Health & Science

The Alzheimer’s-resistant personality

Virtue, goes the old saying, is its own reward. But a new study has found that self-disciplined, highly organized people get a bonus: They’re less susceptible to Alzheimer’s disease. The study, which looked at how personality and behavior may affect the incidence of Alzheimer’s, began with a personality survey of 997 healthy but elderly Catholic nuns and priests in the Chicago area. Researchers then tracked their mental states between the years 1994 and 2006. Nuns and priests who received a high score for “conscientiousness’’ were 89 percent less likely to develop Alzheimer’s-type dementia than their less-meticulous peers. “These are people who control impulses, and tend to follow norms and rules,” study author Robert Wilson tells New Scientist. Curiously, autopsies on the subjects who died during the study found no reduced incidence of Alzheimer’s brain plaques among those with conscientious personalities; in fact, researchers found that the brains of the various personality types showed equal rates of tangled proteins associated with the disease. Wilson suggests that the difference may be in the way that disciplined people use their brains—they’re more likely to think with their frontal lobes. Using this part of the brain, which is responsible for decision-making and planning, may make one less vulnerable to impaired thinking caused by lesions in other areas, he says.

A year of pampering, and then death

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Children whom the Inca sacrificed to the gods were pampered and fattened up for a year before meeting their doom. An analysis of hair from four 16th-century Inca mummies, who had been children ages 6 through 15, found that they’d transitioned from a peasant’s diet of vegetables and grains to a richer diet of maize and llama meat, foods that were reserved for the elites of Inca society. In the case of one of the children, the famous “Llullaillaco Maiden”—whose 15-year-old body was well preserved in the cold, dry climate of the mountaintop on which she was sacrificed—death was preceded by a prolonged period of soft, pampered living. We can only guess at how the children were sacrificed, researcher Timothy Taylor tells Scientific American. “It looks to us as though the children were led up to the summit shrine, drugged, and then left to succumb to exposure.”

Cats may be hazardous to health

An allergy to cats has triggered almost a third of all the asthma cases in the U.S., says a new study by the National Institute of Environmental Health Sciences. Of those who have been diagnosed with the chronic lung disease, in which airways become constricted, 56.3 percent can blame the condition on allergies. Cat dander is by far the most common allergen, triggering 29.3 percent of all asthma cases, followed by the fungus Alternaria, at 21.1 percent, and white oak trees, at 20.9 percent. “Sensitization to cats appears to be a strong risk factor for asthma,” senior investigator Darryl Zeldin tells LiveScience. More than 20 million Americans have asthma, and 4,000 people die during asthma attacks each year.

The saber-tooth’s weak bite

The saber-toothed tiger’s teeth may have looked fearsome, but his bite was fairly wimpy, says a new analysis of the prehistoric cat’s anatomy. The jaw of the species Smilodon fatalis had just a third of the biting power of a modern lion’s, meaning that the saber-toothed tiger would have been unable to kill its prey by clamping down on its throat. Instead, paleontologists say, Smilodon fatalis used its heavily muscled, 450-pound body to wrestle its victim to the ground before piercing the animal’s carotid artery or spine with its 7-inch talons. “People think of the saber-toothed cat as a lion with big teeth,” researcher Colin McHenry tells the Associated Press. “But if you had actually seen it, you’d have thought it was a bear with big teeth.” The saber-tooth prowled the Americas for about 3 million years, becoming extinct about 10,000 years ago.

The fine art of marital dispute

Women who swallow their anger during marital disputes are more likely to die of heart disease than women who speak their minds, a new study shows. Unfortunately, when women do argue in a controlling, domineering way instead of seeking some consensus, it’s their husbands’ coronary health that is damaged. The findings emerged from a University of Utah study of 150 married couples, who were videotaped while discussing sensitive subjects such as how they managed money or household chores. When men dominated the conversation and made cutting remarks while the wives sat mostly silent, researchers found, subsequent analysis of the women’s hearts found high levels of coronary calcification—a sign of heart disease. Men, on the other hand, suffered no ill effects from “self-silencing,” but showed more evidence of heart disease if arguments with their wives turned into an open battle for control, instead of a more cooperative discussion of how to make things better. “Disagreements in a marriage are inevitable, but it’s how you conduct yourself,” researcher Timothy W. Smith told The New York Times. “Can you do it in a way that gets your concerns addressed but without doing damage at the same time? That’s not an easy mark to hit.”

Health scare of the week

The amoeba that eats your brain

A rare killer amoeba that infects swimmers and eats their brain tissues appears to be on the increase as a result of global warming, says the Los Angeles Times. So far this year, six people have died in the U.S. after the amoeba, called Naegleria fowleri, entered their noses while they were swimming in lakes and ponds, and made its way to their brains. In past years, only about two people died of the infection every year. Michael Beach, a waterborne disease specialist with the Centers for Disease Control and Prevention, says the parasite is likely to be more prevalent in a warmer climate. “This is a heat-loving amoeba,” he tells the Associated Press. “In future decades, as temperatures rise, we’d expect to see more cases.” The CDC says that people can avoid infection by staying away from the amoeba’s favorite environments: warm bodies of fresh water such as lakes, ponds, unchlorinated swimming pools, and hot springs.