Physiological Consequences of Undernutrition on Neurodevelopment in the First 1000 Days of Life: A Longitudinal Cohort Study in Rural Zamfara State

The first 1000 days from conception to age two constitute a critical neurodevelopmental window during which undernutrition exerts enduring physiological effects on brain structure, connectivity, and function. No longitudinal study has examined these consequences systematically in rural North West Nigeria, where stunting rates among the highest in the world. This study investigated the physiological consequences of early undernutrition on neurodevelopment in a birth cohort from rural Zamfara State, North West Nigeria. A prospective longitudinal cohort enrolled 180 mother-infant dyads at birth, with follow-up assessments at 6, 12, and 24 months. Nutritional status was characterised by anthropometry, haemoglobin, zinc, and iodine status. Neurodevelopmental outcomes were measured by the Bayley Scales of Infant and Toddler Development and electroencephalographic spectral power as a neurophysiological marker of cortical maturation. Hair cortisol was collected as a stress exposure marker. Caregiver stimulation quality was assessed using the Home Observation for Measurement of the Environment scale. Growth curve modelling, latent variable analysis, and structural equation modelling were applied. Results showed that stunting at 12 months predicted significantly lower Bayley cognitive and language scores at 24 months. Iodine deficiency was independently associated with reduced frontal theta EEG power, a marker of delayed cortical maturation. Iron deficiency anaemia compounded cognitive delays beyond stunting alone. Hair cortisol elevation mediated 18 percent of the stunting-cognition relationship. This study provides pioneering longitudinal neurophysiological evidence from rural northern Nigeria. Integrated nutrition and stimulation intervention packages are recommended. Keywords: undernutrition, neurodevelopment, first 1000 days, stunting, Zamfara State.