The association between malnutrition and cognitive development in infancy as manifest in EEG functional connectivity and power spectral density

Malnutrition, particularly undernutrition, is a critical global health challenge, contributing to nearly half of all deaths among children under 5 and severely impacting physical and mental health, along with neural and cognitive development. Prior research by Xie et al. (2019a) linked growth faltering to altered EEG functional connectivity (FC) at 36 months and poorer cognitive outcomes at 48 months; however, no associations were found at 6 months for EEG measures or at 27 months for cognitive outcomes. Our study investigates these relationships in a sample of 12-month-old infants in Dhaka, Bangladesh, using various growth measurements (height/length-for-age, weight-for-age, weight-for-height/length, head-circumference-for-age, and mid-upper-arm-circumference-for-age z-scores) as indicators of nutritional status. Brain development was assessed through EEG, focusing on power spectral density (PSD) and FC, while cognitive development was evaluated with the Bayley Scales of Infant and Toddler Development, Fourth Edition. Our findings reveal that, at 12 months, growth faltering, indicative of undernutrition, was associated with reduced PSD, while initial correlations with increased FC did not remain significant after false discovery rate (FDR) correction. PSD was further positively linked to cognitive development, but associations with FC were not significant post-correction. Notably, EEG PSD in the theta and alpha bands mediated the relationship between malnutrition and behavioral outcomes. These results underscore the early impact of malnutrition on brain development, highlighting the importance of PSD in understanding neural development in this context. Our study emphasizes the need for early intervention and continuous monitoring to mitigate the adverse effects of malnutrition on infant brain and cognitive development.