Inflammatory Marker Associated with Newborn Amygdala

Maternal inflammation during pregnancy increases the risk for offspring psychiatric disorders and other adverse long-term health outcomes. While changes in the expression of inflammatory markers during a woman's pregnancy may be linked to infection, they can also be associated with other conditions, such as obesity or psychological stress.

Increased levels of inflammatory markers during pregnancy can lead to changes in fetal brain development which, in turn, may increase the child's risk of developing psychiatric disorders. The incidence of impaired impulse control, the cardinal symptom of these disorders, appears to be particularly affected by this increase in maternal inflammation.

An international team of scientists led by those at the Charité University of Medicine Berlin (Germany) recruited a total of nearly 90 women in the first trimester of pregnancy and their infants were followed up serially until the age of 24 months. The participating women and their unborn children underwent three examinations, one in each of the three trimesters of pregnancy. In addition to carrying out ultrasound examinations and the analysis of biological samples, the team also recorded potential medical complications, as well as the psychological wellbeing of the mothers.

The investigators found higher average maternal interleukin-6 (IL-6) concentration during pregnancy was prospectively associated with larger right amygdala volume and stronger bilateral amygdala connectivity to brain regions. These regions are involved in sensory processing and integration (fusiform, somatosensory cortex, and thalamus), salience detection (anterior insula), and learning and memory (caudate and parahippocampal gyrus). Larger newborn right amygdala volume and stronger left amygdala connectivity were in turn associated with lower impulse control at 24 months of age, and mediated the association between higher maternal IL-6 concentrations and lower impulse control.

The authors concluded that their findings provide new evidence in humans linking maternal inflammation during pregnancy with newborn brain and emerging behavioral phenotypes relevant for psychiatric disorders. Claudia Buss, a professor of Medical Psychology and senior author of the study said, “We discovered that higher levels of interleukin-6, an inflammatory marker, were associated with changes in the neonatal amygdala in terms of its anatomy and connectivity. Furthermore, our subsequent findings showed that these changes were also associated with lower impulse control at two years of age.” The study was published originally online on June 9, 2017, in the journal Biological Psychiatry.

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Charité University of Medicine Berlin