Aryeh D Stein, Linda S Adair, Georgina Donati, Charlotte Wray, Linda M Richter, Shane A Norris, Alan Stein, Reynaldo Martorell, Manuel Ramirez-Zea, Ana M B Menezes, Joseph Murray, Cesar Victora, Nanette Lee, Isabelita Bas, Alysse Kowalski, Ann DiGirolamo, Gaia Scerif, Feziwe Mpondo, Delia Belleza, Lukhanyo Nyati, Clive Osmond, Judith Rafaelita Borja, Delia Carba, Tita Lorna Perez, Sonny Agustin Bechavda, Maria F Kroker-Lobos, Jithin S Varghese, Fernando C Barros, Fernando P Hartwig, Bernardo L Horta, Fernando C Wehrmeister
Background: Nutrition is important for growth and brain development and therefore cognitive ability. Growth faltering in early childhood, an important indicator of early adversity, is associated with poorer developmental outcomes, some into adulthood, but this association probably reflects early-life deprivation. We aimed to investigate the associations between early-life stature, child IQ, and adult IQ. Methods: In this cohort study, we used prospective longitudinal data collected in four birth cohorts from Brazil (born in 1993), Guatemala (born in 1969–77), the Philippines (born in 1983–84), and South Africa (born in 1990). Using multivariable linear models, we estimated the relative contributions of early-life stature, child IQ, and schooling (highest school year completed) to adult IQ, including interaction effects among the early-childhood measures and schooling. Findings: We included 2614 individuals in the analysis. Early-life stature was associated with adult IQ (range across eight site-by-sex groups –0·14 to 3·17 IQ points) and schooling (–0·05 to 0·77 years) per height-for-age Z-score. These associations were attenuated when controlling for child IQ (–0·86 to 1·72 for adult IQ and –0·5 to 0·60 for schooling). The association of early-life stature with adult IQ was further attenuated when controlling for schooling (–1·86 to 1·21). Child IQ was associated with adult IQ (range 3·91 to 10·02 points) and schooling (0·25 to 1·30 years) per SD of child IQ in all groups; these associations were unattenuated by the addition of early-life stature to the models. The interaction between schooling and child IQ, but not that between schooling and early-life stature, was positively associated with adult IQ across groups. Interpretation: The observed associations of early-life stature with adult IQ and schooling varied across cohorts and sexes and explained little variance in adult IQ beyond that explained by child IQ. These findings suggest that interventions targeted at growth for health and early development are important. Our results are consistent with the inference that improving long-term cognitive outcomes might require interventions that more specifically target early cognitive ability. Funding: Bill & Melinda Gates Foundation. © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.
Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States; Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; Department of Psychiatry, University of Oxford, Oxford, United Kingdom; DSI-NRF Centre of Excellence in Human Development, University of the Witwatersrand, Johannesburg, South Africa; SAMRC Developmental Pathways for Health Research Unit, University of the Witwatersrand, Johannesburg, South Africa; MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Global Health Research Institute, School of Human Development and Health & NIHR Southampton Biomedical Research Centre, University of Southampton, Southampton, United Kingdom; INCAP Research Center for Prevention of Chronic Diseases, Institute of Nutrition of Central America and Panama, Guatemala City, Guatemala; Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil; Human Development and Violence Research Centre, Federal University of Pelotas, Pelotas, Brazil; USC-Office of Population Studies Foundation, University of San Carlos, Talamban, Cebu, Cebu City, Philippines
