Development Pathways for Health Research Unit
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DPHRU addresses the national priorities of increasing life expectancy, decreasing maternal and child mortality and strengthening health system effectiveness. It investigates genetic, physiological, psycho-social, and lifestyle determinants of growth and development, obesity and risk of cardio-metabolic diseases, and healthy ageing. DPHRU adopts a multidisciplinary approach and associated methodologies to understand physical and mental health across the life course and the transgenerational effects and to identify possible interventions schemes to improve health outcomes. The Unit also forms a unique research platform with substantial infrastructure and equipment, extensive longitudinal data and well-established links with the urban and rural South African communities. Using more than twenty years of longitudinal data from the Birth-to-Twenty cohort study and longitudinal statistical modelling, the growth and development from birth to 20 years of age of children born in 1990 in Soweto has been characterised. The analysis of BT20 data together with data from other cohort studies in low and middle income countries contributed to the findings that show that low birth weight and greater weight gain in childhood (after 2 years) increases adiposity, as well as diabetes and hypertension risk in later life. Linear growth, but not weight gain, in the first two years of life is positively associated with school attainment. |
It was found that while black girls have a similar physical growth and pubertal development as their white peers, black boys have a delayed growth and development (By approximately 6 months) in comparison to their white counterparts. These results suggest that some biological triggers of growth and pubertal development are different between boys and girls. It was also found that children who had more adiposity (measured by body mass index) and/or were taller at 5 or 8 years of age were more likely to have an early onset of puberty, a risk factor for cardio-metabolic diseases and an important determinant for reproductive behaviour and health. For instance, 50% of the girls in the cohort had their sexual debut at 16 years old, about 3.5 years after the mean age at menarche calculated for the cohort. Besides the fact that these results are unique in sub-Saharan Africa, the longitudinal description of growth and pubertal maturity is also important for the investigation of their determinants and effects on physical and mental health across the life-course. Another important biological aspect of ageing and health that has been the focus of recent work at DPHRU has been on the menopausal transition where it was shown that the menopausal transition in black South African women has been associated with a decrease in lean mass and bone mineral density. |
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These results and others provided the motivation for DPHRU to start the Soweto First Thousand Days project (S1000), a new longitudinal pregnancy and infant cohort study, which aims to do an in-depth Investigation on the maternal biological and psycho- social factors that influence foetal and infant growth and development. Most of the research recently published by DPHRU researchers has focused on the childhood and adolescent factors that lay down the premise of cardiovascular and metabolic risks in young adulthood. Based on the BT20 cohort, it has been shown that the prevalence of overweight and obesity increases progressively between childhood and adolescence, particularly in females. Children are at a significantly higher risk of becoming obese by late adolescence (16–18 years) if they were overweight or obese between ages 4 and 8 years. Data from the 10 year longitudinal follow-up study showed that the prevalence of obesity rose by 14%. With regard to cardio-vascular risks, 22% of the BT20 children had high blood pressure (BP) at 5 years of age and a third of those had sustained the elevated BP status at 18 years of age. This raises the importance of routine blood pressure assessment in paediatrics for early identification of at-risk children, which may inform timely interventions to prevent elevated blood pressure in later life. In the ageing population, the role of behavioural factors in determining the risk of obesity and cardio-metabolic risks has been investigated longitudinally in the mothers of the BT20 study participants. Results show that while vigorous intensity activity is associated with significantly smaller gains in body weight and fat mass over time, only 45% of black South African women participated in leisure time physical activity.
Finally, Professor Kuzawa opened discussions around a new hypothesis on the evolution and origins of diabetes. He and his colleagues postulated that the diabetes-causing condition of insulin resistance, wherein muscle tissue’s uptake of glucose is lowered, could be a strategy to prioritise the use of glucose for the brain over other tissues during the childhood peak in brain glucose needs. Inaugural Lecture : Professor Shane Norris The research findings highlighted the importance of maternal and child nutrition in the first 1000 days, which includes pregnancy and first two years of infancy, for programming growth and body composition of children but that childhood and adolescence were stages of opportunity to optimise health. |
DPHRU has recently launched the African Centre for Obesity Prevention (ACTION) which aims to raise awareness on obesity and associated diseases by providing evidence-based information on obesity, and to engage with the public through recommendations on how to engage in a healthy lifestyle. Building the costly human brain: Implications DPHRU and the DST-NRF Centre of Excellence in Human Development presented a lecture by Professor Christopher Kuzawa, Anthropologist, University of North-western, US, in the frame of their series of public seminars on the Evolutionary Biology of Human Development and Health. In his talk entitled Building the costly human brain: implications for the evolution of childhood and the origins of diabetes, Professor Kuzawa presented his and his colleague’s recent results around the implication of the energy costs of human brain on growth and metabolism. Using brain imaging data, they showed that brain energy demands peaks at 4-5 years of age when neuronal connections expands with learning and cognitive development. In addition, they found that the rate of body weight growth is slowest at ages when the brain is most costly and is fastest when the brain is least costly. It suggests that human’s unique characteristic of slow and prolonged linear growth during childhood could be an evolutionary strategy to conserve resources and to feed the “unusually high costs of our brain development”.  Photograph: John M Pettifor, Honorary Research Professor andProfessor Emeritus, Developmental Pathways for Health Research Unit,Wits Department of Paediatrics; Professor Tawana Kupe, Deputy ViceChancellor: Advancement, HR and Transformation; Professor Shane Norris; Professor Martin Veller, Dean, Wits Faculty of Health Sciences
Professor Norris started at Wits in 1998 as a research officer and now has over 17 years research experience in longitudinal cohort studies and life-course epidemiology. His research expertise includes maternal and child health, child nutrition, growth and body composition and intergenerational transmission and developmental origins of obesity and metabolic disease risk. His greatest scientific impact has been his research that showed that varying early life growth patterns confer different risk trajectories for Type 2 diabetes in adult life. |
Unit Director: Professor Shane Norris