18 November 2002
by INGRID HOLMES
A new animal study hints
that even a little alcohol during pregnancy may affect a baby's brain. A group of adult rats flunked a navigation
test1. Their mothers had consumed
quantities of alcohol while pregnant that were analogous to one drink a day for
a human during the first six months.
Britain's Royal College of
Obstetricians and Gynaecologists advises pregnant women to limit their daily
alcohol intake to one small glass of wine or beer or a measure of spirits. This is to reduce the risk of fetal alcohol
syndrome - the learning and behavioural difficulties seen in children whose
mothers drank heavily throughout pregnancy.
The rodent research, carried
out by Daniel Savage and colleagues from the University of New Mexico Medical
School, suggests that there may be more subtle effects of low-level alcohol
intake that become obvious only later in life, as more complex tasks are taken
on.
"Behavioural deficits
appeared in rats that are relevant to humans," says psychologist Charles
Goodlett of Indiana University-Purdue University, Indianapolis. But, he warns, "there is an enormous
step between the gestation periods of rats and humans, so we must be careful
about extrapolating the data too much".
Savage and his colleagues
also found altered levels of glutamate in their rats. Levels of this key messenger molecule were one-third lower than
normal in the hippocampus, the brain region that is responsible for learning
and memory.
We must be careful about
extrapolating too much from rat data Charles Goodlett IUPU
So how much alcohol is
safe? "We really don't know the
magic number," says Savage.
"In the absence of definitive information, it is better to
abstain," he says. "Why take
a chance?"
Neurologist Michael Charness
at Harvard Medical School agrees.
"For every kid with fetal alcohol syndrome, there are another ten
who have been exposed to alcohol, have no obvious physical defects but do have
cognitive problems." The rat results are striking and not entirely
surprising, he says.
References Savage, D. D., Becher, M., de la Torre, A. J.
& Sutherland, R. J. Dose-dependent effects of prenatal ethanol
exposure on synaptic plasticity and learning in mature offspring. Alcoholism: Clinical and Experimental
Research, 26, 1752 - 1758, (2002).
Abstract:
http://ipsapp002.lwwonline.com/content/getfile/88/76/20/abstract.htm
© Nature News Service /
Macmillan Magazines Ltd 2002
http://www.nature.com/nsu/021111/021111-15.html