Children exposed to alcohol during fetal development exhibit changes in brain structure and metabolism that are visible using various imaging techniques, according to a new study being presented today at the annual meeting of the Radiological Society of North America (RSNA).
Alcohol use by expectant mothers can lead to problems with the mental and physical development of their children—a condition known as fetal alcohol syndrome. Research suggests an incidence of 0.2 to 1.5 per 1,000 live births, according to the Centers for Disease Control and Prevention. Costs for care of individuals affected by fetal alcohol syndrome in the U.S. have been estimated at $4 billion annually. Advancements in magnetic resonance imaging (MRI) are affording unprecedented insights into the effects of alcohol on the central nervous systems of children whose mothers drank alcohol during their pregnancy. Recently, researchers in Poland used three different MRI techniques to better define these effects.
The study group included 200 children who were exposed to alcohol during their fetal stage and 30 children whose mothers did not drink while pregnant or during lactation. Researchers used MRI to evaluate the size and shape of the corpus callosum, the bundle of nerve fibers that forms the major communication link between the right and left halves of the brain, in the two groups. Prenatal alcohol exposure is the major cause of impaired development or complete absence of the corpus callosum.
The MRI results showed statistically significant thinning of the corpus callosum in the children exposed to alcohol compared with the other group.
“These changes are strongly associated with psychological problems in children,” said Andrzej Urbanik, M.D., chair of the Department of Radiology at Jagiellonian University in Krakow, Poland.
Dr. Urbanik and colleagues also used diffusion weighted imaging (DWI) to study six areas of the central nervous system in the children. DWI maps the diffusion process of water and can be a more sensitive means than traditional MRI for detecting tissue abnormalities.
Children in the alcohol group exhibited statistically significant increases in diffusion on DWI compared with the other children.
“The increase of diffusion indicates neurological disorders or damage to the brain tissue,” Dr. Urbanik said.
To noninvasively study metabolism in the brains of the children, the researchers used proton (hydrogen) magnetic resonance spectroscopy (HMRS), a common adjunct to structural MRI studies. HMRS results showed a complex collection of metabolic changes.
“In individual cases, we found a high degree of metabolic changes that were specific for particular locations within the brain,” Dr. Urbanik said.
Seems like some fishy surrogate endpoints. One would like to know whether the kids whose mothers drank actually had any more “psychological problems”. Surely a survey of that issue would have been cheaper and less intrusive for the healthy kids being subjected to study. If the researchers are going to confine themselves to waving statistical differences in minute anatomical features around luridly, then one would like to know whether or not the statistically significant difference was even potentially clinically significant. Was the difference driven primarily by tiny and almost certainly irrelevant variations from the alleged norm in many children, or large differences in a few? If the latter, one would like parental drinking histories so one knew whether the serious outliers were all the children of women who drank heavily, which is already well known to be capable of causing neurological damage.
One would also like to have equal or sorta-equal sample sizes, instead of 200 vs. 30. 30 is too small a group to show the range of natural human variation or even be confident that you’ve approached the “true mean”, and if you measure any number for groups of such disparate size, the observed range of variation will almost always be broader in the larger group. This raises concerns that the researchers deliberately used a tiny number of teetotalers’ kids so that it would be certain that many of the drinkers’ kids would fall outside their alleged normal range, and not unlikely that they might skew towards one end of that distribution, just by chance. Teetotaling mothers may also differ from drinking mothers in education, socioeconomic status, intelligence, or conscientiousness; the groups of mothers might themselves have minute average differences in “brain structure”, which might be heritable and/or affected by child-rearing practices. Was any effort whatsoever made to correct for that? Hard to do so when 30 mothers cannot possibly represent as much of the social spectrum as 200 mothers.