Melbourne School of Psychological Sciences - Theses
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ItemLongitudinal outcome of a preterm birth: evaluation of an intervention program and an exploration of effects of maternal environment on preschool children born preterm( 2013)While survival rates of preterm infants continue to improve, a significant number of surviving preterm infants display ongoing cognitive and behavioural problems. Environmental factors, including stress from medical and routine procedures in the Neonatal Intensive Care Unit (NICU) and problematic parent-infant interactions are now thought to influence developmental outcomes for preterm infants. The mother forms a large part of the infant’s environment and in the first 3 years of life environmental factors that may influence preterm infants include her relationship with the infant and also her capacity to organise, structure and regulate the infant’s interaction with other external experiences. In a landmark study (Nurcombe et al., 1984) found significant benefits emerging after 2 years on cognitive development (IQ )following early intervention in the NICU – the Mother Infant Transaction Program (MITP). The MITP is a relatively inexpensive parent-based program aimed at improving the neurodevelopmental outcomes for preterm infants. Study 1 was a follow-up at 36 months of 90 preterm infants, of less than 30 weeks gestation, who received either the intervention (a modified version of the MITP), or a control condition in a RCT. An ANOVA design was used with treatment entered as the fixed variable, and hospital and gender were entered as random variables. The results showed that there were no overall treatment effects on cognitive variables, executive function variables, or behavioural variables. However, the results were complex to interpret. In this field of study, where sample sizes are limited, consideration of the effect sizes is important, nonetheless the effect sizes in this study were unremarkable. While it may be that the results accurately reflect that at 36 months, the Premiestart modified MITP had no effect on the variables measured. Other possible explanations were that the preterm infants needed more time to recover and show the benefits of the intervention program, as shown in other studies where benefits emerged at later ages. Further it may have been that perhaps the measures were not sensitive enough to detect any differences between the groups, and finally it may be that improved standards of care in the NICU have reduced the impact of the intervention. It was also shown that the infants born at a later gestation, and who were less sick (as measured by length of hospital stay) had better cognitive achievement scores compared with the infants born earlier and who spent longer in hospital. Thus the MITP intervention may be effective only with very preterm infants, and not extremely preterm infants. Further follow-up research was recommended. Study 2 was one of the few reported studies exploring the relationship between maternal variables including: sensory profile, personality, maternal executive function and maternal emotion regulation on the neurobehavioural outcomes of preterm infants at 36 months, using a correlation-based design. Results showed that maternal executive functioning was highly correlated with preterm child executive functioning and behaviour. Maternal emotion regulation was also highly correlated with preterm child executive functioning and behaviour. A maternal sensory style of Low registration was predictive of preterm child behavioural outcomes. There were isolated correlations between maternal variables and preterm child cognitive outcomes. These findings were discussed in terms the theoretical framework of intersubjectivity, which is widely applied to understand infant mental health and development within the context of the relationship with the primary caregiver, and is consistent with the notion that the environment of the preterm infant/child is largely influenced by maternal behavioural characteristics. When planning interventions to assist preterm infants, consideration of maternal factors is warranted. It is possible that interventions could be more specifically targeted to address unique maternal characteristics.
