Study Results Link Postpartum Depression to Inflammation

The results of a recent study published in Brain, Behavior, and Immunity suggest that inflammation and the kynurenine pathway may be connected to postpartum depression (PPD) and therefore may present new treatment targets in severe PPD.¹

Although PPD is common, with the US Department of Health and Human Services estimating that 1 in 9 new mothers has the condition,² the researchers said that severe depression with suicidality during pregnancy and postpartum is an understated disorder.¹

Previous studies have suggested that the condition may be triggered by dynamic changes of the immune system during and after pregnancy. The cross-sectional study aimed to establish whether a pro-inflammatory status in plasma, combined with changes in the kynurenine pathway activity, is associated with the development of severe PPD and suicidal behavior.¹

The kynurenine pathway is the primary route for tryptophan catabolism in the liver. Dysregulation or overactivation of the pathway has been associated with immune system activation and accumulation of potentially neurotoxic compounds.³

The researchers analyzed plasma IL-1β, IL-2, IL-6, IL-8, TNF-α, tryptophan, serotonin, kynurenine, nicotinamide, and quinolinic- and kynurenic acids in postpartum women diagnosed with peripartum-onset depression.¹

They found that increased plasma IL-6 and IL-8, when combined with reductions of IL-2, quinolinic acid, and serotonin was associated with the severity of depressive symptoms and increased the risk for PPD.¹ Furthermore, women with lower serotonin levels had an increased risk for suicidal behavior, even when adjusting for age, body mass index, depression severity, medication, and psychosocial factors.¹

These findings suggest that severe PPD is linked with dysregulation of the immune response and the kynurenine pathway, with a concomitant reduction in serotonin levels. The researchers concluded that this finding may present the possibility of novel therapeutic strategies targeting women during pregnancy.¹

REFERENCES

• Achtyes E, Keaton S, Smart L, et al. Inflammation and kynurenine pathway dysregulation in post-partum women with severe and suicidal depression. Brain Behav Immun. 2020;83:239-247. doi: 10.1016/j.bbi.2019.10.017.
• US Department of Health and Human Services. Postpartum depression. Office on Women’s Health website. womenshealth.gov/mental-health/mental-health-conditions/postpartum-depression. Updated May 14, 2019. Accessed Dec 2, 2019.
• Davis I, Liu A. What is the tryptophan kynurenine pathway and why is it important to neurotherapy? Expert Rev Neurother. 2015;15(7):719-721.