per month. Other factors affecting obesity—physical activity levels and television viewing—did not change in either group.
Sugary beverages made a good target for several reasons. Intake has surged in recent decades, in step with the rise in childhood obesity. In addition, adolescents who consume sugary drinks often get more than 10 percent of their total calories from them. "Sugary beverages have no nutritional value and seem to make a huge contribution to weight gain," Ebbeling explains.
Finally, more comprehensive weight-loss programs haven't had a substantial effect on body weight. "People often get overwhelmed by nutrition advice and give up," Ebbeling says. "We made it easy for adolescents to replace sugary drinks with noncaloric beverages. To have one targeted and simple message is compelling." Ebbeling and Ludwig are now starting a larger study in 240 overweight students. Coinvestigators include Henry Feldman, PhD, and Stavroula Osganian, MD, ScD, MPH, of Children's Clinical Research Program, and Virginia Chomitz, PhD, from the Institute for Community Health in Cambridge.
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