Female toddlers whose mothers had high levels of cortisol during pregnancy are more likely to display anxious and depressive-like behaviors, according to a new study published in the journal Biological Psychiatry.
Often called the “stress hormone,” cortisol is a steroid produced in the adrenal glands. Not only does it help manage stress, but it also helps regulate blood sugar levels, metabolism, inflammation and memory formulation.
Based on brain scans taken first as newborns and again at two years old, high levels of maternal cortisol and resulting mood symptoms in the toddlers were linked to altered activity in the amygdala, a brain region associated with sensory and emotion processing.
The findings reveal a potential pathway through which the prenatal environment may predispose females to developing mood disorders.
“Higher maternal cortisol during pregnancy was linked to alterations in the newborns’ functional brain connectivity, affecting how different brain regions can communicate with each other,” said senior author Claudia Buss, Ph.D., of Charité University Medicine Berlin and University of California, Irvine.
Interestingly, male toddlers of mothers with high cortisol during pregnancy did not demonstrate stronger brain connectivity or a connection between maternal cortisol and mood symptoms.
“Many mood and anxiety disorders are approximately twice as common in females as in males. This paper highlights one unexpected sex-specific risk factor for mood and anxiety disorders in females,” said John Krystal, MD, Editor of Biological Psychiatry. “High maternal levels of cortisol during pregnancy appear to contribute to risk in females, but not males.”
The new study measured the mothers’ cortisol levels during pregnancy in a more comprehensive manner than had been done in previous research, according to first author Alice Graham, Ph.D., of Oregon Health & Science University.
The researchers measured the hormone in 70 women over multiple days in early-, mid-, and late-pregnancy. The findings reflected typical variations in maternal cortisol levels.
Next the team used brain imaging to examine brain region connectivity in the babies soon after they were born — before the external environment had begun shaping brain development. Then they measured the children’s anxious and depressive-like behaviors at two years of age.
The researchers discovered altered connectivity in the amygdala, a brain region important for emotion processing. This pattern of brain connectivity predicted anxious and depressive-like symptoms two years later.
The findings support the idea that maternal stress may alter brain connectivity in the developing fetus, which would mean that vulnerability for developing a mood disorder may begin prior to birth. This time period could be an early point at which the risk for common psychiatric disorders begins to differ in males and females.