SEP 12, 2016 6:29 AM PDT

Maternal Smoking Increases Risks of Tourette's in Baby

There are undeniable evidence that smoking is harmful to your health. And as a corollary to that, smoking during pregnancy is arguably as equally damaging for the fetus. But it’s been surprisingly hard for scientists to pinpoint this association because of many confounding variables.
Now, using a huge epidemiological data set of over 73,000 women, scientists have teased apart many factors that link the health of the mother and that of the baby. And they’ve found that smoking during pregnancy is, indeed, highly associated with chronic psychiatric disorders like Tourette syndrome and tic disorders.
As part of a spectrum of tic disorders, Tourette syndrome is characterized by multiple motor tics and vocal tics. The onset is usually in childhood and carried to adulthood, wherein the affected person has rapid, non-rhythmic, and repetitive movements or oral exclamations that may be inappropriate or obscene. This disorder often accompanies other nervous system disorders, such as attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), and anxiety and depression.
Doctors have long noted that moms-to-be who smoke are at higher risks of having babies with behavioral and neuropsychiatric problems. However, many factors make it difficult to say that smoking was the culprit. For example, mothers who smoke have a higher chance of also being diagnosed with a neuropsychiatric disorder, which they could then pass on to their baby. And because babies exposed to nicotine in the womb are more likely to be born preterm, it is unclear if the smoking or the birth complications contribute to the tic disorders.

To pinpoint smoking, researchers would have to tease apart these confounding factors. And that’s exactly what the team at the Icahn School of Medicine at Mount Sinai in New York, and Aarhus University in Denmark did. Their dataset was from the Danish National Birth Cohort, which included over 73,000 registered pregnancies.
With this, they were able to control for factors like maternal age, psychiatric disorder, exposure to alcohol, as well as other gestational effects. They found that smoking can increase the risk for tic disorders by as much as 66 percent. In other words, mothers who were heavy smokers were 2- to 3 times more likely to have a child who will develop tic disorders, ADHD, or pediatric OCD.
"Identifying environmental causes for chronic tic disorders and related psychiatric conditions is important because if we know specific risk factors, we can develop more effective strategies for prevention," said Dorothy Grice, professor at the Icahn School of Medicine and senior author on the study.

Additional source: Elsevier via EurekAlert!
About the Author
Doctorate (PhD)
I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at
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