TUESDAY, Feb. 26 (HealthDay News) -- For parents of emotionally combative teens, new research offers a powerful biological reason for all the family feuding -- adolescent brain size.

A team of Australian scientists has found that when key regions of the brain known for controlling emotions are bigger, boys and girls tend to be more aggressive and more persistent during their fights with Mom and Dad.

"This is a bit of a unique study," said study author Nicholas Allen, an associate professor with the Orygen Research Centre at the University of Melbourne. "Because we've shown for the first time that in terms of aggression -- not physical, but being argumentative and unfriendly -- some of the differences in the way teen kids interact with parents are biologically based. The adolescent is developing, their brain is developing, and there's a link between the two."

The finding was published in this week's online issue of the Proceedings of the National Academy of Sciences.

The authors first videotaped 20-minute "problem-solving" discussions with 137 Australian teens between the ages of 11 and 14 and one of their parents. The interactions were spurred on by the introduction of provocative family issues, and analyzed for language and emotional content.

Following MRI scans of the teens' brains, Allen and his colleagues observed that children with large amygdala regions were more likely to engage in longer and more aggressive arguments with their parents.

They also reported that male -- but not female -- teens possessing an atypical unevenness in the size of two left brain regions -- the anterior cingulate cortex and the orbitofrontal cortex -- were also more likely to maintain aggressive behavior, as well as whiny and anxiety-laced behavior (collectively referred to as dysphoria).

In an attempt to explain gender variations in left-right brain asymmetry, Allen noted that left- and right-side brain regions are normally different in size, but that such differences are typically bigger in boys than girls.

"We think that when the difference is actually less than it usually is among boys -- but not girls -- this contributes to some mental health problems and, perhaps, aggressiveness," he said.

"But there's relatively little research -- almost none -- that shows a relationship between brain structure and actual behavior," Allen added. "So we can't say what the direction of causation is. It could be that environment has influenced teen brain structure. Or that brain structure is influencing their relationship behavior with the parents. Or it could be both. More and more, I think we are realizing that it's not a matter of a simple equation. It's a question of an interaction of both environment and biology. But we don't yet know how these two areas interact."

Elliott Albers, director of the Center for Behavioral Neuroscience at Georgia State University in Atlanta, agreed that many key questions remain.

"This study is very interesting and consistent with prior animal studies which support the concept that there are changes in limbic structures that can potentially relate to aggression," he said.

"However, we still don't know if conflict causes physical changes -- whether the social experiences of boys and girls cause different changes in their limbic system that can affect aggression -- or whether it's the other way around. Frankly, we still don't know much about what causes the neuroscience of aggression," Albers said.

More information

For more on the adolescent brain, visit Bryn Mawr College  .

MONDAY, Feb. 25 (HealthDay News) -- Exposure to viral infection -- especially herpes viruses -- may be associated with high blood pressure during pregnancy and preterm birth, Australian researchers report.

The findings -- the first of their kind -- are a major advance in learning more about the cause of hypertension in pregnancy, according to the authors of the study, which was published in the British Journal of Obstetrics & Gynaecology.

Over 10 years, researchers from Adelaide's Women & Children's Hospital and the University of Adelaide detected the presence of viral nucleic acid in heel-prick blood samples from 1,326 newborns -- more than 400 of whom were diagnosed with cerebral palsy.

"This is an exciting finding and further studies are now required to look at the link between viral exposure in pregnancy and genetic susceptibility to adverse pregnancy outcomes, such as high blood pressure, premature delivery and cerebral palsy," research group leader Alastair MacLennan, a professor in the Department of Obstetrics and Gynaecology, said in a prepared statement.

High blood pressure occurs in up to 10 percent of first pregnancies in the United States and other developed nations. It's a common cause of death among pregnant women in developing countries.

Previously, the Adelaide group identified a link between viral infection in pregnancy, genetic mutations in genes controlling inflammatory and blood clotting processes, and the development of cerebral palsy. They also found an association between several hereditary gene mutations and changes in inflammatory proteins that may cause dysfunction and constriction of blood vessels in the placenta and brain, resulting in increased blood pressure during pregnancy.

"We are just beginning to understand the interaction and importance of exposure to viruses and genetic susceptibility to infection both in pregnancy and the newborn," Paul Goldwater, an associate professor and the research team's virologist, said in a prepared statement.

