Grey matter differs in women experiencing pregnancy-related depression, depressive disorder: study

Brain scans have revealed differences in grey matter between women experiencing post-pregnancy depression and those suffering from major depressive disorder, according to a study.

The study, published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, provides a biological basis for why post-pregnancy, or peripartum, depression should be considered separate from depression, which can occur at any time, including after giving birth.

In both the conditions, losing interest in activities once found enjoyable is common. However, postpartum depression can include symptoms related to becoming a mother, such as sleep problems, guilt, and worrying about the baby.

Researchers analysed MRI brain scans of 64 women with major depressive disorder, who either had a history of post-pregnancy depression or did not, to identify grey matter differences.

“We found bilateral grey matter clusters within the basal ganglia (in the cerebrum), an area crucial for motivation, decision-making, and emotional processing, to be larger in women with a history of peripartum depression, compared to women who have only experienced depressive episodes outside of this time period,” first author Yasmin A. Harrington, a PhD candidate at the Vita-Salute San Raffaele University, Milan, Italy, said.

The researchers explained that the involvement of sex hormones is often thought to distinguish post-pregnancy depression from major depressive disorder.

Previous studies have found that women experiencing the post-pregnancy condition are especially sensitive to sharp rises and falls in the levels of the hormones estradiol and progesterone.

Sex hormones have also been studied to significantly affect brain structure and function, thereby impacting a mother’s behaviour.

“We were surprised that the effect of peripartum depression could be seen years after the episode, suggesting that these differences are related to the neurobiology of the disorder rather than to the specific episode,” Harrington said.

Scores reflecting a mother’s genetic sensitivity towards estradiol levels were calculated to see if they impacted their brain differently based on a history of peripartum depression, lead researcher Francesco Benedetti, a professor of psychiatry at Vita-Salute San Raffaele University, explained.

“Our findings show that estradiol genetic scores had a positive effect on basal ganglia volumes in women with peripartum depression and a negative effect in women without peripartum depression, suggesting a differential effect of the genetic load from estradiol on brain structure based on history of peripartum depression,” Benedetti said.

“Our findings demonstrate that women who have experienced a peripartum episode are neurobiologically distinct from women who have no history of postpartum depression in a cluster within the basal ganglia, an area important for motivation, decision making, and emotional processing,” the authors wrote.