Early human capital, the COVID-19 food-insecurity shock, and adult mental health: a 22-year cohort study in Ethiopia, India, and Peru

Mental disorders typically emerge before age 25, yet little is known about how childhood human capital and large economic shocks jointly shape mental health into adulthood in low- and middle-income countries (LMICs). We use seven rounds of the Young Lives study (2002-2024), which followed two birth cohorts in Ethiopia, India, Peru, and Vietnam, to examine (i) the long reach of early human capital, proxied by the height-for-age z-score in infancy; (ii) the medium-term association between household food insecurity during the COVID-19 pandemic and adult depressive (PHQ-8) and anxiety (GAD-7) symptoms measured at ages 22 and 29 in 2023-2024; and (iii) whether early human capital buffered the pandemic shock. We estimate value-added, latent-factor, dynamic panel, and mediation models with cluster-robust inference. Early height-for-age strongly predicts adult height (1.6 cm per standard deviation, p < 0.01) but not adult mental health or formal employment. Pandemic food insecurity predicts higher depressive (0.41 points, 0.12 standard deviations) and anxiety (0.41 points, 0.11 standard deviations) symptoms three to four years later (both p < 0.01); per step, the probability of clinically relevant anxiety (GAD-7 of 10 or more; base 7.6 percent) rises by 1.9 percentage points (p = 0.001) and of clinically relevant depression (PHQ-8 of 10 or more; base 5.6 percent) by 1.0 percentage point (p = 0.07). The gradient travels with the persistence of distress and of material hardship, is robust to attrition corrections and bounds, and its causal reading is explicitly bounded, since mental health was first measured during the pandemic itself. Exploratory analyses suggest the gradient differs across countries and may be larger in the older cohort, exposed at about age 26 rather than 19; these contrasts rest on few clusters and are not robust to multiple-comparison adjustment. Early human capital neither predicts adult mental health--a precise null of at most {+/-}0.03 standard deviations--nor moderates the gradient. Protecting household food security during aggregate shocks, especially for young adults, appears central to safeguarding mental health in LMICs.