Tuesday, March 23, 2010
Meth Babies—Fact or Fiction?
Research team finds brain abnormalities.
When it came to babies born to crack-addicted mothers, the media went overboard, creating a crisis in the form of an epidemic that never quite was. By contrast, when it came to babies born to alcoholic mothers, Fetal Alcohol Syndrome went unrecognized in the science and medical community until 1968.
Now comes a study on prenatal methamphetamine exposure in The Journal of Neuroscience, headed up by Elizabeth Sowell of the University of California, Los Angeles, with support from both the National Institute on Drug Abuse (NIDA) and the National Institute of Alcoholism and Alcohol Abuse (NIAAA.) The report garnered considerable media attention. “We know that alcohol exposure is toxic to the developing fetus and can result in lifelong brain, cognitive and behavioral problems,” Sowell said in a press release. “In this study, we show that the effects of prenatal meth exposure, or the combination of meth and alcohol exposure, may actually be worse.”
It makes sense that meth might effect the health of unborn children. There is a modest body of research to support the notion. The Sowell study points a finger at the caudate nucleus, a brain region involved with learning and memory. The study showed that the caudate nucleus of the meth-using group was reduced in size. “Identifying vulnerable brain structures may help predict particular learning and behavioral problems in meth-exposed children,” the press release optimistically states. And the potential problem is real enough: More than 16 million Americans have used meth, according to government numbers. An estimated 19,000 of these users are pregnant women.
But is this particular study a definitive one? The icing on the cake? To begin with, the press release from The Journal of Neuroscience admits to a major problem right up front: “About half of women who say they used meth during pregnancy also used alcohol, so isolating the effects of meth on the developing brain is difficult.” Even in cases of meth exposure only, there are a host of negative behavioral factors that often accompany meth addiction (bad nutrition, minimal health care, poor health) that can significantly effect fetal development.
The study team compared the MRI brain scans of 61 children: “21 with prenatal MA (methamphetamine) exposure, 18 with concomitant prenatal alcohol exposure (the MAA group), 13 with heavy prenatal alcohol but not MA exposure (ALC group), and 27 unexposed controls. While finding “striatal volume reductions,” as well as increases in the size of certain limbic structures in both groups with meth and/or alcohol exposure, the researchers conclude that striatal and limbic structures “may be more vulnerable to prenatal MA exposure than alcohol exposure.” However, that conclusion was apparently reached despite the fact that only 3 of the 61 children under study were born to mothers who did meth, and meth only, during pregnancy.
Furthermore, there is significant controversy over brain scan studies that measure gross anatomical changes in the size of specific brain regions, rather than brain region activity based on blood flow.
Is there other evidence for the danger of meth use during pregnancy? There is, but as is frequently the case, some of the best evidence comes from animal studies. A 2008 guinea pig study by Sanika Chirwa showed neural damage to the hippocampus, another region involved in memory, in newborn animals with prenatal meth exposure. Furthermore, the newborn animals showed an impaired ability to distinguish novel objects from familiar ones.
In 2006, a study at Brown Medical School, published in Pediatrics , found that newborns exposed to meth during pregnancy were born “small for gestational age,” meaning they were born full-term, but smaller than babies not exposed to meth in utero. According to study author Barry Lester, “Children who are born underweight tend to have behavior problems, such as hyperactivity or short attention span, as well as learning difficulties.”
However, Lester added an important caveat in a Brown University press release : “I hope that the ‘crack baby’ hysteria does not get repeated. While these children may have some serious health and developmental challenges, there is no automatic need to label them as damaged and remove them from their biological mothers.”
Similar caution was urged by the authors of a 2009 report in the Journal of Developmental and Behavioral Pediatrics: “Efforts to understand specific effects of prenatal methamphetamine exposure on cognitive processing are hampered by high rates of concomitant alcohol use during pregnancy.”
In 2005, an open letter from the Center for Substance Abuse Research at the University of Maryland warned about the dangers of hyperbole, calling upon the media and public officials to “stop perpetuating ‘meth baby’ myths.” The Center argued that “The terms ‘ice babies’ and ‘meth babies’ lack medical and scientific validity and should not be used,” and requested that “policies addressing prenatal exposure to methamphetamines and media coverage of this issue be based on science, not presumption or prejudice.”
Sowell, E., Leow, A., Bookheimer, S., Smith, L., O'Connor, M., Kan, E., Rosso, C., Houston, S., Dinov, I., & Thompson, P. (2010). Differentiating Prenatal Exposure to Methamphetamine and Alcohol versus Alcohol and Not Methamphetamine using Tensor-Based Brain Morphometry and Discriminant Analysis Journal of Neuroscience, 30 (11), 3876-3885 DOI: 10.1523/JNEUROSCI.4967-09.2010
Smith, L., LaGasse, L., Derauf, C., Grant, P., Shah, R., Arria, A., Huestis, M., Haning, W., Strauss, A., Grotta, S., Liu, J., & Lester, B. (2006). The Infant Development, Environment, and Lifestyle Study: Effects of Prenatal Methamphetamine Exposure, Polydrug Exposure, and Poverty on Intrauterine Growth PEDIATRICS, 118 (3), 1149-1156 DOI: 10.1542/peds.2005-2564
Photo credit: http://www.psychiatry.emory.edu