Is There a Link Between Prenatal Alcohol Exposure and ADHD?
Nov. 15, 1999 (Tuscaloosa, Ala.) -- A study funded by the National Institute
on Alcohol Abuse and Alcoholism (NIAAA) may have found a common pathway to
explain the similarities between two childhood conditions -- attention deficit
hyperactivity disorder (ADHD) and fetal alcohol syndrome (FAS).
Prenatal exposure to alcohol has long been known to cause mental retardation
and has previously been linked to ADHD. The current study shows that rat pups
exposed to alcohol while in their mother's wombs have less activity in their
brains of a chemical transmitter called dopamine.
Our brains are composed of billions of nerve cells called neurons. We are
able to think and act because those neurons communicate with each other by way
of chemical messengers called neurotransmitters. Dopamine is one of those
The study, by Roh-Yu-Shen, PhD, senior scientist at the State University of
New York at Buffalo, involved giving pregnant rats varied doses of alcohol
during pregnancy. Shen and her research team found that the alcohol-exposed rat
pups had 50% decreases of the activity of dopamine neurons in their brains.
Furthermore, the decrease persisted as the pups matured into adult rats.
"This is a very interesting finding within a very important field of
study," says Jaime L. Diaz-Granados, assistant professor at Baylor
University. "The finding has serious implications for both children with
FAS-induced ADHD as well as those children whose ADHD is not FAS induced. For
the later group, we may find there are some dopamine abnormalities underlying
The implication is that new drugs might be developed to help children with
this disorder. "We have no treatment for children with fetal alcohol
syndrome and we certainly need one," Kenneth Jones, MD, the researcher who
first discovered FAS, tells WebMD. "If this decrease in the number of
dopamine neurons in rat pups with fetal alcohol syndrome also occurs in human
children, then a drug ... could be developed and might be helpful in treating
these kids." Jones is a professor of pediatrics at the University of
California, San Diego.
"Understanding how fetal alcohol exposure can contribute to ADHD allows
us to understand the cellular mechanism of what's happening in the brain,"
Shen says. "We need to understand how to restore dopamine activity. We
already know that stimulants like Ritalin can restore deficits in dopamine
systems. Now we need to fine-tune that strategy in terms of different drugs and
Jerry Sells, MD, professor of pediatrics at Oregon Health Sciences
University School of Medicine, has misgivings about that claim. "It is a
big leap of faith to take anything we see in the rat model and apply it to what
we see in children. We should be cautious using stimulant drugs on FAS
"The ADHD symptoms that we see in FAS kids may not even be caused by the
same basic mechanisms," Sells tells WebMD. "There are lots of
neurotransmitters in the brain. I don't necessarily agree that the ADHD that we
see in fetal alcohol syndrome kids is totally equivalent to the ADHD that we
see in non-fetal alcohol kids. Both groups have some of the same symptoms, but
they are not identical syndromes.
"Ritalin, for example, which helps many ADHD kids control their
hyperactivity and concentrate, doesn't seem to be all that useful for FAS
patients," continues Sells. "We may, indeed, be looking at some kind of
common pathway but, because these were rat experiments, we're not sure that
things happen in the same way in humans."