Knowing the pattern of damage could help with diagnosis of affected children
It has long been known that alcohol exposure is toxic to the developing fetus and can result in lifelong brain, cognitive and behavioral problems. Now, a new report out of UCLA shows that the effects of prenatal methamphetamine exposure - or worse, a combination of methamphetamine and alcohol - may be even more damaging.
Reporting in the March 17 issue of the Journal of Neuroscience, UCLA professor of neurology Elizabeth Sowell and her colleagues used structural magnetic resonance imaging (sMRI) to show for the first time that individuals whose mothers abused methamphetamine during pregnancy, with or without alcohol abuse, had structural abnormalities in the brain that were more severe than those seen in children whose mothers abused alcohol alone.
The researchers identified the brain structures that are vulnerable in such exposure, which may help predict particular learning and behavioral problems in methamphetamine-exposed children.
"We know that alcohol exposure is toxic to the developing fetus and can result in lifelong problems," said Sowell, the study's senior author. "In this study, we show that the effects of prenatal meth exposure, or the combination of meth and alcohol exposure, may actually be worse, and our findings stress the importance of seeking drug-abuse treatment for pregnant women."
In particular, said Sowell, a structure in the brain called the caudate nucleus, which is important for learning and memory, motor control, and punishment and reward, was one of the regions that was more reduced by methamphetamine than alcohol exposure.
Of the more than 16 million Americans over the age of 12 who have used methamphetamine, about 19,000 have been pregnant women, according to 2002 data from the National Survey on Drug Use and Health.
"About half of women who say they used meth during pregnancy also used alcohol," Sowell said, "so isolating the effects of meth on the developing brain was difficult."
The researchers overcame this challenge, she said, by recruiting women who abused alcohol but not methamphetamine during pregnancy and compared them to the children with exposure to both drugs, and to a group that was not exposed.
The neuroscientists evaluated the specific effects of prenatal methamphetamine exposure by comparing brain scans of 61 children, whose average age was 11. Of these, 21 had prenatal methamphetamine and alcohol exposure, 13 had heavy alcohol exposure only and 27 were unexposed. Structural magnetic resonance imaging showed that the sizes and shapes of certain brain structures varied depending on prenatal drug exposure.
Previous studies have shown that certain brain structures are smaller in alcohol-exposed children. In this study, the authors found that these brain regions in methamphetamine-exposed children were similar to those in alcohol-exposed children and that in some areas they were even smaller. Some brain regions were larger than normal. For example, an abnormal volume increase was noted in methamphetamine-exposed children in a region called the cingulate cortex, which is associated with control and conflict resolution.
"Either scenario - smaller or larger growth - could be a bad thing in kids with prenatal drug exposure," Sowell noted. "There are enormous developmental changes that take place during adolescence. These drugs are likely altering the trajectory of development, and clearly not in a good way."
This brain imaging may also aid in treatment. Because the researchers were also able to predict a child's past exposure to drugs based on imaging and IQ information, detailed data about vulnerable brain structures may eventually be used to diagnose children with cognitive or behavioral problems, even when well-documented histories of drug exposure are not available.
"The tragedy here is that all these developmental problems are 100 percent avoidable," Sowell said. "The important message is to urge drug abusing women to seek treatment during pregnancy."
Source: University of California - Los Angeles