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MEREDITH DESMOND

Are some people genetically predisposed to anorexia nervosa? New research published in the Archives of General Psychiatry suggests that 56 percent of the risk for developing the disease is genetic. Researchers reviewed data on more than 31,000 Swedish twins born between 1935 and 1958 and examined seven potential predictors for the development of anorexia in women. The tendency to exhibit neurotic symptoms early in life, usually a genetic condition, was the only predictor identified as a risk factor for anorexia. Researchers say those with inherited neurotic disorders are more sensitive to environmental factors that trigger anorexia. The authors hope to one day identify a gene to help predict and treat anorexia more effectively. (Arch Gen Psychiatry, March 2006)

There is new treatment for patients with stroke who have impaired arm function. Results of a study published in Stroke claim that rehabilitation programs in which a patient's good arm is constrained after a stroke can cause significant improvement in the damaged arm. Researchers recruited 41 patients with chronic motor deficit and assigned 21 to a rehabilitation group that required the better arm to be constrained for 90 percent of waking hours. The other patients were enrolled in a general fitness program. After two weeks, the rehabilitation group showed a 1.8-point mean increase in motor activity log score, whereas the control group had no change. Researchers suggest that the therapy reorganizes the brain and causes it to recruit new brain areas to influence movement in the affected arm. (Stroke, April 2006)

Women who take birth control pills may have a higher risk of migraines. According to a study published in Neurology, women taking oral contraceptives (OCs) are 40 percent more likely to have migraine headaches and 20 percent more likely to have nonmigraine headaches than women who do not take OCs. Researchers point out that many women have migraine headaches during menstruation, when estrogen levels in the body drop. The risk of headache is particularly increased for women taking OCs because the pills boost estrogen levels up to four times their normal range before the drop. (Neurology, February 2006)

Does body weight affect a person's chances of dying in a motor vehicle crash? According to a study published in the American Journal of Public Health, men with a body mass index (BMI) of less than 22 [kg per m2] or more than 35 have a significantly higher chance of dying in a motor vehicle crash. Investigators analyzed data from more than 22,000 drivers involved in crashes between 1997 and 2001 and found that being underweight or obese contributed to the likelihood of fatality. Men with a BMI of around 28, which is considered overweight but not obese, were the least likely to die because of what researchers called a "cushioning effect." BMI did not affect the risk of death among women in the study. (Am J Public Health, April 2006)

Teenagers who cut back on soda could lose one pound every three to four weeks, according to a study published in Pediatrics. The study included 103 teenagers between 13 and 18 years of age who reported drinking at least one serving of sugar-sweetened beverages every day. (Sugar-sweetened beverages included soft drinks, juice drinks, punches, lemonade, iced tea, and sports drinks.) One half of participants were asked to replace their sweetened drinks with any noncaloric drink (including water, no-calorie juice drinks, or diet sodas) for six months, whereas the rest continued their normal drinking habits. At the end of the study, the noncaloric beverage group saw a modest decrease in BMI, and the most overweight teens saw a decrease of about one pound per month. (Pediatrics, March 2006)

Being inside a taxi cab can increase your exposure to pollution, according to a study published in Atmospheric Environment. Investigators used video cameras and a special counter that measures pollutant particles to study five kinds of transportation: bicycles, cars, taxis, buses, and walking. In taxis, riders were exposed to more than 100,000 ultrafine pollution particle counts per cm3, the worst of all five categories. Walking had the lowest particle count, resulting in the least exposure to pollution. Investigators attributed the amount of ultrafine particles in taxis to the fact that they are on the road for much longer each day than noncommercial cars. (Atmos Environ, January 2006)