Prenatal Smoking May Lead to Learning Disabilities in Children
It is well known that prenatal exposure to nicotine is harmful to the fetus, and new research shows that exposure to nicotine may lead to learning disabilities in offspring. Researchers from the University of Alabama at Birmingham found that prenatal exposure to nicotine leads to a decrease in adult stem cells and a change in the offspring’s synaptic plasticity in the hippocampus. This could be a cause for behavioral disorders such as attention-deficit hyperactivity disorder (ADHD) in children whose mothers smoked during pregnancy.
The hippocampus is the area of the brain that is associated with learning and memory, and adult stem cells in this region divide and produce new cells over a person’s lifetime. The researchers found that exposing rats to nicotine during pregnancy led to a decreased number of new cells in the hippocampus.
Robin Lester, Ph.D., primary investigator for the study and associate professor in the Department of Neurobiology at the University of Alabama at Birmingham, said that the decreased number of new cells in the hippocampus leads to disruption of the learning process, which could explain some behavioral problems in children whose mothers smoked during pregnancy, including cognitive defects, learning disabilities, attention-deficit hyperactivity disorder, and increased susceptibility to substance abuse and addiction.
About 20 percent of pregnant women still smoke, according to the World Health Organization. Shay Hyman, a doctoral student, says nicotine and other addictive drugs have been shown to similarly affect newborn cells when given to older animals, but the new study shows that the effects are more dramatic with newborns and may contribute to the mechanism underlying behavioral problems. Hyman added that this study adds to the growing body of evidence showing that pregnant women should seek treatment for nicotine addiction.
Lester said that the next step will be to replicate these findings under conditions that more closely resemble human smoking, which could involve allowing rats to press a lever to decide whether to receive nicotine or not.
Source: Science Daily, Nicotine Exposure in Pregnant Rats Puts Offspring at Risk for Learning Disabilities, December 6, 2010
