Browsing by Author "Wolf, Pedro"

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    Associations between sleep architecture, cortisol concentrations, cognitive performance, and quality of life in patients with Addison's disease
    (2019) Henry, Michelle; Thomas, Kevin; Ross, Ian; Wolf, Pedro
    Recent literature in the neurosciences suggests that there are mechanistic relations between sleep disruption and cognitive (particularly memory) deficits, and that varying concentrations of the hormone cortisol may play a particularly important role in mediating those relations. Because patients with Addison’s disease (AD) experience consistent and predictable periods of sub- and supra-physiological cortisol concentrations (due to lifelong glucocorticoid replacement therapy), and because they frequently report disrupted sleep and poor memory, those presenting with that endocrinological disorder form an ideal population to use in studies testing hypotheses about the ways in which (a) disrupted sleep is related to impaired consolidation of previously learned material (and, hence, poor performance on tests assessing memory for that material), and (b) cortisol concentrations may mediate this relationship between sleep and memory. This dissertation presents four studies that, together, tested those hypotheses. Study 1 (n = 60 per group) found that patients with AD self-reported significantly more disturbed sleep and poorer cognition and quality of life compared to matched healthy controls. Importantly, our analyses suggested that disrupted sleep, and not AD per se, accounted most strongly for the reported cognitive impairment. Study 2 (n = 35 per group) found that patients had significantly poorer objectively-measured declarative memory performance compared to matched healthy controls, but that other domains of cognition were relatively unimpaired. Study 3 (n = 10 per group) suggested that matched healthy controls retained significantly more declarative information than patients. Importantly, while controls retained significantly more declarative information when a period of sleep, rather than waking, separated learning from recall, patients derived no such benefit. Study 4 (n = 7 per group) suggested that, relative to matched healthy controls, patients had different patterns of night-time cortisol secretion, accompanied by significantly reduced slow-wave sleep. Together, these four studies suggest that, despite being on replacement medication, patients with AD still experience disrupted sleep and memory deficits. These disruptions and deficits may be related to the failure of replacement regimens to restore a normal circadian rhythm of cortisol secretion. This pattern of results provides support for existing theoretical frameworks which posit that (in AD and other neuroendocrine, neurological, or psychiatric disorders) disrupted sleep is an important biological mechanism that underlies, at least partially, the memory impairments that patients frequently report experiencing. With specific regard to patients with AD, the findings presented here suggest that future initiatives aimed at improving patients’ cognitive performance (and, indeed, their overall quality of life) should prioritise optimizing sleep. More generally, this dissertation advances our understanding of sleep as a critical biological process essential for cognitive well-being.
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    Exploring factors that influence academic and behavioural outcome and the specific role of premorbid functioning, in a sample of children with severe traumatic brain injury
    (2014) Dollman, Aimee; Schrieff-Elson, Leigh; Figaji, Anthony; Wolf, Pedro
    Children who have sustained severe traumatic brain injury (TBI) demonstrate a range of deficits in neurocognitive and behavioural domains (Anderson, Northam, Hendy, &Wrennall, 2001; Babikian & Asarnow, 2009; van’t Hooft, 2010). These impairments may have adverse effects on academic and behavioural outcomes and can therefore interfere with school re-entry, educational progress, and ultimately, quality of life of the injured child (Anderson & Yeates, 2010; Keenan & Bratton, 2006; Lallo & van As, 2004). Pre-injury characteristics may increase risk for, and play a role in, TBI outcome, however, many studies exclude children with known adverse premorbid functioning (Dennis et al., 2007; Farmer etal., 2002). There are also dearth of published studies incorporating a variety of factors affecting outcome (e.g., socio economic status (SES), age at injury, time since injury, premorbid functioning, family environment) as well as academic and/or behavioural outcome variables in the same study generally. The broad aim of the study was therefore to contribute to the existing pediatric TBI (pTBI) literature on outcomes and factors influencing outcomes. In this study, I focused on investigating both academic and behavioural outcomes in a group of South African children of school-going age who had sustained a severe TBI. This study includes two parts. For the first part of the study, the aim was to explore the relationship between commonly reported factors that influence outcome after TBI (premorbid functioning, age at injury, time since injury, family environment and SES), and academic and behavioural outcome. For the second part of the study, the aim was to investigate the specific role of premorbid functioning in academic and behavioural outcome. The sample included 27 children who had been admitted to Red Cross War Memorial Children’s Hospital (RXH) and received intracranial monitoring for closed severe TBI between 2006-2011, who were of school-going age at the time of the injury. In terms of part one of the study, the results show elevated problems with academic outcome, and behavioural and executive functioning in the sample. The results also show that in this sample, factors such as family environment and premorbid functioning are particularly important with regards outcome in the home environment; while factors such as age at injury, family environment and SES play more of a role within the classroom environment.
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    An impact evaluation of a retail business skills training programme
    (2013) Chicheke, Aaron; Wolf, Pedro
    The South African retail industry is growing significantly and increasingly becoming an important contributor to the country's economic growth. The industry grew by 5.9 percent in 2011, in terms of sales, compared to 3.6 percent decline in 2009. According to figures provided by the Statistics South Africa (StatsSA), the industry contributed six percent to the entire South African economy and 23 percent towards total employment in the country. Despite the growing significance of the industry in the South African economy, the industry is still marred with chronic challenges of poor education and skills shortages. Major players in the industry indicated that these challenges are the main impediments to potential higher growth.
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    Poverty is behaviour: an evaluation of life history theory in Cape Town
    (2017) Smaill, Robin John; Wolf, Pedro
    This study used data from 2090 young adults and their households collected in a longitudinal survey in Cape Town from 2002 to 2009. The study examined factors influencing the educational achievement of the participants including environment, schools, parents and individual’s own behaviour. Multivariate regression was used to analyse the data. Results showed that the education system had the largest influence followed by adolescent behaviour and then parental behaviour. The environment had no significant effect. Both gender and wealth declined in importance when the behavioural variables were added to the model supporting the hypothesis that behaviour is associated with educational achievement and hence poverty. The findings of this research suggest that the Education Department appears to have non-educational objectives and family processes influences educational achievement. These circumstances need to be transformed if educational achievement and thereby poverty or inequality is to be addressed. Future surveys examining young adults should include more details of the environment, early childhood experiences, family processes and the parent/child relationship.
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    Program evaluation:principles, procedures and practises
    (Oxford University Press, 2007) Aurelio Jose Figueredo; Olderbak, Sally Gayle; Schlomer, Gabriel Lee; Garcia, Rafael Antonio; Wolf, Pedro
    This chapter provides a review of the current state of the principles, procedures, and practices within program evaluation. We address a few incisive and difficult questions about the current state of the field: (1) What are the kinds of program evaluations? (2)Why do program evaluation results often have so little impact on social policy? (3) Does program evaluation suffer from a counterproductive system of incentives? and (4) What do program evaluators actually do? We compare and contrast the merits and limitations, strengths and weaknesses, and relative progress of the two primary contemporary movements within program evaluation, Quantitative Methods and Qualitative Methods, and we propose an epistemological framework for integrating the two movements as complementary forms of investigation, each contributing to different stages in the scientific process. In the final section, we provide recommendations for systemic institutional reforms addressing identified structural problems within the real-world practice of program evaluation.