IOWA CITY, Iowa -- Fetal alcohol syndrome in affected people has been associated with mental retardation and a smaller or nonexistent corpus callosum. The callosum is a major brain pathway that coordinates input from one side of the brain to the other to help provide unified sense perception. However, a study led by a University of Iowa Health Care researcher suggests that moderate (versus severe) alcohol overexposure can cause the corpus callosum to be larger than normal.
"Previous research showed that the corpus callosum is very small or even nonexistent in people with fetal alcohol syndrome," said Michael W. Miller, Ph.D., UI professor of psychiatry and pharmacology, and a career research scientist at the Iowa City Veterans Affairs Medical Center. "But this human data was quite at odds with other studies, including one at the UI involving rats, which showed maternal alcohol intake can increase the number of cells contributing connections passing through corpus callosum in offspring."
The contradiction motivated Miller and two University of Washington researchers to investigate how fetal alcohol syndrome affects the corpus callosum in macaques, primates that closely resemble humans. The team analyzed 15 post-puberty macaques affected to varying degrees by maternal alcohol consumption during gestation. The findings were published in the September 13 issue of the Journal of Comparative Neurology.
Using magnetic resonance imaging (MRI) and post-mortem analyses, the team found
that offspring of macaque mothers fed 170 - 270 milligrams (mg) of alcohol per
deciliter of blood (sufficient to bring blood alcohol concentrations to .17 to
.27 mg percent) for several weeks or months had more axons in their corpus
callosums than did control animals. These axons conduct signals from one side of
the brain to the other. In contrast, Miller said, the research on humans
affected by fetal alcohol syndrome was generally based on extreme cases in which
the mothers' b
Contact: Becky Soglin
University of Iowa