Peripartum depression (PPD) is a mood disorder with symptom onset during pregnancy and up to four weeks after childbirth and is reported in 15-20% of pregnant women worldwide. Depressive symptoms can range from mild mood changes to severe depression with suicidal behaviors. After delivery the most common cause of death in mothers is suicide, highlighting the severity of PPD.
The recent study published by Qiong Sha et al. in the Journal of Affective Disorders expands on previous research that looked at inflammation and kynurenine pathway dysregulation in women with PPD that experienced severe and suicidal depression. In the most recent study, the authors investigated associations between sex hormones, the kynurenine pathway and inflammation in the postpartum. Sha et al. reported that estrogen is positively correlated with the pro-inflammatory cytokine IL-6 and negatively correlated with serum kynurenine and picolinic acid levels. In their earlier study (Achtyes et al, 2019), depression was associated with increased IL-6 and IL-8 therefore suggesting that this hormone may contribute to PPD. However, they also found that progesterone was negatively correlated with the pro-inflammatory cytokine IL-1β, quinolinic acid, and nicotinamide. Their findings were consistent with previous studies that showed progesterone had anti-inflammatory effects. Importantly, this study also found that higher levels of estrogen and progesterone in the post-partum are linked to depression symptom severity.
Due to the dramatic changes in sex hormone levels in pregnant women, Dr. Qiong Sha hypothesizes that sex hormones may contribute to the gender disparity when it comes to depression. Dr. Sha thinks that investigating the effects of hormonal changes on mental health in other life stages such as during menopause is warranted. Currently, the Dr. Lena Brundin laboratory and collaborators are looking further into inflammation and kynurenine metabolite changes in individuals suffering from suicidal ideation with hopes of identify a potential biomarker that can be used to pinpoint depressed individuals who may be more at risk of suicide with the goal of providing optimal care.