Prolactin mediates the relationship between regional gray matter volume and postpartum depression symptoms

Pospartum Depression (PPD) causes significant adverse effects on mothers and their offspring. The condition is considered to have multiple pathogenic factors. However, the underlying neural basis of these factors keeps unclear.

A group of 86 patients with PPD and 74 Healthy Postnatal Women (HPW) were enrolled in this structural Magnetic Resonance Imaging (MRI) study. Between-groups differences in regional gray matter volume (rGMV) were measured and association and mediation analyses were performed to investigate the relationship between rGMV, PPD severity and a range of demographic/clinical factors which could contribute to PPD.

Relative to HPW, PPD patients had higher scores indicating adverse effects on most questionnaires and higher prolactin levels, as well as increased rGMV in left dorsolateral prefrontal cortex (DLPFC) and right anterior insular (anI). In PPD patients, rGMV in right anI was positively correlated with prolactin level, PPD severity, and the number of children raised, whereas rGMV in left DLPFC was negatively correlated with education and age. Besides, prolactin level was found to mediate the association between rGMV in anI and PPD symptoms.

Potentially factors such as fertility or delivery pattern were not studied.

Our results provide information on the risk and protective factors, and rGMV abnormalities, associated with PPD. The finding that prolactin level mediated the impact of rGMV in right anI on PPD symptoms is a potential mechanism for explaining the association between brain structure and PPD symptoms. Increased understanding of the neuro-pathophysiology of PPD is important for early diagnosis and treatment.