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Prenatal meth exposure may harm baby's brain

By REUTERS

* Prenatal methamphetamine exposure tied to abnormalities

* Researchers say changes may explain developmental delays

By Julie Steenhuysen

CHICAGO (Reuters) - Children whose mothers took methamphetamine during pregnancy have brain abnormalities that may explain the developmental problems they often experience, U.S. researchers said Wednesday.

Brain scans on a group of 3- and 4-year-old children showed abnormal development in the white matter, which carries messages across the brain, compared with children who did not have prenatal exposure to the drug, often called "meth."

The study provides some of the first physical evidence to show brain changes that can occur during fetal development when the mother used the drug during pregnancy.

"Methamphetamine use is an increasing problem among women of childbearing age, leading to an increasing number of children with prenatal meth exposure," Dr. Linda Chang of the University of Hawaii, whose study appears in the journal Neurology, said in a statement.

Methamphetamine is a highly addictive stimulant that users inject, snort, smoke or swallow.

A U.S. government survey showed that in 2007, about 13 million Americans ages 12 and up reported using methamphetamine at least once in their lifetimes, or 5 percent of them.

Chang and colleagues used a new magnetic resonance imaging, or MRI, technique known as diffusion tensor imaging to look for abnormalities in tiny brain structures.

"It's actually measuring how quickly water molecules are bouncing around in the brain," Chang said in a telephone interview.

Her team studied 29 3- and 4-year-olds whose mothers used methamphetamine during pregnancy, comparing them to 37 children of the same ages whose mothers did not use the drug.

The scans showed that children with prenatal meth exposure had differences in the white matter structure and maturation of their brains compared to unexposed children.

"The movement of the water was lower than it should be compared to children who were not exposed to meth," suggesting that the brain tissue was more densely packed that normal, Chang said.

"We think that's due to the meth," Chang added.

"Animal studies have shown if you give meth to an animal, their brain tissue becomes more densely packed," Chang said.

She said her team now plans to follow the children as they grow to see if these differences persist.

"Such abnormal brain development may explain why some children with prenatal meth exposure reach developmental milestones later than others," she said.

Chang said other studies have suggested that children exposed to meth prenatally have trouble with attention and memory. But because many of these children also are exposed to second-hand cigarette smoke and other environmental problems in the home, it has been hard to sort out which changes are specifically caused by meth exposure, Chang added.

(Editing by Maggie Fox and Will Dunham)

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