Socioeconomic deprivation in early life and symptoms of depression and anxiety in young adulthood: mediating role of hippocampal connectivity

Abstract

Background: Experience of early-life socioeconomic deprivation (ELSD) may increase the risk of mental disorders in young adulthood. This association may be mediated by structural and functional alterations of the hippocampus.

Methods: We conducted a prospective cohort study on 122 participants of the European Longitudinal Study of Pregnancy and Childhood. Information about ELSD was collected via questionnaire from mothers during the first 18 months of participants' lives. At age 23-24, participants underwent examination by structural magnetic resonance imaging, resting-state functional connectivity and assessment of depressive symptoms (Mood and Feelings Questionnaire) and anxiety (Spielberger State-Trait Anxiety Inventory). The association of ELSD with brain outcomes in young adulthood was assessed with correlations, linear regression (adjusting for sex, socioeconomic position and mother's mental health) and moderated mediation analysis.

Results: Higher ELSD was associated with greater depressive symptoms (B = 0.22; p = 0.001), trait anxiety (B = 0.07; p = 0.02) and lower global connectivity of the right hippocampus (B = -0.01; p = 0.02). These associations persisted when adjusted for covariates. In women, lower global connectivity of the right hippocampus was associated with stronger trait anxiety (B = -4.14; p = 0.01). Global connectivity of the right hippocampus as well as connectivity between the right hippocampus and the left middle temporal gyrus mediated the association between ELSD and trait anxiety in women. Higher ELSD correlated with a lower volume of the right hippocampus in men, but the volume of the right hippocampus was not related to mental health.

Conclusions: Early preventive strategies targeted at children from socioeconomically deprived families may yield long-lasting benefits for the mental health of the population.

Keywords: anxiety; depression; fMRI; sex differences.

Fig. 1.

Global connectivity of the right hippocampus and its relation to early-life socioeconomic deprivation. The left side on the figure shows axial brain slices displaying the average global functional connectivity map of the right hippocampus. The right side of the figure shows an association of higher early-life socioeconomic deprivation (x-axis) and lower global connectivity of the right hippocampus in young adulthood (y-axis). Coordinates (voxels): 75; 109; 80. The cluster of voxels characterizing global connectivity of the right hippocampus included right and left frontal pole, brain stem, precuneus, lateral occipital cortex, right and left temporal pole, right and left superior frontal gyrus, left middle frontal gyrus, lateral occipital cortex, right middle frontal gyrus, right and left lingual gyrus and other regions (see online Supplementary Table S4). Model 1 shows the association of higher early-life socioeconomic deprivation (x-axis) with lower global connectivity of the right hippocampus in young adulthood (y-axis), adjusted for sex and covariates related to early-life socioeconomic position (mother's education, father's education, father's occupation, household income, basic utilities, household items and crowding ratio). Model 2 shows the association of higher early-life socioeconomic deprivation (x-axis) with lower global connectivity of the right hippocampus in young adulthood (y-axis), adjusted for sex and covariates related to mother's mental health (mother's depression and mother's anxiety).

Fig. 2.

Moderated mediation analysis. Results are B (standard error); *p < 0.05. (a) Global connectivity of the right hippocampus as a mediator between early-life socioeconomic deprivation and mental health in young adulthood, conditional on sex. (b) Connectivity between the right hippocampus and the left middle temporal gyrus as a mediator between early-life socioeconomic deprivation and mental health in young adulthood, conditional on sex.