Tesi di specializzazione (5 anni)
Nutrition and brain function: early nutritional supply and maturation of brain electrical activity in high preterm newborns
MEDICINA CLINICA E SPERIMENTALE
Corso di studi
relatore Dott. Guzzetta, Andrea
relatore Prof. Cioni, Giovanni
relatore Prof. Cioni, Giovanni
- brain maturation
- preterm birth
Data inizio appello
Data di rilascio
Background:<br>During the late second and third trimester of pregnancy, important processes of brain growth and maturation take place and the increasing survival rate of extremely and very preterm birth has brought attention on standard care practice that can influence long term outcome. <br>Early postnatal growth and nutrient intake have been demonstrated to influence brain growth and maturation with long term effects on neurodevelopment, but there is still concern in adopting fortified nutrition protocols. Postnatal growth restriction (EUGR) has been associated with delayed cortical maturation on MRI already at term age, even in the absence of clear brain damage (Vinall 2005),. EEG studies on unnourished preterms revealed that brain electrical activity can be dysmature since after birth and associated to a higher risk of developmental delay. However, very little is known on the specific early effects of nutrition on brain functional development. <br>Aim of my thesis has been to test the hypothesis that early nutritional supply can influence maturation of brain function as assessed by EEG. Automated EEG analysis provides reliable information on brain maturation, by quantifying the evolution of background activity in terms of discontinuity, synchronicity and spectral frequencies. <br>Method:<br>We analyzed routine EEG recorded at 32 (32,36 +/-0,69ds) and 36 (36,68 +/- 0,93ds) weeks PMA in a cohort of 30 preterms born ≤ 32 weeks (range 24,3-32) PMA and adopted automated quantization algorithms to measure maturational features of neonatal sleep EEG: 1) frequency spectra (absolute and relative values); 2) interemispheric and global synchrony using activation synchrony index (ASIintermispheric and ASIglobal); 3) length of interburst interval (IBI and MSC). We then correlated the composition of individual nutritional interventions during the first week of life with EEG parameters, growth curves and neurodevelopmental outcome at 12 months. <br>Results:<br>Lower daily caloric intake in the first week and lower lipid amounts correlated with a delayed maturation of EEG frequency spectra as expressed by the between-recordings reduction of the relative delta1 band power (0.5-1Hz) and increase of relative powers of higher frequencies (delta2, theta and alpha). This was also paralleled by a reduced modulation of the absolute total spectral power. Also, higher deficits of total protein intake (compared to the daily expected amount) significantly correlated with a lower increase in global synchrony and with higher level of dyscontinuity, suggesting that the maturation of those processes can be linked. Correlations were controlled for GA at birth and remained significant after excluding infants (n=7) with brain lesion. Finally, a lower protein intake in the first week significantly correlated with lower z-scores for head circumference. <br>Follow up revealed that babies with motor delay, as expressed by the lack of trunk control at 8 months of age, presented lower trends in growth curves compared to those without. No correlations were found between outcome measures and early nutrition nor with EEG maturational features.<br>Conclusions:<br>This is one of the first studies showing how early nutrition can affect the development of brain electrical activity in very preterm infants. Early nutritional supply seems to modulate brain functional maturation, not only related to caloric intake as a whole, but also with specific effects of diet composition in terms of macronutrients quantities. EEG automatic analysis revealed great potentiality in quantifying brain functional maturation over time. These observations reinforce interest in nutrition as an early intervention strategy, for its potentialities in influencing the neuroplastic processes of the maturing brain.
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