The researchers also found a reduction in brain activity that was associated with greater impairment of maternal attachment processes.
“The birth of a child is a greatly anticipated and desired life event, but it is paradoxically accompanied by maternal depression in 15 percent of new moms,” said Eydie L. Moses-Kolko, M.D., lead author of the study and assistant professor of psychiatry at Pitt. “With our research, we are hoping to gain greater mechanistic understanding of postpartum depression, namely what is going on in the brains of depressed mothers.”
For the study, researchers compared 14 depressed and 16 healthy mothers, all of whom delivered a healthy term infant in the preceding 12 weeks, were medication-free and had previously given birth to another child. Mothers were assessed using functional MRI to look at brain activity in relationship to prenatal depression, anxiety and function, as well as with a questionnaire to determine attachment quality, hostility and pleasure in interaction with their infants.
To fully engage the brain regions involved in emotion processing, the researchers used a well-known face-matching test. The mothers were shown images of angry and scared faces, and the researchers examined their neural reactions to the images. Researchers found that negative emotional faces activated the left dorsomedial prefrontal cortex, which is a social cognition region of the brain, significantly less in depressed mothers than in healthy mothers. Deficits in this region, therefore, might represent diminished awareness of the emotions of others and less empathy for them. The researchers also found that while negative images were viewed, communication between the left dorsomedial prefrontal cortex and the left amygdala was present in healthy moms but not in the depressed ones, suggesting that this might be an important neural circuit that regulates emotional response to unpleasant stimuli, such as a crying baby.
“We also discovered that greater infant-related hostility and more severe depression were associated with reduced face-related amygdala activity, which may be a mechanism for the reduced attunement and empathic responses in some depressed moms that is described in the literature,” noted Dr. Moses-Kolko. “We need studies whereby brain responses can be directly related to live mother-infant behavior in order to definitely clarify brain mechanisms of mother-infant attachment. Ultimately, this information has the potential to guide the development of more effective treatments for postpartum depression.”
Co-authors of the study include Susan B. Perlman, Ph.D., Katherine L. Wisner, M.D., M.S., Jeffrey James, A. Tova Saul, and Mary L. Phillips, M.D., all from the University of Pittsburgh School of Medicine’s Department of Psychiatry.
This study was supported in part by funding provided by the National Institute of Mental Health and the National Alliance for Research on Schizophrenia and Depression (NARSAD).
Western Psychiatric Institute and Clinic (WPIC) is considered to be one of the nation’s foremost university-based psychiatric care facilities and one of the world’s leading centers for research and treatment of mental health disorders. WPIC houses the Department of Psychiatry of the University of Pittsburgh School of Medicine and is the flagship of UPMC Behavioral Health, the psychiatric specialty division of UPMC (University of Pittsburgh Medical Center).