Genes Play Key Role in Elderly Fracture Risk

September 13, 2005 08:41:32 PM PST

Researchers in Sweden studied more than 6,000 elderly twins who suffered fractures. More than half of the fractures resulted from osteoporosis.

The study found that variations in each person's genes accounted for less than 20 percent of the difference in overall age-adjusted fracture risk. The influence of genetic factors was much greater for a first hip fracture among people younger than 69 years old, and for those between the ages of 69 and 79 than for people older than 79, according to researchers at Uppsala University Hospital.

"We conclude that the genetic influence on susceptibility to fractures is dependent on type of fracture and age at fracture event," the study authors wrote in the Sept. 12 issue of the Archives of Internal Medicine.

The findings suggest that genetics may be more important to osteoporosis and fracture risk than previously understood, "especially for early-occurring osteoporotic fractures," the Swedish team note.

But while more investigation into the genetic underpinnings of bone health is warranted, "fracture-prevention efforts at older ages should [still] be focused on lifestyle habits," they say.

More information

The U.S. National Institute on Aging offers advice on how to prevent falls and fractures.

It All Adds Up for Kindergarteners

Math and language go hand-in-hand. You can't count without words for numbers, right?

Wrong. Research shows some animals have the ability to calculate quantities, and now a new study suggests that young children do, too, even if they don't know it.

Preschoolers with no conscious understanding of arithmetic were still able to add two numbers and compare the total to another number. They weren't as accurate as a calculator, but that's not the point, said study co-author Elizabeth Spelke, a professor of psychology at Harvard University.

"What we've shown in the children is an ability to get to approximately the right answer," she said. And that, she added, gives educators more insight into the "building blocks" of mathematical knowledge.

On a larger scale, better understanding of the mathematical abilities of children and animals will help researchers comprehend the differences -- and similarities -- between Homo sapiens and other species, said Randy Gallistel, co-director of the Center for Cognitive Science at Rutgers University in Piscataway, N.J.

Many animals have to make basic mathematical calculations to determine which region has more food, he said. And Gallistel's own studies with mice have found they can differentiate between different numbers of light flashes.

In the new study, Spelke and her colleagues turned to 5-year-old humans. They recruited 16 children who were tested to make sure they were "clueless" about the workings of addition, she said.

The children then took part in several experiments to determine if they could, in fact, add numbers, even if they hadn't been taught how. In one experiment, for example, children looked at two computer screens full of dots, and then listened to a series of tones. Then they were asked which group of items -- the dots or the tones -- was larger.

Two thirds of the time -- more than chance would predict -- the children correctly chose which group was bigger. They also did well on tests that asked them to look at dots of various sizes.

In essence, the kids "were able to cluster numbers without any words or symbols," and without having been taught how to add, Spelke said. "We think it is innate. It doesn't seem to depend on language or instruction."

The findings appear in the Sept. 12-16 early edition of the Proceedings of the National Academy of Sciences.

The next step, Spelke said, is to determine whether preschoolers have a built-in ability to handle subtraction.

What does it all mean? The findings could poke a hole in the philosophical assumption that "number is an abstraction made only possible by language, something only intellectual 'giants' like ourselves can understand," Gallistel said. "Most philosophers have taken it as practically self-evident that arithmetic reasoning rests on a language foundation."

Also in this week's issue of the Proceedings of the National Academy of Sciences, French researchers report that some children with learning disabilities may have an especially hard time tuning out background noises, making it harder for them to learn. Some of the children seem to have difficulty picking up consonant sounds like "b" and "p" in noisy situations, reported scientists at the Universite de Provence in Marseille.

More information

The Ambulatory Pediatric Association has advice on building your child's preschool and school skills.