Socioeconomic Status Is Associated With Reward Processing, Interleukin 1β, Striatal Connectivity, and Antidepressant...

Major depressive disorder (MDD) is a common condition with heterogeneous risk factors. Socioeconomic status (SES) is one such risk factor, which is negatively linked to MDD treatment outcomes and symptom severity. SES is associated with altered resting-state functional connectivity (RSFC) in reward-processing circuitry and elevated proinflammatory cytokine levels in individuals without depression. However, how the negative consequences of low SES exacerbate MDD psychopathology is poorly understood.

Data on SES (household income and education), depression severity, self-reported reward processing, serum proinflammatory cytokine levels, and neuroimaging for 323 adult participants (211 patients with MDD receiving open-label escitalopram, 112 control participants without depression; 63.4% female) were obtained from the CAN-BIND-1 (Canadian Biomarker Integration in Depression Study-1) dataset. General linear models assessed the effects of MDD diagnosis and SES on self-reported reward processing and proinflammatory cytokine levels. Whole-brain seed-to-voxel RSFC analyses were performed for the dorsal and ventral striatum leveraging 249 participants (150 patients with MDD, 99 control participants; 62.2% female). We also assessed the impact of SES on response to open-label escitalopram.

Participants with MDD from households with lower incomes displayed lower goal pursuit behaviors, decreased interleukin 1β levels, and slower improvement to escitalopram relative to those from households with higher incomes. Using a lenient z > 2.3 threshold, MDD household income correlated with striatal RSFC with the dorsolateral prefrontal and posterior cingulate cortices.

Our results elucidate the role of SES and its negative consequences in altering reward processing and antidepressant treatment efficacy in MDD, corroborating previous literature suggesting that SES significantly impacts health outcomes. Better characterizing the relationship between SES and MDD psychopathology may inform future treatment approaches and intervention development.