Prenatal Exposure to Nicotine
Spells Trouble Later
Study suggests lasting brain damage and susceptibility
By Kathleen Doheny
Women who smoke
during pregnancy expose their unborn babies to nicotine that may inflict
lasting brain damage, new research claims.
These children may also be more prone to pick up the smoking habit
as teens, said Theodore Slotkin, a professor of pharmacology, psychiatry,
and neurobiology at Duke University Medical Center. Philip Morris
USA supported the research, although the scientists have no financial
ties to the tobacco company.
The studies involved animals, but Slotkin said the findings apply
to humans. His team focused on animals to try to prove a biological
link between smoking during pregnancy and later cognitive problems
and addiction, he added.
"We already know that the offspring of women who smoke during
pregnancy are more likely to become smokers in adolescence themselves,"
he said. "Those relationships are statistical. But there are
always theories about socioeconomic factors [that lead people to become
addicted to cigarettes] and other things that play in. That's why
we went to the animal studies. They're all living in the same tenement.
We are trying to establish a biological basis for that statistical
Slotkin's team administered nicotine or a placebo to pregnant rats.
Then, their offspring got a secondary exposure to nicotine or a placebo
during their "preteen" or "teen" years.
Nicotine mimics the action of acetylcholine, a chemical brain messenger
that plays a crucial role in learning and memory, Slotkin explained.
"The way those pathways are affected, if you administer nicotine
[later], you restore function," he said.
That might explain why some teens seem to get hooked on tobacco after
only a few cigarettes, Slotkin said. They may have been exposed in
the womb and are trying to compensate for the damage in the brain
circuits that control memory, learning and mood.
The new study adds to a growing body of research about what happens
to the offspring of smokers, said Dr. Joseph DiFranza, a professor
of family medicine at the University of Massachusetts who researches
It's long been known, he said, that "children of women who smoke
have behavioral problems" compared with those whose mothers don't
smoke. Experts have wondered if the children just inherit some of
the same genes or if nicotine exposure in utero might play a role.
Slotkin's study demonstrates that there may be structural damage to
the brain that persists in offspring of women who smoke during pregnancy,
The research by Slotkin "may help to explain why children of
smokers are particularly prone to use tobacco products," added
Neil Grunberg, a professor of medical psychology, clinical psychology,
and neuroscience at the Uniformed Services University in Bethesda,
"Although these studies are done in a rat model, the findings
are likely to generalize to humans," he said. "If so, then
pregnant women should be advised that smoking during pregnancy may
increase the likelihood that their children will smoke later in life
and also may have long-term biological actions in these offspring."
Despite the fact that there has been a drop in maternal smoking in
recent years, the researchers noted that about 25 percent of Americans
have mothers who smoked during pregnancy.
For more information on maternal smoking and its adverse effects,
visit the National Institute on Drug Abuse (www.drugabuse.gov
). For information on teen smoking, visit the American Cancer
Society (www.cancer.org ).