A new study by the University of Leicester has examined the relationship between maternal smoke during Pregnancy and offspring conduct problems among children. Smoking during pregnancy appears to be a prenatal risk factor for conduct disorder such as attention deficit disorder which represents an issue of significant social, clinical, and practice concern, with evidence highlighting increasing rates of child conduct problems internationally.
Professor Gordon Harold and Dr. Darya Gaysina, of the University of Leicester, with colleagues in the United States and New Zealand, examined the relationship between maternal smoking during pregnancy and offspring conduct problems among children raised by genetically related mothers and genetically unrelated mothers.
In this study maternal smoking during pregnancy was measured with the average number of cigarettes per day smoked during pregnancy and it was determined that there was a significant association between maternal smoking during pregnancy and offspring conduct problems among children raised by genetically related mothers and genetically unrelated mothers. Results from a meta-analysis affirmed this pattern of findings across pooled study samples.
“Our findings suggest an association between pregnancy smoking and child conduct problems that is unlikely to be fully explained by postnatal environmental factors (i.e., parenting practices) even when the postnatal passive genotype-environment correlation has been removed.” The authors conclude, “The causal explanation for the association between smoking in pregnancy and offspring conduct problems is not known but may include genetic factors and other prenatal environmental hazards, including smoking itself”.
An earlier study had linked maternal smoking with myelin deficits observed in adults with various psychiatric disorders,” said Ming Li, PhD, of the University of Virginia, who directed the study. “Our findings suggest that abnormal myelination may also contribute to the psychiatric disorders associated with maternal smoking,” Li said.
Myelin is a fatty brain substance that insulates brain cell connections. The study found that when rats were given nicotine during pregnancy, their offspring showed changes in myelin genes in specific regions of their brain’s limbic system — structures involved with emotion. The effect was strongest in the prefrontal cortex, a brain region important for decision-making.
The researchers also identified sex differences in nicotine’s effects. Myelin-related genes increased in the prefrontal cortex of the male offspring, but decreased in the females. The opposite was observed in the hypothalamic paraventricular nucleus, a brain region involved in the regulation of stress and appetite, among other functions.
“These findings suggest that maternal smoking may affect daughters and sons differently,” Li said. Research was supported by the National Institute on Drug Abuse.
Gaysina D, Fergusson DM, Leve LD, et al. Maternal Smoking During Pregnancy and Offspring Conduct Problems: Evidence From 3 Independent Genetically Sensitive Research Designs. JAMA Psychiatry, 2013; DOI: 10.1001/jamapsychiatry.2013.127