FRIDAY, Feb. 26 (HealthDay News) -- Genes that influence tooth development in the first year of life have been identified by British and Finnish researchers.

They analyzed the genetic code of 6,000 people in Finland and Britain who took part in studies that tracked them from their mother's early pregnancy until adulthood. The scientists pinpointed five genes associated with the time of the appearance of the first tooth and the number of teeth by age 1. In addition, one of the genes was associated with a 35 percent increased risk of requiring orthodontic treatment by age 30.

Identification of genes that play a role in tooth development and growth may lead to innovations in the early treatment and prevention of dental problems, the researchers said.

They also noted that teeth and other organs have common growth and development pathways during early development. Some of the genes identified in this study have previously been found to be associated with the development of the skull, jaws, ears, fingers, toes and heart.

"The discoveries of genetic and environmental determinants of human development will help us to understand the development of many disorders which appear later in life. We hope also that these discoveries will increase knowledge about why fetal growth seems to be such an important factor in the development of many chronic diseases," study leader Marjo-Riitta Jarvelin, of the School of Public Health at Imperial College London, said in a news release.

The study appears in the Feb. 26 issue of the journal PLoS Genetics.

More information

The Nemours Foundation has more about mouth and teeth development.

WEDNESDAY, Feb. 24 (HealthDay News) -- Almost one-third of young adults in their 20s lacked health insurance in the United States in 2008, new statistics show.

The problem was more pronounced among men 20 to 29 years of age, 35 percent of whom went without coverage for medical care. As a result, these uninsured 20-somethings are less likely to visit a doctor on a regular basis, less likely to fill prescriptions and more likely to arrive at the emergency room.

"The highest uninsured rate is among people in their 20s and even though this is a relatively healthy group, they do need some access to health care," said Robin A. Cohen, lead author of a data brief just released by the National Center for Health Statistics, part of the U.S. Centers for Disease Control and Prevention.

"If you don't have insurance you're less likely to have a usual source of medical care. You're also less likely to have visited a doctor and you're more likely to have an unmet medical need," Cohen added.

"This is a problem that's existed for some time, and it's worsened over the last few years," said Sara Collins, vice president of the Affordable Health Insurance Program at The Commonwealth Fund in New York City. "We have an employer-based health insurance system so to the extent that you are without strong connections to that system when you have a transitional period, you're going to be at risk of losing your health insurance coverage."

And people in their 20s generally are in transition, moving from home where they could be on their parents' plan, to college where they could be on a college plan or to the workforce, where they may be on no plan.

And children who had been covered under Medicaid aren't likely to be eligible for that program when they turn 19, Collins added.

Based on data collected from more than 13,000 adults aged 20 to 29, the researchers discovered that:

• U.S. adults in their 20s were almost twice as likely as adults aged 30 to 64 to go without health coverage (31 percent versus 17 percent).
• Seventy percent of adults in their 20s had a "usual source" of medical care, although only 44 percent of young adults without insurance had such a source.
• Women were more likely to have regular health-care practitioners than young men: 91 percent of women among those with private coverage versus 70 percent of men in the same category. Fifty percent of women without coverage had a regular doctor, compared with 39 percent of men in this category.
• Adults in this age group without insurance were four times as likely as those with private insurance and twice as likely as those with Medicaid to have "unmet medical need."
• One-quarter of uninsured people in this age group did not fill a needed prescription, compared with 6 percent of those with private insurance and 12 percent of those on Medicaid. Women were more likely than men to have an unmet need in this area.
• About 10 percent of adults in their 20s reported at least two visits to an emergency room in the past year, with women twice as likely to have visited compared with men (12 percent versus 6 percent).

Greg Scandlen, founder of Consumers for Health Care Choices, pointed out that the situation has probably worsened since 2008 as a result of the deteriorating economy, but that there was little new in the idea that many 20-somethings lack health insurance.

"It's always been young adults who are most likely to be uninsured, and most of the people who are employed do have workers' comp and do have auto insurance so they are actually covered for things most likely to happen to them in that age group," he said.

"The implication here is that everyone should see a doctor once a year. I think that's crazy. The whole notion of an annual physical exam is just a waste of money," Scandlen said. "Women are far more likely to see a doctor more regularly because of ob/gyn issues, but the fact that young men in their 20s don't see a doctor doesn't bother me at all."

More information

The U.S. government has more on the current health reform plan.

WEDNESDAY, Feb. 24 (HealthDay News) -- Naps play an important role in infant learning by helping children's developing brains retain information, a new study has found.

Researchers at the University of Arizona in Tucson found that infants who have daytime naps are more likely to exhibit an advanced level of learning called abstraction -- the ability to detect a general pattern contained in new information.

In this study of 48 infants, phrases from an artificial language were repeatedly played to the 15-month-olds until they became familiar with them. Follow-up tests showed that infants who slept within four to eight hours after hearing the phrases showed evidence of abstract learning. This wasn't the case for infants who didn't have a nap within that timeframe.

"What we know is that infants have mostly REM sleep, given the type of sleep they have, given how their brains are developed at that point. And they have to get some of that sleep within a reasonable amount of time after inputting information in order to be able to do abstracting work on it. If they don't sleep within four to eight hours, they probably just lose the entire thing," lead researcher Lynn Nadel, a professor in the psychology department, said in a university news release.

The findings were presented Feb. 21 at the American Association for the Advancement of Science annual meeting, in San Diego.

While it's important to provide infants and young children with the kind of mental stimulation that comes from talking and reading to them, it's also crucial to ensure this is done as part of a well-regulated daily cycle that includes adequate sleep, Nadel said.

More information

Zero to Three has more about brain development.

TUESDAY, Feb. 16 (HealthDay News) -- Cell phones, televisions and computer games aren't giving teenagers headaches, researchers say, but listening to one or two hours of music daily may make their heads throb.

The authors of a study published online Feb. 9 in the journal BMC Neurology looked at a group of 13- to 17-year olds -- 489 who said they had headaches and 536 who didn't. No association was seen between electronic media devices and headaches.

"Excessive use of electronic media is often reported to be associated with long-lasting adverse effects on health, like obesity or lack of regular exercise, or unspecific symptoms like tiredness, stress, concentration difficulties and sleep disturbances," said study co-author Astrid Milde-Busch of Ludwig-Maximilians-University Munich in Germany. "Studies into the occurrence of headaches have had mixed results and for some types of media, in particular computer games, are completely lacking".

As for a link between music-listening and headaches, it's not clear if listening to music causes the headaches or is something teens do to soothe themselves when they get a headache.

More information

For more about headaches, try the U.S. National Library of Medicine.