More information

The American Academy of Family Physicians has more about high blood pressure during pregnancy  .

WEDNESDAY, Feb. 20 (HealthDay News) -- Reducing children's salt intake may lower their consumption of sugar-sweetened soft drinks and reduce their risk of obesity, high blood pressure and other health problems later in life, British researchers say.

Scientists at St. George's University of London analyzed data on more than 1,600 boys and girls, aged 4 to 18, in Great Britain, and found that those who ate a lower-salt diet drank less fluid. The researchers estimated that cutting 1 gram of salt from a child's daily diet would reduce the child's overall fluid intake by 100 grams per day.

The data analysis also revealed that children who ate a lower-salt diet also drank fewer sugar-sweetened soft drinks. The researchers calculated that reducing a child's salt intake by 1 gram per day would reduce the child's sugar-sweetened soft drink consumption by 27 grams per day.

"If children aged 4 to 18 years cut their salt intake by half (i.e., an average reduction of 3 grams a day), there would be a decrease of approximately two sugar-sweetened soft drinks per week per child, so each child would decrease calorie intake by almost 250 kcal per week," Dr. He said in a prepared statement.

Not only would reducing salt intake lower blood pressure in children, but it could also play a role in helping to reduce obesity, said He.

The study was published in the current issue of Hypertension.

In a related editorial in the same issue of the journal, Dr. Myron H. Weinberger of the Indiana University Medical Center, wrote that reducing children's intake of salt and sweetened beverages, combined with increased physical activity, "could go a long way in reducing the present scourge of cardiovascular disease in our industrialized society. Obviously, each step in this progression requires further definition and confirmation. This presents a formidable challenge as we move into the 21st century."

More information

The Nemours Foundation has more about overweight and obesity in children  .

MONDAY, Feb. 18 (HealthDay News) -- Antibiotics don't significantly reduce fluid buildup in young children with inner ear infections, a new analysis shows.

Whether such drugs work in this regard has been a matter of conjecture, with one recent study suggesting a benefit in children aged 2 and under. So, Dutch researchers did a meta-analysis of several previously published studies and found the results don't support the use of antibiotics for the fluid buildup that can accompany inner ear infections.

"Due to the marginal effect and the known negative effects of prescribing antibiotics, such as the development of antibiotic resistance and side effects, we do not recommend prescribing antibiotics to prevent middle ear effusion," said lead researcher Maroeska M. Rovers, from the Julius Center for Health Sciences and Primary Care at the University Medical Center Utrecht in The Netherlands.

Ear infections are very common among infants and children. They can lead to fluid buildup in the ear, which is known as otitis media with effusion. This buildup can result in hearing loss, which can affect language development, cognitive development, behavior and quality of life, according to the researchers.

The report was published in the February issue of the Archives of Otolaryngology-Head & Neck Surgery.

In the study, Rovers' team collected data on 1,328 children aged 6 months to 12 years with acute middle ear infection. These children had participated in five studies that compared treating ear infections with antibiotics to a placebo or no treatment at all.

Among the children in the studies, 44 percent were younger than 2. Of these children, 51.8 percent had recurrent ear infections. It was in this group of children that the risk of fluid buildup was the greatest.

Rovers' group found that the children taking antibiotics were 90 percent as likely to develop fluid buildup as children who weren't taking the medications. However, this difference was not statistically significant. "No difference in the development of effusion could be detected between the placebo and the antibiotics group," Rovers said.

"More research is, however, needed to identify relevant subgroups of children that have middle ear effusion that might benefit from other treatments," Rovers added.

One expert noted that doctors do not routinely prescribe antibiotics to prevent fluid buildup in ear infections.

"To the best of my knowledge, physicians generally don't prescribe antibiotics for acute otitis media in order to prevent middle-ear effusion; they prescribe them to bring about more prompt resolution of the infection and of its symptoms, especially pain," said Dr. Jack Paradise, a professor of pediatrics and otolaryngology at the University of Pittsburgh School of Medicine and a pediatrician at Children's Hospital of Pittsburgh.

The question of prescribing to prevent middle-ear effusion has become a non-issue over the past decade, Paradise said. "Asymptomatic middle-ear effusion is extraordinarily common and has been shown to be essentially harmless under ordinary circumstances," he said.

More information

For more about otitis media, visit the U.S. National Library of Medicine.