HighlightsWomen with antenatal depression have higher stress-related biomarkers than controls.Women with antenatal depression have shorter length of gestation than controls.Neonates exposed to antenatal depression have suboptimal neurobehavioural function.1-year-olds exposed to antenatal depression have increased cortisol stress-response.Maternal antenatal, and infant stress-related biomarkers are associated.

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Numerous studies have examined links between postnatal neurogenesis and depression using a range of experimental methods to deplete neurogenesis. The antimitotic drug temozolomide (TMZ) has previously been used successfully as an experimental tool in animals to deplete adult neurogenesis and is used regularly on human patients as a standard chemotherapy for brain cancer. In this study, we wanted to evaluate whether TMZ as a model for chemotherapy treatment could affect parameters related to depression in an animal model. Prevalence rates of depression in patients is thought to be highly underdiagnosed, with some studies reporting rates as high as 90%. Results from this study in mice, treated with a regimen of TMZ similar to humans, exhibited behavioural and biochemical changes that have relevance to the development of depression. In particular, behavioural results demonstrated robust deficits in processing novelty and a significant increase in the corticosterone response. Quantification of neurogenesis using a novel sectioning method, which clearly evaluates dorsal and ventral neurogenesis separately, showed a significant correlation between the level of ventral neurogenesis and the corticosterone response. Depression is a complex disorder with discoveries regarding its neurobiology and how it relates to behaviour being only in their infancy. The findings presented in this study demonstrate that chemotherapy-induced decreases in neurogenesis results in previously unreported behavioural and biochemical consequences. These results, we argue, are indicative of a biological mechanism, which may contribute to the development of depression in patients being treated with chemotherapy and is separate from the mental distress resulting from a cancer diagnosis.

Chronic stress can alter the immune system, adult hippocampal neurogenesis and induce anxiety- and depressive-like behaviour in rodents. However, previous studies have not discriminated between the effect(s) of different types of stress on these behavioural and biological outcomes. We investigated the effect(s) of repeated injection vs. permanent social isolation on behaviour, stress responsivity, immune system functioning and hippocampal neurogenesis, in young adult male mice, and found that the type of stress exposure does indeed matter. Exposure to 6 weeks of repeated injection resulted in an anxiety-like phenotype, decreased systemic inflammation (i.e., reduced plasma levels of TNFα and IL4), increased corticosterone reactivity, increased microglial activation and decreased neuronal differentiation in the dentate gyrus (DG). In contrast, exposure to 6 weeks of permanent social isolation resulted in a depressive-like phenotype, increased plasma levels of TNFα, decreased plasma levels of IL10 and VEGF, decreased corticosterone reactivity, decreased microglial cell density and increased cell density for radial glia, s100β-positive cells and mature neuroblasts—all in the DG. Interestingly, combining the two distinct stress paradigms did not have an additive effect on behavioural and biological outcomes, but resulted in yet a different phenotype, characterized by increased anxiety-like behaviour, decreased plasma levels of IL1β, IL4 and VEGF, and decreased hippocampal neuronal differentiation, without altered neuroinflammation or corticosterone reactivity. These findings demonstrate that different forms of chronic stress can differentially alter both behavioural and biological outcomes in young adult male mice, and that combining multiple stressors may not necessarily cause more severe pathological outcomes.

Background Little is known about the effects of depression before birth on the quality of the mother–infant interaction. Aims To understand whether depression, either in pregnancy or in lifetime before pregnancy, disrupts postnatal mother–infant interactions. Method We recruited 131 pregnant women (51 healthy, 52 with major depressive disorder (MDD) in pregnancy, 28 with a history of MDD but healthy pregnancy), at 25 weeks’ gestation. MDD was confirmed with the Structured Clinical Interview for DSM-IV Disorders. Neonatal behaviour was assessed at 6 days with the Neonatal Behavioural Assessment Scale, and mother–infant interaction was assessed at 8 weeks and 12 months with the Crittenden CARE-Index. Results At 8 weeks and 12 months, dyads in the depression and history-only groups displayed a reduced quality of interaction compared with healthy dyads. Specifically, at 8 weeks, 62% in the depression group and 56% in the history-only group scored in the lowest category of dyadic synchrony (suggesting therapeutic interventions are needed), compared with 37% in the healthy group (P = 0.041); 48% and 32%, respectively, scored the same at 12 months, compared with 14% in the healthy group (P = 0.003). At 6 days, neonates in the depression and history-only groups exhibited decreased social-interactive behaviour, which, together with maternal socioeconomic difficulties, was also predictive of interaction quality, whereas postnatal depression was not. Conclusions Both antenatal depression and a lifetime history of depression are associated with a decreased quality of mother–infant interaction, irrespective of postnatal depression. Clinicians should be aware of this, as pregnancy provides an opportunity for identification and intervention to support the developing relationship.