Ruth V Grunau
Relevant Degree Programs
Affiliations to Research Centres, Institutes & Clusters
Graduate Student Supervision
Doctoral Student Supervision
Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.
As part of their lifesaving care in the neonatal intensive care unit (NICU), infants born very preterm (between 24 and 32 weeks gestation), undergo frequent invasive procedures that induce pain and stress, during a period of rapid brain development. We examined whether repeated exposure to invasive procedures was associated with altered brain development, and thereby poorer neurodevelopmental and behavioral outcome in children born very preterm. We also explored whether parent interaction moderates long-term effects of invasive procedures on child behavior. Data were collected from two prospective cohorts of infants born ≤32 weeks gestation between February 2001–July 2004 and March 2006–January 2009. Neonatal data were recorded from birth to term-equivalent age. Infants in the 2006–2009 cohort were scanned sequentially, once near birth and again at term-equivalent age. Infants in the 2001–2004 cohort were followed-up at 18 months corrected age (CA), and again at 7.5 years of age, when they underwent an MRI. At 18 months CA, parents of the 2001–2004 cohort completed questionnaires and participated in a recorded play session with their child, from which the parent-child interaction was later coded. All statistical analyses were adjusted for known neonatal and clinical confounders. In a series of 4 studies, greater exposure to invasive procedures in the NICU was associated with slower postnatal body and head growth, and slower growth was associated with delayed cerebral cortical maturation. Among the preterm children exposed to a higher number of invasive procedures, more positive parental interaction was associated with fewer anxious/depressive behaviors reported at 18 months CA. Furthermore, greater exposure to invasive procedures was related to poorer white matter maturation at 7.5 years, and together these factors predicted lower IQ. Greater exposure to invasive procedures was associated with slower body and head growth, altered brain maturation and poorer outcomes, after adjustment for clinical confounders. It is necessary that pain management strategies be evaluated for the extent that they are brain protective, in order to minimize the long-term impact of ongoing pain/stress in the NICU. Furthermore, interventions should address the parent-child relationship in order to improve later outcomes.
Infant attention is central to early development. Previous research has linked focused attentionduring infant exploratory play to preschool cognition. Importantly, focused attention andinformation processing have been related to sustained decreases in heart rate (HR), which showdevelopmental changes in infancy. Few studies have examined the relationship between focusedattention, heart rate and development in very preterm infants, who are vulnerable to cognitive andattention problems. Participants were 35 extremely low gestational age (ELGA; ≤28 weeks), 48very low gestational age (VLGA; 29-32 weeks) and 46 healthy term-born infants seen at 8-months corrected age. Focused attention was timed and global focused attention was rated using atoy exploration paradigm. Heart rate was recorded continuously during attention testing. MeanHR and heart rate variability (HRV) were assessed during infant exploration. Additionally,change in mean HR for all focused episodes, and the mean and greatest HR change for the peakfocus were calculated. Bayley Scales of Infant Development (BSID-II, Mental DevelopmentIndex [MDI]) were administered.Term-born infants were rated higher on global focused attention than VLGA, andmarginally higher than ELGA infants. For all infants, greater HRV suppression duringexploration and magnitude ofHR deceleration during the peak focus were related to greaterattentiveness. No group differences were seen in HRV suppression. However, ELGA infantsshowed greater HR deceleration during focused attention compared to VLGA and Term-borninfants. Furthermore, after controlling for perinatal risk, infant peak focus and degree of HRdeceleration predicted 8-month MDI for the ELGA (49% of the total variance), but not VLGAinfants. This may reflect enhanced attentional effort to compensate for information processingdeficits among the highest risk infants. These findings extend research on attention and heart rateduring exploratory play to understanding the links between attention regulation, heart rate andcognitive development in very preterm infants. Further knowledge in this area will facilitate thedevelopment of effective methods to identify infants very early in life who are at-risk for attentionand cognitive problems, and may lead to interventions that can improve developmental outcomesfor vulnerable infants.
Master's Student Supervision
Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.
Children born very preterm are exposed to repeated neonatal procedures that induce pain and stress during hospitalization in the neonatal intensive care unit (NICU). The COMT Val158Met genotype is involved with pain sensitivity, and early life stress is implicated in altered expression of methylation of the serotonin transporter. We examined: (1) whether methylation of the serotonin transporter gene (SLC6A4) promoter differs between very preterm children and full-term controls at school age, (2) relationships with child behavior problems, and (3) whether the extent of neonatal pain exposure interacts with the COMT Val158Met genotype to predict SLC6A4 methylation at 7 years in the very preterm children. We examined the associations between the COMT genotypes, neonatal pain exposure (adjusted for neonatal clinical confounders), SLC6A4 methylation and behavior problems. Very preterm children had significantly higher methylation at 7/10 CpG sites in the SLC6A4 promoter compared to full-term controls at 7 years. Neonatal pain (adjusted for clinical confounders) was significantly associated with total child behaviour problems on the Child Behavior Checklist (CBCL) questionnaire (adjusted for concurrent stressors and 5HTTLPR genotype, p = 0.035). CBCL Total Problems was significantly associated with greater SLC6A4 methylation in very preterm children (p = 0.01). Neonatal pain (adjusted for clinical confounders) and COMT Met/Met genotype were associated with SLC6A4 promoter methylation in very preterm children (p = 0.001). These findings provide evidence that both genetic predisposition and early environment need to be considered in understanding susceptibility for developing behavioral problems in this vulnerable population.