Methamphetamine tied to abnormal brain development

NEW YORK (Reuters Health) - In children who were exposed to methamphetamine during pregnancy, MRI findings suggest that alterations in the maturation of white matter occur, according to a report in an online issue of Neurology.

"Methamphetamine use is an increasing problem among women of childbearing age, leading to an increasing number of children with prenatal meth exposure," senior author Dr. Linda Chang, from the University of Hawaii, Honolulu, said in a statement. "But until now, the effects of prenatal meth exposure on the developing brain of a child were little known."

Chang and colleagues performed an MRI test that allows assessment of the brain's microstructure, in 66 children between 3 and 4 years old; 29 were exposed to methamphetamine prenatally and 37 were not.

The methamphetamine-exposed children showed 2 percent to 4 percent less diffusion of molecules in the frontal and parietal white matter compared with the unexposed controls. There was also evidence of more extensive variation in the left frontal white matter among exposed children.

According to Chang, exactly how prenatal methamphetamine exposure causes lower brain diffusion is unclear, but lower diffusion in white matter usually means that nerve fibers are compacted.

Longitudinal studies are now underway, the authors note, to see if these changes in white matter in the methamphetamine-exposed children are permanent.

SOURCE: Neurology, April 15, 2009.