Peer-reviewed article

Early-life stature, preschool cognitive development, schooling attainment, and cognitive functioning in adulthood: a prospective study in four birth cohorts

Aryeh D. Stein, Linda S. Adair, Georgina Donati, Charlotte Wray, Linda Richter et al. · 13 Dec 2022

Summary

Written by AI, not yet AICS's view · claude-haiku-4-5-20251001

This study tracked 2,614 children from birth cohorts in Brazil, Guatemala, the Philippines, and South Africa to understand how early childhood height, child IQ, and schooling affect adult cognitive ability. Early-life height was weakly associated with adult IQ when considered alone, but this relationship largely disappeared when accounting for child IQ and years of schooling completed. Child IQ emerged as a stronger and more consistent predictor of adult cognitive outcomes across all four countries. The findings suggest that while nutrition and growth matter for health, improving cognitive outcomes in adulthood may require interventions that specifically target early cognitive development rather than growth alone.

Key points

Early-life stature showed weak associations with adult IQ (ranging from -0.14 to 3.17 IQ points per height-for-age Z-score) that were largely explained by child IQ and schooling
Child IQ was a consistent and stronger predictor of adult IQ across all groups (3.91 to 10.02 IQ points per standard deviation)
When child IQ was controlled for, the association between early stature and adult IQ was substantially reduced or eliminated
Higher child IQ was associated with more years of schooling (0.25 to 1.30 years per SD) across all cohorts
The interaction between schooling and child IQ, but not between schooling and early stature, predicted adult IQ

Limitations

The study is observational and cannot establish causation; findings varied across the four cohorts and by sex, limiting generalisability. The mechanisms linking early growth, cognitive development, and schooling require further investigation.

Abstract

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.

Findings the Hub has extracted

Each claim below is labelled by its type of design and links back to this report.

SurvivalDevelopment

BRGTPHZA

Problem

Understanding whether early childhood growth faltering impairs long-term cognitive development and adult intelligence

Intervention: No intervention tested; this is an observational study examining natural variation in early-life stature, child IQ, and schooling and their association with adult cognitive outcomes
Population: 2,614 individuals from four birth cohorts: Brazil (born 1993), Guatemala (born 1969-77), Philippines (born 1983-84), and South Africa (born 1990)