Associations between Sleep, Infant Feeding Methods, Brain Development and Behavior: A Multimodal Approach to Assess Plasticity in the Brain

Abstract

Sleep-disordered breathing (SDB) is a spectrum disorder that is estimated to effect a significant proportion of the pediatric population (1-3% in USA). SDB is able to disrupt and fragment sleep through frequent arousals and intermittent hypoxia. In addition, the long term effects of SDB in pediatrics have been well-documented; decreases in intelligence quotient (IQ), executive function, school performance, and alertness have all been observed. Although surgical treatments can be quite effective, there are no widely accepted prophylactic measures to prevent SDB development. Recently, breastfeeding duration in infancy has been demonstrated to be correlated with reduced SDB (lower AHI, RAI, and higher SpO2), as well as increases in IQ, executive function, and school performance (independent of SDB). The overarching goal of this dissertation was to examine the potential effects of both breastfeeding duration and SDB severity on the neurological underpinnings associated with observed behavioral and cognitive deficits; namely, correlations with white matter structural volume and fractional anisotropy (FA) scores through diffusion tensor imaging (DTI). Here, I proposed a unique developmental hypothesis where breastfeeding may ultimately reduce SDB, enabling the preservation of rapid eye movement (REM) sleep, and leading to healthier neurological white matter development. Method: Twenty-four children with SDB and 19 healthy controls were imaged using MR techniques. White matter volume was measured using the central 13 millimeters of the corpus callosum (CC). DTI of major white matter tracts was also conducted. The SDB group received neurocognitive testing to assess cognitive performance; the control group was assessed using real-world academic report cards. Finally, REM sleep was quantified in infants using overnight polysomnography (PSG), with SDB metrics and infant feeding method also measured. Results: There was no correlation between infant feeding methods and CC volume in either group, nor a significant differences between CC volumes in children with SDB versus those without. However, increased breastfeeding duration was correlated with increased left superior longitudinal fasciculus (LSLF) and left angular bundle (LAB) FA scores in healthy controls. In 8-9 month old infants, increased breastfeeding duration was also correlated with a reduced proportion of REM sleep (%TST), and children with exclusive breastfeeding had reduced SDB in infancy compared to children with any formula feeding. Finally, exclusively formula-fed infants were diagnosed with "primary snoring" more often than those with any amount of breastfeeding. Conclusions: The findings in this dissertation revealed associations between breastfeeding, SDB, REM sleep, and white matter integrity in the brain. These results support the hypothesis that certain cognitive effects associated with SDB and infant feeding methods may have common underlying anatomical brain changes that subserve these observed phenomena.