Feature

Health & Science

A new way to keep older minds sharp; The healthiest fruit; Bacteria that make you thin; The upside of small testicles

A new way to keep older minds sharp
To stay mentally sharp, seniors may want to swap their crossword puzzles for a video game controller. New research at the University of California, San Francisco, found that learning to multitask in a fast-paced environment significantly improved the cognitive abilities of older adults—and the improvement was long-lasting. Researchers asked volunteers ages 60 to 85 to play a video game called NeuroRacer, designed to train them to multitask effectively. In the game, players are required to steer a car down a winding road; after a while, signs begin to pop up, and the volunteers have to identify them while continuing to drive. When the volunteers first played the game, their driving skills fell by 64 percent when the signs appeared; by comparison, people in their 20s saw only a 26 percent drop in performance. But after a month of playing the game three times a week, the older adults handled the appearance of the signs better than untrained young people. What’s more, they scored higher on tests of short-term memory and long-term focus after training than they had before, and brain scans showed they had increased activity in regions linked to attention. “I feel like my brain is working better,” Ann Linsley, 65, a participant in the study, told The Wall Street Journal. The study “shows you can take older people who aren’t functioning well and make them cognitively younger through this training,” said Earl K. Miller, a neuroscientist at the Massachusetts Institute of Technology. “It’s a very big deal.”

The healthiest fruit
All fruit isn’t created equal when it comes to preventing diabetes. A Harvard University study that tracked the diets of more than 185,000 people over 12 years shows that eating strawberries, oranges, peaches, plums, and apricots has no impact on a person’s likelihood of developing type 2 diabetes. But grapes, apples, grapefruit, and blueberries do help ward off the disease. Blueberries had the greatest effect on diabetes risk: Eating between one and three servings a month decreased risk by 11 percent; eating five servings a week decreased it by 26 percent. But the benefits of certain fruits don’t extend to juices made from those fruits. The study found that drinking a single serving of juice per day increases the risk of diabetes by 21 percent. “During juicing processes, some phytochemicals and dietary fiber are lost,” study author Qi Sun tells NationalGeographic.com. The phytochemicals include antioxidants that may help the body break down glucose, while fiber slows absorption of sugars. Many juices also contain added sugars, which can promote diabetic changes in the body.

Bacteria that make you thin
The species of bacteria that dominate our guts may strongly affect whether we’re thin or fat, The New York Times reports. Researchers at Washington University collected samples of gut bacteria from pairs of twins in which one was obese and the other thin. Then they transplanted the bacteria into mice. The mice that received the bacteria from the obese twins became obese; the mice that received the bacteria from the lean twins remained lean. The result is “the clearest evidence to date that gut bacteria can help cause obesity,” says Michael Fischbach of the University of California, San Francisco. The experiment also showed that what we eat helps determine what kinds of microbes colonize us. When the gut bacteria of thin mice were introduced to fat mice, the fat mice lost weight—but only if the fat mice were on a low-fat diet. If they were eating a high-fat diet, the bacteria from the thin mice failed to take hold. Could fecal transplants from thin to obese people—helped along by dietary changes—be the future of weight loss? “I have little doubt that that will be the next thing that happens,” Fischbach says.

The upside of small testicles
The smaller a man’s testicles, the more attentive a father he’s likely to be. That’s the conclusion of a study that surveyed 70 men who had a child between the ages of 1 and 2. Researchers found that the smaller the men’s family jewels, the more likely their wives were to report that they were involved parents—spending a lot of time feeding, diapering, and playing with their toddlers. Brain scans also found that these men found it highly rewarding just to look at their kids’ pictures. Researchers say large testes—and a corresponding higher level of testosterone and sperm production—may encourage their owners to father as many children as possible, which gives them a certain evolutionary advantage. Men with smaller testicles may compensate by taking more care with the fewer children they do produce. But study author James Rilling, an anthropologist at Emory University, tells CBSNews.com, “It could also be that when men become more involved as caregivers, their testes shrink.” Previous research has also shown that a man’s testosterone levels drop if he engages in frequent child care.

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