Birth represents a time of celebration, beginnings, and, for 10 to 15% of new mothers, the onset of postpartum depression (PPD) [1,2,3]. PPD is considered a subset of major depressive disorder (MDD). It creeps up on the postpartum mother in waves of sudden sadness or disinterest. As if recovering from pregnancy isn’t exhausting enough, symptoms such as unusual appetites, irregular sleep patterns, and struggling to concentrate overtake these new mothers’ lives. PPD can also add additional layers of fatigue, anxiety, and irritability to new mothers’ everyday lives [2,4]. To be officially diagnosed with PPD, the postpartum mother must exhibit these symptoms for at least two weeks. 

If left untreated, postpartum depression can make bonding between a mother and her child difficult, which can increase risks for poor cognitive and motor development in the child. These can further lead to lower self-esteem and poor self-control, among other health problems later in life [2,5]. With untreated PPD, mothers are at greater risk for chronic or recurrent depression [2]. PPD can be hard to identify correctly, due to the variety of lifestyle changes and confounding symptoms that nearly all new parents experience. There is a vast range of PPD symptoms, which are often confused with other conditions, two examples of which include: adjustment disorder and a more common condition known as “postpartum blues,” or “baby blues.” 

Distinguishing Between Conditions

Baby blues refer to the unexpected feelings of sadness that 50 to 85% of new mothers feel in the first few days after giving birth [1,2]. Adjustment disorder, on the other hand, is not specific to the postpartum period, but may arise shortly after delivery [6]. Mothers with adjustment disorder may undergo symptoms of distress and anxiety, as well as difficulty sleeping, eating, or executing everyday tasks, in response to a clear stressor (in this case, giving birth). In adjustment disorder, symptoms begin within three months postpartum [1,6]. 

The major difference between postpartum depression and the baby blues is that baby blues tend to disappear a few days after childbirth, and usually do not involve suicidal ideation (Table 1) [1]. Adjustment disorder, on the other hand, can drag on for up to three months, but the severity of its symptoms do not meet the criteria for clinical depression, where those of PPD do [1]. Additional symptoms of PPD share similarities with those of postpartum psychosis and major depressive disorder [1]. Postpartum psychosis is prevalent two weeks after delivery and carries the critical risks of infanticide and suicide, making it a life-threatening state for both the new mother and her baby [2]. Unlike postpartum depression, postpartum psychosis is hallmarked by delusions, hallucinations, and confusion, and is considered an extension of bipolar disorder [4]. 

There are fewer distinctions between postpartum depression and major depressive disorder, as postpartum depression is a subset of major depressive disorder and they share major risk factors and etiology [2,3]. PPD may also be distinguished by onset time: early or late. Early-onset PPD occurs within a 4 week postpartum time frame, and as a hormone-sensitive form of PPD, it differs from the later-onset form, which is more psychosocially involved [1]. The DSM-5—a go-to manual for identifying mental disorders—classifies only the early-onset form as real PPD and the later form, instead, as MDD [1,6]. Some symptoms of postpartum depression—such as losing sleep and hormonal changes—are experienced by most new parents to different degrees, which limits new mothers’ abilities to determine whether they are experiencing symptoms of PPD [2].

Screening

Roughly 50% of postpartum depression cases fail to be properly identified [1,3]. This statistic highlights the importance of proper and widespread screening for PPD. PPD screening is often done via self-reporting questionnaires, which healthcare providers may ask new mothers to fill out [6,7]. PPD is most commonly screened through three clinical assessments: the Bromley Postnatal Depression Scale (BPDS), the Edinburgh Postnatal Depression Scale (EPDS), and the Postpartum Depression Screening Scale (PDSS) [3]. However, other major screening tests for depression and health are also commonly used to identify PPD [2,3]. The purpose of these assessments is to perinatally (before, during, and after pregnancy) examine the mother’s psychiatric history and life events to identify risk factors and depression [7]. 

Of the major assessments, particular tests are more suited for reporting in specific groups, such as for people from different cultures and with different levels of education [3]. PPD-specific tests may also be used in conjunction with general patient health questionnaires for more detailed or accurate screening [3]. The most researched and widely used PPD screening assessment is the Edinburgh Postnatal Depression Scale (EPDS) [2,3]. The EPDS measures emotional and cognitive PPD symptoms from 10 items, scored 0 to 3. The cutoff for positive screening (indicative of PPD) is set at more than 13 out of 30 points [2,3]. However, the EPDS, alongside other assessments, experiences a large amount of false positives [3]. To resolve this urgent challenge in detecting PPD, scientists seek to identify additional risk factors and predictors among new mothers [1,2,7]. No single, infallible predictor of PPD currently exists [7]. In an attempt to discover a universal predictor, a wide range of factors—from genetics, demographics, social support, life and health history, all the way down to molecular predictors—have been examined. To some avail, risk factors such as genetics, psychiatric history, and social support prove to be more reliable indicators. Yet, there are many risk factors riddled with mixed levels of PPD association (Table 2) [7]. Beyond these risk factor analyses, scientists are also using multimodal neuroimaging to look at structural and functional distinctions in the brains of patients with PPD, as imaging has been used to identify structural and functional abnormalities for MDD [1]. Multimodal neuroimaging refers to combining many different techniques of neuroimaging to make up for the limitations of each individual technique and to paint a fuller picture of brain processes [8]. A common instance of multimodal imaging is found in the combination of electroencephalography (EEG), a passive electrophysiological recording method that measures brain waves, with fMRI, which measures changes in blood flow during brain activity [9].

