Body & Brain

When the brain learns to feel pain, kids’ effect on paternal testosterone and more in this week’s news

Baby’s first pain
Babies’ brains start distinguishing a painful prick from a harmless touch just before they’re born, a new study shows. By monitoring electrical activity of premature babies’ brains, researchers found that infants born before about 35 weeks of gestation didn’t distinguish between a painful heel prick (required for a blood sample) and a painless touch. In contrast, the brains of babies born on schedule showed pain-specific responses after a heel prick. The results may help doctors better understand and treat pain in babies, Lorenzo Fabrizi of the University College London and colleagues report September 27 in Current Biology.—Laura Sanders

Dads have lower testosterone
Fatherhood may put a damper on masculine hormones. Scientists knew that fathers have lower testosterone levels than childless men, but it wasn’t clear which came first. Lee Gettler and Christopher Kuzawa of Northwestern University in Evanston, Ill., and their colleagues tried to solve that mystery by following a group of 624 men in the Philippines. Men with high testosterone levels at the beginning of the study were more likely to find a partner and father children. But those dads’ testosterone levels dipped more with age than single non-fathers’ levels did, the researchers report September 12 in the Proceedings of the National Academy of Sciences. The dip may lead to greater nurturing for children and better health for dads. —Tina Hesman Saey

Odd valve means aorta risk
About 1.3 percent of people have an abnormal aortic heart valve, a defect that might heighten their risk of tearing the aorta, researchers report in the Sept. 14 Journal of the American Medical Association. The defective valve has two flaps instead of the normal three, and while it has been considered dangerous, the risk hadn’t been measured in a long-term study. Researchers at the Mayo Clinic in Rochester, Minn., and Massachusetts General Hospital in Boston analyzed 16 years of health records for 416 patients who had the abnormal valve. This group was eight times as likely as the general population during that time to tear the aorta — the huge artery leading out of the heart — suggesting these patients should be monitored carefully.  —Nathan Seppa

A quarter of North Americans get COPD
The lifetime risk of developing emphysema or another form of chronic obstructive pulmonary disease among North Americans is more than one in four, a team of Toronto-based researchers reported in the Sept. 10 Lancet. The scientists tapped into a database of adults in Ontario — a diverse, multi-ethnic population — who were free of COPD as of 1996 and monitored them for 14 years. At that point the researchers calculated that the risk of being diagnosed with COPD by age 80 was 27.6 percent. The risk was slightly higher for men than women, was more common in rural dwellers than in urban folks and greater in low socioeconomic groups than among high earners. —Nathan Seppa

Kidney cancer tied to NSAIDs
Tapping into large medical databases, researchers at Harvard University have found that taking nonsteroidal anti-inflammatory drugs may hike a person’s risk of kidney cancer. The researchers used questionnaires to get a “snapshot” of medication use among nearly 50,000 men and more than 77,000 women starting in the 1980s or 1990s. About 20 years later the NSAID users were slightly more likely to develop kidney cancer, but not if they used the drugs for less than four years and only marginally if they used them for four to 10 years. Those taking NSAIDs for at least 10 years had roughly two to five times the risk as nonusers, the scientists reported in the Sept. 12 Archives of Internal Medicine. Kidney cancer strikes about 10 in 100,000 women and about 20 in 100,000 men annually. Taking aspirin or acetaminophen didn’t appear to impart any added kidney cancer risk. —Nathan Seppa

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