NEW YORK (Reuters Health) – In children exposed in utero to methamphetamine, MRI findings suggest alterations in white matter maturation, according to a report in the April 15th 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.”

Dr. Chang and colleagues performed diffusion tensor MRI, which allows assessment of brain microstructure, in 66 children at 3-4 years of age; 29 had been exposed prenatally to methamphetamine, 37 had not.

The methamphetamine-exposed children showed 2% to 4% less diffusion of molecules in the frontal and parietal white matter compared to the unexposed controls. There was also evidence of higher fractional anisotropy in the left frontal white matter of exposed children.

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

Longitudinal studies are now underway, the authors note, that will determine if the white matter changes seen in the methamphetamine-exposed children are permanent.

Reference:
Neurology 2009.