Neuroimaging 

In a recent study published by Scientific Reports in June 2021, postpartum women were monitored for 12 weeks [1]. They underwent psychiatric diagnoses, the EPDS, and resting state functional magnetic resonance imaging (rsfMRI, a type of fMRI that focuses on brain processes when no explicit tasks are being performed) to determine early changes in brain structure and function due to PPD [1]. The 157 recruited women had no clinical depression at the time of recruitment, and were between 18 and 45 years old. Patients with severe pregnancy- or birth-related complications, substance dependency, and a history of psychosis were excluded from the study [1]. 

Women diagnosed with postpartum depression, adjustment disorder, or deemed healthy controls were distinguished from each other. The risk factors: severity of baby blues, severity of premenstrual syndrome (PMS), and psychiatric history were used to distinguish new mothers with PPD from those with AD, as both were present in the group [1]. The researchers found a prevalence of 13.4% PPD and 12.1% adjustment disorder among the women [1]. Women diagnosed with adjustment disorder and PPD were found to score higher on the EPDS than healthy control women, over a 12-week monitoring period, starting at time T0 and ending at T4 (Table 3) [1]. The T4 EPDS scores for women with adjustment disorder came to a mean value of 5.68, while for women with PPD the mean was 13.55 and for healthy controls, it was 2.55 (Table 3) [1]. Here, we see that EPDS scores were highest for women experiencing PPD and AD, and multitudes lower for the healthy controls. The women with PPD and adjustment disorder were more likely to exhibit a psychiatric history and more severe baby blues than their healthy counterparts [1]. 

On the neuroimaging front, resting state functional magnetic resonance imaging analyses found no significant differences between the brains of women with PPD, adjustment disorder, and the brains of healthy control women. The purpose of rsfMRI in this study was to identify differences in interactions between the brains of new mothers who were and were not diagnosed with PPD. The expected adaptive changes in the brain that commonly affect brain structure in pregnant and postpartum women were observed, but with no significant difference between women with PPD and without [1]. Yet, one area of the brain, the left superior medial frontal gyrus,which is involved in movement and decision-making, showed notable changes in brain function that correlated with higher EPDS scores, toward the end of the study (Figure 1) [1]. This correlation could be a potential marker for depression, but, as it could only be identified late in the study, it cannot be used as a predictor for PPD [1]. Otherwise, no other significant associations were found between rsfMRI analyses and the risk profiling measures. One possible explanation for the lack of differences in imaging results taken earlier in the study was that the participants were not depressed at the time of imaging [1]. Compared to previous studies that reported PPD alterations in brain connectivity, the current study has a larger sample size and selected for onset time of PPD [1]. In literature, participants who were already 8 to 12 weeks postpartum had been recruited for PPD studies, which is 1-2 months too late to study early-onset PPD [1]. In contrast, the current study standardized PPD onset times, to avoid missing early changes in the brain or cause confusion between early- and late-onset PPD cases [1]. 

The study concludes that no significant structural and functional neuroimaging differences were found between PPD, adjustment disorder, and healthy controls from rsfMRI data [1]. Although multimodal neuroimaging is not currently revealing predictors for PPD, it remains a highly useful tool for studying disorders that affect the brain [1]. However, in order to find a consistent and timely way to identify and alleviate the symptoms of women with PPD, and to protect their children, the search for a universal predictor of PPD continues.

References

1. Schnakenberg, P., Hahn, L., Stickel, S., Stickeler, E., Habel, U., & Eickhoff, S. et al. (2021). Examining Early Structural and Functional Brian Alterations in Postpartum Depression Through Multimodal Neuroimaging. Scientific Reports, 11(1). https://doi.org/10.1038/s41598-021-92882-w.
2. Patel, M., Bailey, R., Jabeen, S., Ali, S., Barker, N., & Osiezagha, K. (2012). Postpartum Depression: A Review. Journal Of Health Care For The Poor And Underserved, 23(2), 534-542. https://doi.org/10.1353/hpu.2012.0037.
3. Boyd, R., Le, H., & Somberg, R. (2005). Review of screening instruments for postpartum depression. Archives Of Women’s Mental Health, 8(3), 141-153. https://doi.org/10.1007/s00737-005-0096-6.
4. Sit, D., & Wisner, K. (2009). Identification of Postpartum Depression. Clinical Obstetrics & Gynecology, 52(3), 456-468. https://doi.org/10.1097/grf.0b013e3181b5a57c.
5. Field, T. (2010). Postpartum depression effects on early interactions, parenting, and safety practices: A review. Infant Behavior And Development, 33(1), 1-6. https://doi.org/10.1016/j.infbeh.2009.10.005.
6. American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596.
7. Guintivano, J., Manuck, T., & Meltzer-Brody, S. (2018). Predictors of Postpartum Depression: A Comprehensive Review of the Last Decade of Evidence. Clinical Obstetrics & Gynecology, 61(3), 591-603. https://doi.org/10.1097/GRF.0000000000000368.
8. Tulay, E. E., Metin, B., Tarhan, N., & Arıkan, M. K. (2018). Multimodal neuroimaging: Basic concepts and classification of neuropsychiatric diseases. Clinical EEG and Neuroscience, 50(1), 20-33. https://doi.org/10.1177/1550059418782093.
9. Uludağ, K., & Roebroeck, A. (2014). General overview on the merits of multimodal neuroimaging data fusion. NeuroImage, 102, 3-10. https://doi.org/10.1016/j.neuroimage.2014.05.018.