IL6 and major depressive disorder: In order to investigate how different forms of psychosocial adversity impact those two biological systems, our current study aimed to test the associations of proximal (e.g., family functioning, caregiver’s depression, and anxiety) and distal (e.g., socioeconomic disadvantage) early-life adversities with salivary inflammatory biomarkers (IL-6, IL-8, TNF-α, and IL-1β cytokines) and a panel of hair HPA axis markers (cortisol, cortisone, and DHEA) in young children between 3 months and 5 years of age.