Background

In addition to individual risk factors and behaviors, health is also affected by a range of socio-economic (SES) conditions often measured as income or level of education. More evidence is needed to advance our understanding of how adverse SES conditions are internalized as psychosocial stressors that are manifested as perturbations in biological systems such as patterns of gene expression within the blood circulation.

Methods

Adverse social conditions were measured as a composite score, social disadvantage, generated from perceived neighborhood environment, level of education, per-capita family income and wealth. Random Forests was used to investigate the relationship between social disadvantage and gene expression, in the whole blood RNA-seq profiles of 180 African Americans and the mediatory role of stress and depression scales in that relationship.

Results

A set of 191 mRNA could classify social disadvantage with and area under the curve (AUC) of 0.98. Subsets of those 191 mRNA were related to depression scale, perceived stress scale and financial stress scale. The relationships between social disadvantage and the three psychosocial factors were also established though the questionnaire data. A total of 44 of the 191 mRNAs were reported as differentially expressed between depressive subjects and controls in a study of clinical depression (major depressive disorder, MDD).

Conclusions

The mRNAs identified are involved in mainly 3 areas related to the brain: brain development/neuroplasticity, neurobehavioral response to chronic stress and neurobehavioral and neurodegenerative diseases.The results suggest that subjects above the threshold of depressive symptoms, measured in the data, are likely exhibit a gene expression signature that corresponds to an increased risk of a clinical diagnosis of depression.