A top Las Vegas casino resort has issued a health warning to past guests after six people came down with Legionnaire's disease, health authorities said Monday.

Citing "an abundance of caution," the Aria Resort & Casino has written to people who stayed there between June 21 and July 4 when tests showed elevated levels of Legionella bacteria in some of its guest rooms.

Binge-drinking can have a long-lasting negative effect on the brains of teenaged girls, hitting them harder than it does young boys, a study released Friday shows.

Researchers from the University of California, San Diego (UCSD) and Stanford University found that girls who binge-drink -- defined as having four or more drinks for women and five or more for men -- showed less activity in several brain regions than teetotal teenagers, both girl and boy, the study said.

Kids may be safest in cars when grandma or grandpa are driving instead of mom or dad, according to study results that even made the researchers do a double-take.

"We were surprised to discover that the injury rate was considerably lower in crashes where grandparents were the drivers," said Dr. Fred Henretig, an emergency medicine specialist at Children's Hospital of Philadelphia and the study's lead author.

A large study in older veterans raises fresh concern about mild brain injuries that hundreds of thousands of troops have suffered from explosions in recent wars. Even concussions seem to raise the risk of developing Alzheimer's disease or other dementia later in life, researchers found.

Closed-head, traumatic brain injuries are a legacy of the Afghanistan and Iraq wars. Body armor is helping troops survive bomb blasts, but the long-term effects of their head injuries are unknown.

Researchers have found a new way to control the amount we eat: use a bigger fork.

While numerous studies have focused on portion sizes and their influence on how much we eat, researchers Arul and Himanshu Mishra and Tamara Masters looked at how bite sizes affect quantities ingested.

The number of U.S. movies in which an actor lights up fell sharply between 2005 and 2010, and this could have contributed to the decline in smoking among U.S. teens, a study released Thursday says.

A majority of movies -- 55 percent -- that scored huge box office success in the United States in 2010 had no scenes that included tobacco use, compared with a third of top-grossing films in 2005, the study released by the Centers for Disease Control and Prevention (CDC) says.

Siestas, a health diet -- and genetics -- could explain why people on the tiny Aegean island of Ikaria live so long, said a study by Greek cardiologists released Wednesday.

"While in the rest of Europe only 0.1 percent of the population is over 90 years old, in Ikaria the figure is tenfold, 1.1 percent," Christina Chrysohoou, a cardiologist at the Athens university school of medicine, told Agence France Presse.

The odor of dirty socks can be used to lure mosquitoes into a deadly trap before they can spread malaria, a U.S. and Canadian-funded researcher based in Africa said Wednesday.

Dr. Fredros Okumu, of the Ifakara Health Institute in Tanzania, discovered through an experiment that mosquitoes were more attracted to the odor of filthy feet than to live humans sleeping in the same area.

A former police officer who weighs 140 Kg was denied the right to obesity surgery will take his case to the Court of Appeals on Monday.

Tom Condliff, 62, says he needs the stomach operation to save his life but the North Staffordshire Primary Care Trust has ruled that his body mass index is not high enough to entitle him to funding for a gastric bypass operation.

Spanish surgeons on Monday carried out the world's first-ever double leg transplant, authorities in the eastern city of Valencia said.

The operation lasted all night and was completed on Monday morning in the city's La Fe hospital, the regional health authority said in a statement.