The effect of cumulative early life adversities, and their differential mediation through hair cortisol levels, on childhood growth and cognition: Three-year follow-up of a birth cohort in rural India

Background: Early adversities negatively impact children’s growth and development, putatively mediated by chronic physiological stress resulting from these adverse experiences. We aimed to estimate the associations between prospectively measured cumulative early with cognition outcomes in rural Indian preschool children explore if hair cortisol concentration (HCC), a measure of stress, above association. Methods: Participants were recruited SPRING cRCT Haryana, India. Adversities experienced through pregnancy first year life 1304 at 12-months. HCC was 12-months 845 them. Outcome measures height-for-age-z-score (HAZ), weight-for-age-z-score (WAZ) cognition, 1124 followed up 3-years. Cognition using validated tablet-based gamified tool named DEEP. Results: Cumulative inversely associated all Each unit increase adversity score led decrease 0·08 units [95% confidence interval (CI):-0·11,-0·06] DEEP-z-score; 0·12 [-0·14,-0·09] HAZ 0·11 [-0·13,-0·09] WAZ. 12-month DEEP-z-score (-0·09 [-0·16,-0·01]) (-0·12 [-0·20,-0·04]), but association WAZ not significant (p = 0·142). marginally (proportion 0·06, p 0·014). No evidence mediation found for outcome. Conclusions: have persistent negative effects on child The two differentially HCC, no observed cognitive outcome. Future studies should focus other biomarkers, alternate pathways such as immune, inflammation cellular ageing pathways, unpack key mechanisms underlying established relationship poor outcomes.