NARSAD Grantees from the University of California-Davis (UC-Davis) MIND Institute discovered that specific combinations of antibodies cross the placenta during pregnancy, contributing to altered brain development and behavioral patterns associated with autism. The researchers are calling this form of autism "maternal antibody-related (MAR) autism" and say that it could represent as much as 23 percent of all autism cases. According to the U.S. Centers for Disease Control about 1 in 88 children has an autism spectrum disorder (ASD).
The study authors were Brain & Behavior Research Foundation NARSAD Grantees Melissa Bauman, Ph.D. (lead researcher), Paul Ashwood, Ph.D. and David G. Amaral, Ph.D. (senior author) and other UC-Davis colleagues across the disciplines of immunology, animal behavior and neuroscience. They furthered work from previous studies to more clearly understand the role of prenatal exposure to immunoglobulin-G (IgG) autoantibodies in rhesus monkeys. The findings were published in the Nature journal Translational Psychiatry on July 9, 2013.
The study looked at three groups of pregnant non-human primates; a group of mothers given IgG antibodies during pregnancy from mothers of typically-developing children; a group given IgG autoantibodies during pregnancy from mothers of children who show signs of autism; and a control group that did not receive antibodies. The scientists examined the social interactions of the mothers and infants and reviewed longitudinal magnetic resonance imaging (MRI) scans of the offsprings’ brains. Offspring exposed in utero to the IgG autoantibodies had atypical social interactions compared to peers and the brains of males from that group were larger than their male peers from other groups.
The mothers of the atypically-developing group were more protective of their offspring. Dr. Bauman, UC-Davis Assistant Adjunct Professor, Department of Psychiatry and Behavioral Sciences, and MIND Institute, says that these mothers may detect subtle behavioral abnormalities in their young. "The heightened protectiveness of the monkey mother's was observed only when other animals were present, suggesting that the mothers perceived a greater risk to their IgG-ASD treated infants...this is a very promising avenue of research."
David Amaral, Research Director, MIND Institute noted "that much research remains ahead of us to identify the mechanisms by which the antibodies affect brain development and behavior. But, this program of research is very exciting, because it opens pathways to potentially predicting and preventing some portion of future autism cases."