Body & Brain

Cancer treatment raises stroke risk, plus ankle-powered sprints, irregular heartbeats and more in this week’s news

Heart arrhythmia signals risk for women Healthy middle-aged women who experience atrial fibrillation, the most common kind of irregular heartbeat, face a heightened risk of death. Of nearly 35,000 women over age 45, 1,011 developed atrial fibrillation during a 15-year study by a U.S.-Swiss research team. Overall, 1,602 women in the study died during that time, including 63 who had developed atrial fibrillation at some point, the researchers report in the May 25 Journal of the American Medical Association . After accounting for cardiac risk factors and other differences among the women, the researchers calculated that those with the irregular heartbeat were 70 percent more likely to die from any cause than those without it, and even more likely to die of heart problems. — Nathan Seppa Weight gain boosts pregnancy diabetes risk Women who put on extra pounds between pregnancies multiply their risk of developing gestational diabetes, researchers report in the June Obstetrics & Gynecology . Researchers at Kaiser Permanente of Northern California in Oakland analyzed medical records from more than 22,000 women who had had multiple births. About 3.5 percent of women who didn’t have gestational diabetes during their first pregnancy developed it in the second. Putting on 6 to 12 pounds (for a 5’4” woman) increased this risk by 70 percent, and adding more weight doubled or tripled it, depending on how much was added. Losing weight between pregnancies lowered the risk of gestational diabetes in the second pregnancy only for overweight women. — Nathan Seppa Vessel-damaging brain radiation High doses of cancer-fighting radiation to the brain are associated with heightened risk of dying from a brain hemorrhage or stroke. Among 4,227 survivors of childhood cancer, the risk of later dying from a brain hemorrhage or stroke was more than three times higher for people who had received brain radiation as children, researchers in France and England report in the May issue of Brain . In particular, the dose delivered to a particular part of the brain, the prepontine cistern, which is close to an important blood vessel supply route, tracked with heightened risk. Chemotherapy had no such association. High levels of radiation might damage the blood vessels in the brain, leading to the heightened risk. — Laura Sanders Telling neurons who’s boss There’s no more excuse for a wandering eye. Trained monkeys can bring individual brain cells involved in vision under their control, Robert Schafer and Tirin Moore at Stanford University report online May 26 in Science . Such control may make the monkeys better at paying attention, too. The researchers gave two monkey subjects treats for turning the activity level of vision neurons in the front of the brain up or down in response to training cues. When the monkeys sparked these brain cells up, the tree-climbers were better able to spot targets during vision tests. Such training may help people suffering from attention disorders rein in their brains’ scattered focus, the team says. — Daniel Strain Fleeing physics Physics is usually the last thing a person thinks of while fleeing an angry bear. A new study, however, illustrates how the human body redistributes its power when going from a leisurely stroll to a run-for-your-life sprint. Runners power their strides less with their hips and more with their ankles than walkers do, researchers from North Carolina report online May 25 in the Journal of the Royal Society Interface . People get 40 percent to 50 percent of their power from the hip while walking but as little as 32 percent during running. The switch to ankle power seems to improve gait efficiency since ankle muscles are much more springy, the team says. — Daniel Strain

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