Broadening the lens: How 25 years of prospective longitudinal studies have reshaped infant neurodevelopment in the majority world

Since the turn of the 21st century, advances in longitudinal research have underscored the critical importance of investing in early childhood development. Longitudinal neuroimaging, in particular, offers a powerful means of capturing within-person changes in infant brain development over time, rather than relying solely on age-based normative comparisons. Yet despite this progress, longitudinal infant neuroimaging studies, especially in Majority World contexts, remain the exception rather than the norm. As a result, opportunities to intervene during the first 1000 days, a crucial window for neurodevelopment, are often missed. Building on foundational work in Jamaica and Romania, recent studies in The Gambia, India, Brazil, South Africa and Bangladesh have begun to establish scalable, longitudinal metrics of neurodevelopmental change that can be implemented across diverse study sites. These approaches hold promise not only for integration into large, representative cohort studies, but potentially into standard healthcare practice, laying the groundwork for identifying infants who may benefit most from early intervention, particularly given that many neuroimaging biomarkers emerge before 12 months of age. There have also been promising advances in interventions targeting both psychosocial and biological sources of early adversity to improve neurodevelopmental outcomes for at-risk infants. Looking ahead, the full integration of neural markers into intervention studies across Majority World contexts will be essential to ensuring that all children, regardless of geography, have the opportunity to thrive.