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ItemMood and anxiety outcomes in adolescents born with extremely low birthweight or extremely preterm: prevalence and neuroanatomy( 2012)Preterm birth is associated with poor outcome in a range of domains, which can persist into adolescence and beyond. This may include poor mental health outcomes, and particularly, anxiety and depressive symptoms. To date, studies of mood and anxiety outcomes in preterm groups have mainly used dimensional measures of symptoms; only a handful employ clinical diagnostic instruments and these largely focus on recent symptoms. Our understanding of the prevalence of clinically diagnosable disorders is consequently limited, particularly in late adolescence and for those born since 1990. Prematurity at birth can also have a significant and longstanding impact on brain development. An extended medial network, including the hippocampus, amygdala, and medial prefrontal cortex, is implicated in emotion regulation, as well as clinical mood and anxiety disorders. Hippocampus, amygdala, and prefrontal structure may be altered in preterm samples, but potential relationships between these brain regions and emotional outcomes are yet to be explored in preterm survivors. This study aimed to address these limitations in the current literature by i) characterising mood and anxiety outcomes in adolescents born extremely low birthweight or extremely preterm (ELBW/EP), ii) characterising the structure of regions in the extended medial network, and iii) investigating the relationships between these outcomes and brain structure. A number of specific hypotheses arose from this research question. Firstly, it was expected that the ELBW/EP group would report more recent symptoms, more frequently meet diagnostic criteria for current or past disorder, and more strongly endorse personality traits associated with anxiety and depression than a normal birthweight (>2500g; NBW), full-term (>36 weeks; FT) control group. Secondly, it was expected that ELBW/EP participants may have smaller hippocampus, amygdala, and ventromedial prefrontal cortex volumes, and thinner ventromedial prefrontal cortices, than NBW participants. Finally, it was predicted that structural reductions in these regions of interest would be associated with greater mood and anxiety symptoms, and a history of clinically diagnosable disorder, in ELBW/EP and NBW participants. This study assessed 215 ELBW/EP and 157 NBW adolescents who were born in 1991 and 1992 in the state of Victoria, Australia. Participants from a prospective geographical cohort were followed up at age 18 and completed measures of mood and anxiety symptoms and disorders (including questionnaires and a structured clinical interview), as well as personality traits. Participants also underwent structural MRI scanning, and cortical and subcortical brain volumes were generated using FreeSurfer (v5.0). Unexpectedly, there was no elevation in clinically relevant recent or lifetime history of depression or anxiety in the ELBW/EP group. Although mood and anxiety disorders were more prevalent in females overall, there was no interaction between group and gender. The ELBW/EP group had disproportionately smaller bilateral hippocampus volumes and left amygdala volumes than controls, and the ventromedial prefrontal cortex was proportionately larger and thicker in the ELBW/EP group than the NBW group. Recent mood and anxiety symptoms were not well predicted by any of the neuroanatomical variables of interest. Despite this, lifetime history of a mood or anxiety disorder was associated with smaller left vmPFC volumes. Further analyses indicated this pattern was apparent in those with a history of anxiety disorder but not mood disorder. Group did not moderate these findings. Assessment of ELBW/EP adolescents’ self-reported mood and anxiety outcomes revealed an encouraging picture. Although extremely low birthweight or extreme prematurity was associated with altered structure of regions in the extended medial network, these alterations appeared to have limited relationship with outcomes. These findings contribute to the literature by examining older adolescent mood and anxiety outcomes and using high field-strength neuroimaging. The implications for preterm survivors and the relevance of brain structure to mood and anxiety outcomes in this age group are considered.
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ItemAdult psychiatric outcomes of very low birth weight survivors: exploring mechanisms of risk and vulnerability( 2010)This study sought to determine the rate and nature of mental health problems in adults born very low birth weight (VLBW) and to explore whether developmental risk factors contribute to the development of these problems. Childhood studies have identified relationships between birth weight and a variety of behavioural and psychiatric outcomes, including attention deficit hyperactivity disorder (ADHD), mood and anxiety disorders and other negative psychological outcomes. However, the evidence is less clear as to whether these problems persist into adulthood. Previous research has also explored the biological basis for system impairment in VLBW individuals, hypothesised to affect stress-response systems (such as hypothalamic-pituitary-adrenocortex-axis functioning), and whether social/environment risk ‘triggers’ are required before biological alteration associated with VLBW is observed. However, few studies have prospectively followed VLBW survivors from birth, through childhood and adolescence and into adulthood, and even fewer have attempted to explore the nature and effects of possible biological system impairment in this population, in terms of whether biological, social and environmental adversity increases VLBW risk of psychopathology in adulthood. The current study addressed the limitations of previous research by using a prospective, longitudinal study design. A cohort of 117 VLBW and 32 NBW participants were followed from birth, at age two, five, eight, fourteen and eighteen years, and most recently, aged between mid to late twenties. Screening measures were combined with semi-structured clinical interviews for full diagnostic adult psychiatric assessment. The findings suggested that VLBW adults were more likely to be diagnosed with a psychiatric disorder than NBW peers. VLBW participants born less than1000 g also tended to have higher scores on measures of psychopathology compared with VLBW participants born 1000–1500 g. Further, adult adverse life event stress was found to be related to psychiatric outcomes for VLBW participants. In conclusion, VLBW adults were at greater risk of psychopathology than NBW peers, with those VLBW adults with lower birth weights and high adult adverse life event stress most vulnerable to experiencing psychiatric disorder.