Health Highlights: Feb. 20, 2008

They made the conclusion after analyzing a database of 335 emerging infectious disease events that occurred between 1940 and 2004,CBC Newsreported. The study appears in the Feb. 21 issue of the journalNature.

The researchers wrote that "that human population density was a common significant independent predictor of emerging infectious disease events," and noted that this finding "supports previous hypotheses that disease emergence is largely a product of anthropogenic and demographic changes and is a hidden cost of human economic development."

They recommended that richer developed countries provide resources to ensure proper infectious disease monitoring in poorer, less-developed nations,CBC Newsreported.

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One Cigarette Can Cause Tobacco Addiction

In some people, smoking a single cigarette can trigger tobacco addiction, says a New Zealand study that included 96,000 youngsters, ages 14-15. The participants provided information about whether they smoked and whether they felt the need to continue smoking.

As expected, regular smokers said they felt the urge to continue smoking. But the researchers were surprised to find that 46 percent of those who smoked less than one cigarette a month said they had the urge to continue smoking,Agence France-Pressereported.

And among those who said they had trouble suppressing the urge to smoke, 10 percent had the urge within two days of smoking their first cigarette and 25 percent within one month of their first cigarette.

The study authors concluded that "these data suggest that smoking one cigarette in total can prompt a loss of autonomy,"AFPreported.

The findings were published Wednesday in the journalAddictive Behaviors.

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Anger Slows Injury Recovery

People who can't control their anger take longer to recovery from injury, says a University of Ohio study in the journalBrain, Behavior, Immunity.

Researchers inflicted minor burns on the arms of 98 volunteers and then monitored the healing process for eight days,Agence France-Pressereported. Before the burns were inflicted, the participants underwent psychological tests to determine where they ranked on an anger scale.

The study found that people who had trouble controlling expressions of anger were four times more likely to need more than four days for their burn wounds to heal than those who were able to control their anger.

Participants unable to control their anger also had higher secretions of the stress hormone cortisol, which may partly explain their longer healing time, the researchers said.

They suggested that anger control therapy could help certain patients heal more quickly after injury or surgery,AFPreported.

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Feeding May Affect Preterm Infants' Brain Development

The type of nutrition preterm infants receive during the first few weeks of life may have a major impact on brain development, says a U.K. study in the journalPediatric Research.

Preterm infants who were fed enriched formula milk in the first few weeks after birth consistently did better on childhood IQ tests than other preterm babies, and the difference continued into the teenage years,BBC Newsreported.

The research team from Great Ormond Street Hospital for Children and the UCL Institute of Child Health in London also found that the infants who were fed the enriched formula had better development of a part of the brain called the caudate nucleus, which is associated with memory and learning.

Previous studies have noted an association between nutrition and behavior, but this is one of the first studies to suggest that feeding early in life may affect brain structure, the researchers said according toBBC.