Kids appear to process caffeine -- the stimulant in coffee, energy drinks and soda -- differently after puberty. Males then experience greater heart-rate and blood-pressure changes than females, a new study suggests.
Although the differences are small, "even what we might consider low doses of caffeine can have an effect on heart rate and blood pressure in kids," said study lead author Jennifer Temple, an associate professor at the University at Buffalo in New York.
About three out of four U.S. children consume caffeine each day, but little is known about their safety.
For this study, about 100 preteens and teens consumed the equivalent amount of caffeine found in a can of soda or a cup of coffee. Half were 8- and 9-year-olds; the others were 15 to 17 years old.
"Although our data do not suggest that this level of caffeine is particularly harmful, there is likely no benefit to giving kids caffeine, and the potential negative effects on sleep should be considered when deciding which beverages to give to kids," Temple said.
The researchers found that caffeine lowered the heart rates of the kids past puberty by about 3 to 8 beats per minute. Boys were affected more than girls.
Caffeine also boosted systolic blood pressure in boys past puberty to a greater extent than girls, although the effect was slight.
"This suggests that boys may be more sensitive to the effects of caffeine than girls," Temple said.
Girls also experienced different heart-rate and blood-pressure changes throughout their menstrual cycle, the researchers said. This further supports their theory that sexual maturity changes the body's reaction to caffeine.
Caffeine's effects were relatively similar between boys and girls before puberty.
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Diets rich in protein appear to reduce a person's risk of stroke, particularly if it's a lean animal protein like fish, a new analysis suggests.
People with the highest amounts of animal protein in their diets were 20 percent less likely to suffer a stroke, compared with those who ate little to no protein, said study author Xinfeng Liu, of Nanjing University School of Medicine in Nanjing, China.
For every additional 20 grams per day of protein that people ate, their risk of stroke decreased by 26 percent, the researchers found.
"If everyone's protein intake were at this level, that would translate to more than 1.4 million fewer deaths from stroke each year worldwide, plus a decreased level of disability from stroke," Liu said in a news release from the American Academy of Neurology.
The researchers concluded that animal protein offers more than twice the protective benefit against stroke as protein from vegetable sources.
Stroke experts cautioned against taking the study's findings too literally, however. Many animal protein sources also come with high levels of saturated fats that can increase risk of stroke.
"I don't think this study means to the public you should run out and start eating burgers and red meat," said Dr. Ralph Sacco, chair of neurology at the University of Miami's Miller School of Medicine. "Focusing on lean protein consumption and/or even vegetable protein is important."
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Kindergarten classroom walls are typically covered with cheerful, busy artwork. Colorful charts, calendars, drawings and handwriting pages can nearly take over all the open space. But a new study questions whether all the sensory effect might be detrimental to young children’s ability to focus and learn the lessons being taught.
For a study at Carnegie Mellon University, 24 kindergartners were given six introductory science lessons on unfamiliar topics. They were taught half the lessons in a heavily decorated classroom and half in a sparsely decorated classroom. The students learned in both classrooms but learned more in the classrooms with fewer decorations.
According to lead author Anna V. Fisher, the research showed that a classroom’s visual environment can affect how much young children learn, but more research is needed to measure the full effect.
“I would suggest that instead of removing all decorations, teachers should consider whether some of their visual displays may be distracting to young children,” Fisher said.
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Scientists used to think only humans feel regret, but some animals may also regret bad choices.
"Regret is the recognition that you made a mistake, that if you had done something else, you would have been better off," said study author David Redish, Ph.D., a professor of neuroscience in the University of Minnesota Department of Neuroscience.
Researchers at the University of Minnesota Academic Health Center created an experiment called “restaurant row” -- four different food stops a rat could make. At each entrance, a tone indicated how long the rat would have to wait to receive food. A rat could either stay, or choose to try something else. "If the line is too long at the Chinese food restaurant, then you give up and go to the Indian food restaurant across the street." Redish said.
The rats had preferences for specific foods and would only wait a certain amount of time to get it. The researchers decided to see what would happen if the rats skipped a ‘good deal’ only to discover a ‘bad deal’ at the next place. To the researchers' surprise, when the rats made a bad choice they stopped and looked back. This, they surmised, suggested they regretted their decision.
The researchers then used imaging to study the brain activity of the rats and found that when a rat made a mistake, the orbitofrontal cortex of the brain–the part of the brain believed to process regret in humans–was activated.
Although rats' regret response was similar to humans', the UofM researchers said they were unsure whether rats have human-like reflection about decisions. But they said the study shows that animal models may be used to better understand certain human behaviors.
A single-letter change in the genetic code is enough to generate blond hair in humans, in dramatic contrast to our dark-haired ancestors. A new analysis by Howard Hughes Medical Institute scientists has pinpointed that change, which is common in the genomes of Northern Europeans, and shown how it fine-tunes the regulation of an essential gene.
"This particular genetic variation in humans is associated with blond hair, but it isn't associated with eye color or other pigmentation traits," says David Kingsley, an HHMI investigator at Stanford University who led the study. "The specificity of the switch shows exactly how independent color changes can be encoded to produce specific traits in humans." Kingsley and his colleagues published their findings in the journal Nature Genetics.
Kingsley says a handful of genes likely determine hair color in humans, however, the precise molecular basis of the trait remains poorly understood. "I think you will see a lot more of this type of study in the future, leading to a much better understanding of both the molecular basis of human diversity and of the susceptibility or resistance to many common diseases," Kingsley said.
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