Prenatal Exposure To Drugs, Alcohol And Tobacco Affect The Brain Into Early Adolescence

Note this study does not mean that these drugs don't have an effect after adolescence. It's unlikely that they effects will suddenly stop at this point in time.

http://www.sciencedaily.com/releases/2008/04/080407153034.htm

ScienceDaily (Apr. 8, 2008) — Although behavioral studies clearly indicate that exposure to drugs, alcohol and tobacco in utero is bad for a baby's developing brain, specific anatomic brain effects have been hard to tease out in humans. Often users don't limit themselves to one substance, and demographic factors like poverty can also influence brain development.

Now, a new study using magnetic resonance imaging (MRI) brain scans, led by Children's Hospital Boston neurologist Michael Rivkin, MD, suggests that prenatal exposure to cocaine, alcohol, marijuana or tobacco (alone or in combination) may have effects on brain structure that persist into early adolescence. The findings, published in Pediatrics, are of public health significance, the researchers say, since it's estimated that more than 1 million babies born annually in the United States have been exposed to at least one of these agents in utero.

Researchers at Children's and Boston Medical Center employed volumetric MRI imaging to study the brain structure of 35 young adolescents prenatally exposed to cocaine, marijuana, alcohol or tobacco. The children, who averaged 12 years old at the time of imaging, were part of part of an historic cohort of children assembled by Deborah Frank, MD at Boston Medical Center and followed there since birth. Prenatal exposures were confirmed by a combination of maternal history, urine testing of the mother or urine or meconium (stool) testing of the infants at birth.

"We found that reductions in cortical gray matter and total brain volumes were associated with prenatal exposure to cocaine, alcohol or cigarettes," says Rivkin, who is first author on the study. "Importantly, although volume reductions were associated with each of these three prenatal exposures, they were not associated with any one of these substances alone after controlling for other exposures."

Notably, the effects were found to be additive--the more substances a child was exposed to in utero, the greater the reduction in brain volume.