Health & Science

Why trauma hurts some more than others

Scientists have come up with an unexpected explanation for why some of us can walk away from a frightening experience unscathed, while others are traumatized. Researchers performed DNA tests on 900 people and found a strong link between mutations in a gene that regulates stress and incidence of post-traumatic stress disorder, or PTSD. This faulty gene led to PTSD, interviews with the subjects showed, especially if the person had been the victim of child abuse or experienced some other severe trauma at a young age. The study, in the Journal of the American Medical Association, found that childhood trauma appears to make brain cells in children more sensitive to stress hormones throughout their lives. The findings are of special interest to mental-health professionals who are treating tens of thousands of traumatized veterans from the wars in Iraq and Afghanistan. The results, Dr. Thomas Insel tells the Associated Press, could help explain why two soldiers who witness the carnage of a roadside bomb can go on to have such different reactions. One might later develop paralyzing PTSD symptoms such as nightmares and acute anxiety, Insel said, while the other experiences it “as a bad day, but goes back and is able to function.”

The biggest loser: Zoo edition

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America’s obesity epidemic is spreading to the nation’s zoos. Veterinary nutritionists report that gorillas, lions, and other zoo dwellers have been packing on the pounds, prompting many zoos to bring in diet and fitness experts to help them create a healthier lifestyle for their captives. Obesity is a problem in zoos because, like humans, animals “like sugary, high-fat food,” nutritionist Jennifer Watts tells Discovery News, “and they’re not moving as much as they are genetically programmed to.” Zoo trainers who have traditionally used treats such molasses and granola bars to coax or reward animals are starting to rely instead on low-calorie offerings such as sugar-free Jell-O and alfalfa biscuits. Being overweight can be just as unhealthy for animals as it is for humans. Chicago’s Brookfield Zoo recently learned that its prized 74-year-old cockatoo, Cookie, was developing osteoporosis. “For about 40 years all he ate was seeds,” Watts said, though his natural habitat would have offered more healthful choices such as beetles and fruit. “The best we can do here at the zoo is mimic those nutrients.”

The secret of alligators’ stealth

Alligators are deadly predators not merely because of their strong jaws but because of their stealth: They are adept at sneaking up on unsuspecting prey. But scientists have been mystified about how such large animals, despite their lack of fins and flippers, are able to glide through the water and hardly make a sound. The answer, new research concludes, has to do with the unusual way alligators can manipulate their lungs. According to the University of Utah study, alligators use special pelvic and abdominal muscles to shift the position of their lungs and change their center of buoyancy—forcing the lungs toward the tail when they dive, toward the head when they surface, and sideways to roll. “It gives the animal a way to change trajectory,” researcher T.J. Uriona tells the Los Angeles Times, noting that the subtle shifting does not require any quick movements. “It allows them to quietly change how they are positioned in the water so they can strike.”

The arthritis diet

A new study of people with rheumatoid arthritis has found that a vegan, gluten-free diet might offer relief. Rheumatoid arthritis is a dysfunction of the immune system in which cells attack the lining of the joints, causing pain, inflammation, and restricted movement. The cause of the disease is unknown, and treatment options are limited. But a small Swedish study of 30 rheumatoid arthritis sufferers found that a diet free of animal products and wheat offered some relief. Though researchers could not explain why the diet helped, they found that patients in the study were experiencing less swelling and inflammation, while blood tests showed lower levels of LDL (bad) cholesterol. “I think it is a quite unexpected and interesting finding,” study leader Johan Frostegard tells the London Guardian. “The effects on the immune system are quite new.”

An epidemic of mental decline

More than 5 million elderly Americans have a hard time remembering things, sorting through daily decisions, and sometimes even knowing what day it is, a new federal study found. Using detailed evaluations of a nationally representative sample of 856 people ages 71 and up, the study found that 22 percent, or 5.4 million people, are experiencing a decline in their mental faculties. Combined with a previous estimate that 3.4 million Americans have Alzheimer’s or other types of dementia, it now appears that more than one-third of the nation’s elderly have some diminished mental function. “This is important because the number of people with cognitive impairment is likely to increase significantly as the baby boomers age,” study leader Brenda Plassman tells The Washington Post. The extent of the problem surprised experts. “Five million people is a lot,” said Richard Suzman of the National Institute on Aging. “This is confirmation that this is a very big problem.” Nearly a quarter of those with declining mental function had a chronic medical condition, such as diabetes or heart disease, which appeared to be the underlying cause of their cognitive problems.