In Brief

In Brief

April 14, 2006


Men more affected by amphetamines

Amphetamines appear to have a greater effect on men's brains than women's, a finding that could help doctors develop better treatments for addiction and neurological diseases, according to a study by the Johns Hopkins School of Medicine.

The research found that men's brains showed up to three times the amount of the chemical dopamine as women's when exposed to amphetamines. Hopkins scientists will publish the results July 1 in The Journal of Biological Psychiatry.

Dopamine is a neurotransmitter that can increase heart rate and blood pressure and makes it possible for the brain to control movement. Linked to the brain's so-called pleasure system, dopamine is released in the presence of such high-producing drugs as amphetamines and cocaine.

"These appear to be the first clinical studies whose results may help explain why we see a greater number of men abusing amphetamines than women," said Dr. Gary S. Wand, a professor of endocrinology and lead author of the study.



Pregnancy length down to 39 weeks

Children grow up so fast -- and now they are getting an earlier start on the process. The most common length of pregnancy in the United States is now 39 weeks, down from 40, March of Dimes researchers have found. Forty weeks has traditionally been considered the benchmark for a full-term birth.

Analyzing data from the National Center for Health Statistics on all live U.S. births in 1992, 1997 and 2002, researchers identified a notable overall shift toward shorter gestational periods, with more births at 34 to 39 weeks and fewer at 40 and longer.

The shift can be attributed in part to increasing rates of Caesarean sections and induced births, and an increasing reluctance among physicians to let pregnancies go past term. "I would say it's probably more of an evolution of practice than an evolution of the species," says Dr. Diane Ashton, associate medical director of the March of Dimes.

Consistent with this, the study found a 21 percent decrease in births at week 40 or longer. Medically, the ideal gestational period, assuming there's no extenuating medical condition, is 39 to 40 weeks, Ashton says, although 37 weeks and beyond is considered full-term.

The study was published in March as a supplemental edition of the journal Seminars in Perinatology.



Snoring linked to family, allergies

Snoring appears to run in families and disproportionately affects babies with allergies, researchers at Cincinnati Children's Hospital Medical Center reported this week. Children are about three times more likely to snore if their parents snore, according to a study of 681 toddlers averaging 1 year old.

The babies seemed particularly susceptible to snoring if they were sensitive to allergens, according to research published in the journal CHEST. "We found that snoring was associated with the presence of allergic sensitization, a condition called atopy," said Dr. Maninder Kaira, a pulmonologist at the hospital.

Children with atopy were more than twice as likely to snore at least three times a week as were children without allergies.

Snoring is one symptom of obstructive sleep-disordered breathing. In older children, the condition has been linked to behavioral problems and cognitive deficits, so parents should have doctors evaluate young snorers, the researchers said.



Kidney shock waves may increase risks

The common practice of using shock waves to break up kidney stones may increase risks of diabetes and high blood pressure later in life, researchers said.

Researchers combed through medical charts of 630 patients treated with the procedure known as lithotripsy in 1985. Nearly two decades later, those given shock wave treatment were almost four times more likely to have diabetes and 50 percent more likely to have high blood pressure than a comparison group treated with drugs, said the study in the Journal of Urology.

The stones, comprised of tiny crystals formed from various minerals, can cause pain, fever, burning and nausea.

"This is a completely new finding," said lead researcher Dr. Amy Krambeck, a urology resident at the Mayo Clinic in Rochester, Minn. "We can't say with 100 percent certainty that the shock wave treatment for the kidney stones caused diabetes and hypertension, but the association was very strong."

About 10 percent of men and 5 percent of women develop kidney stones before the age of 70, according to the National Institute of Diabetes and Digestive and Kidney Diseases.



Smell of fear aids women's accuracy

Women can unconsciously detect the smell of fear, new research suggests, and the smell improves their performance on mental tasks. Scientists collected sweat from seven volunteers -- four men and three women -- who watched horror movies while holding gauze pads in their armpits. Then, their sweat was collected while they watched videos with neutral emotional content.

Sixty-eight women next performed a word-association task while smelling the pads. The task involved watching two words flash on a screen one after the other, and then stating whether the two words were related. ("Arms" and "legs" are related; "arms" and "wind" are not.)

Without sacrificing speed, the women smelling the fear pads were more accurate than those in the other two groups when processing meaningful related words. There was no difference in speed or accuracy between the three groups when the words were not related.


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