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Nicotine Exposure During Pregnancy May Lead to ADHD in Future Generations

If GCigarette Endsrandma smoked during pregnancy, her nicotine habit could cause ADHD in her future grandchildren. A new study from researchers at the Florida State University College of Medicine as published in The Journal of Neuroscience suggests that nicotine exposure during pregnancy could manifest as attention deficit hyperactivity disorder (ADHD) in children born a generation later.

If a grandmother smoked during pregnancy, that a mother never smoked may be irrelevant for the development of ADHD in her children.

Explains Professor Pradeep G. Bhide, chair of developmental neuroscience and director of the Center for Brain Repair at the College of Medicine, “What our research and other people’s research is showing is that some of the changes in your genome – whether induced by drugs or by experience – may be permanent and you will transmit that to your offspring.”

Using a rodent model, Prof. Bhide and Professor Jinmin Zhu, assistant professor of biomedical sciences, tested the hypothesis that hyperactivity as a result of nicotine exposure during pregnancy is transmitted from one generation to the next.

The results of the study demonstrate a transgenerational transmission via the maternal, but not the paternal, line of descent. In other words, use of nicotine by female members of a family can cause behavioral problems in subsequent generations.

States Prof. Bhide, “Genes are constantly changing. Some are silenced and others are expressed, and that happens not only by hereditary mechanisms, but because of something in the environment or because of what we eat or what we see or what we hear. So the genetic information that is transmitted to your offspring is qualitatively different than the information you got from your parents. This is how things change over time in the population.”

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ADHD is a neurobehavioral disorder that affects approximately 10 percent of children and five percent of adults in the United States alone. Researchers have long been perplexed by the recent increase in ADHD diagnoses.

Comments Prof. Bhide, “Some reports show up to a 40 percent increase in cases of ADHD – in one generation, basically. It cannot be because a mutation occurred; it takes several generations for that to happen.”

One hypothesis for the increase relates to a greater number of women smoking during pregnancy as cigarettes became fashionable in the United States around the time of World War II. Previous research suggests a link between heavy smoking during pregnancy and an increased risk of ADHD.

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Adds Prof. Bhide, “What’s important about our study is that we are seeing that changes occurring in my grandparents’ genome because of smoking during pregnancy are being passed to my child. So if my child had ADHD it might not matter that I did not have a disposition or that I never smoked.”

The researchers do caution that the results of the study are not conclusive for humans. Additionally, not all children born to mothers who smoke will develop ADHD and not all individuals will transmit the genetic material responsible for ADHD.

Conclude the researchers, “But our work has opened up new possibilities. The next question is how does transmission to future generations happen? What is the mechanism? And the second question is, if the individual is treated successfully would that stop the transmission to future generations?”

Two other recent studies found that nicotine replacement during pregnancy increases the risk of obesity in offspring and smoking during pregnancy increases the risk for nicotine dependence later in life in daughters.

References

FSU researchers link prenatal nicotine exposure to future ADHD: http://www.news-medical.net/news/20140228/FSU-researchers-link-prenatal-nicotine-exposure-to-future-ADHD.aspx
Prenatal nicotine exposure may lead to ADHD in future generations: http://www.medicalnewstoday.com/releases/273621.php

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Cigarette Ends: http://www.freeimages.com/photo/937787