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:
© Nature News Service / Macmillan Magazines Ltd 2002