Postnatal depression affects about one in seven women giving birth, but little is known about what happens in the brains of pregnant women experiencing it. New research begins to shed some light.
Researchers scanned the brains of dozens of women around the weeks of childbirth and found that two brain regions involved in emotional processing and control increased the size of women who developed symptoms of postpartum depression.
The results published in Science Advances on Wednesday constitute some of the first evidence that postpartum depression is linked to changes in the brain during pregnancy.
The researchers found that women with symptoms of depression in the first month after birth also increase the amount of the amygdala, a brain region that plays an important role in emotional processing. Women who rated the experience of childbirth as difficult or stressful – often associated with postpartum depression – also showed an increase in the amount of hippocampus, a brain area that helps regulate emotions.
“This is the first step in trying to understand how the brains of people who have a normal course of pregnancy and those experiencing perinatal depression change and what can be done about it,” said Dr. Sheila Shanmugan, an assistant professor at the University of Pennsylvania, an assistant professor in psychiatry, obstetrics and gynecology.
“The big point is how these really deep brain changes are during pregnancy and now we are seeing them in particular in the depression circuit,” she said.
This study was conducted in Madrid by a team leading an effort to document the effects of pregnancy on the brain. This is part of many studies that have found that certain brain networks, particularly those involved in social and emotional processing, can shrink during pregnancy and undergo fine-tuned processes to prepare for parenting. These changes correspond to a surge in pregnancy hormones, particularly estrogen, which researchers discovered at least two years after giving birth.
The new study appears to be the first to compare changes in postnatal depression by scanning and comparing brain regions during and after pregnancy, said Elserin Hockesema, a neuroscientist who heads the Institute for Pregnancy and Brain at the University of Amsterdam Medical Center and a neuroscientist who was not involved in the study.
The study authors and other researchers said it is not clear whether increased amygdala and hippocampus volume caused perceptions of depressive symptoms and stress during childbirth, or whether brain changes occur in response to symptoms and stressors. Also, brain scans revealed why some women seemed more vulnerable to these symptoms than others.
“Those who are prone to changes in the amygdala may be at a higher risk of suffering from postnatal depression,” said Susana Carmona, a senior author of the study, who is a neuroscientist who leads the neuroprimary lab at the lab destivatuciónsanitaria gregoriomarañón in Madrid. “It could also be another way,” she said.
Researchers have studied 88 pregnant women who had not given birth before and have no prior history of depression or other neuropsychiatric symptoms. In the control group, they also saw 30 women who were not pregnant. Pregnant women had brain scans during their third trimester and approximately one month after birth.
Women completed standard surveys to assess whether they had symptoms of postpartum depression. After giving birth, 15 women showed moderate symptoms of depression, while another 13 women showed symptoms of depression so severe that they would guarantee they would seek medical assistance, Dr. Carmona said.
Women also completed a survey on whether they perceived difficulties in having a childbirth. Previous studies have shown that “negative birth experiences are associated with increased depression scores,” Dr. Carmona said. She said that difficult birth experiences are not necessarily medically challenging delivery, but could be simple delivery that women perceived as stressed due to factors like rude hospital staff.
Laura Plitchet, a postdoctoral psychiatry scholar at the University of Pennsylvania, called the results “really fascinating,” adding that he “trys to further study what areas of the brain are trying to grasp what areas.”
Dr. Pritschet wrote an article with Dr. Shanmugan in the same issue of a journal advocating for research to determine personalized brain signatures for perinatal depression, saying the discoveries of the new research will ultimately help identify roadmaps to improve prediction, diagnosis and treatment of postnatal depression.
“What do we do if we routinely show that certain brain regions are involved? How can we intervene quickly?” she said. “What is the normal amount of change? Why is the area vulnerable? There are many interesting questions to ask next.”
