The causes of eating disorders are complex, yet a number of factors have emerged that may put individuals at increased risk for developing these disorders. These include social factors, such as social exclusion and personality traits, such as perfectionism. With support from a 2003 MSFHR Trainee Award, Brandy McGee studied how perfectionism combines with cultural influences, such as physical ideals suggested in advertisements, to cause eating disorders. Brandy is now exploring how multidimensional perfectionism interacts with experiences of social exclusion to produce eating disturbances. She is testing the hypothesis that social rejection will lead to an upswing in eating disturbances (such as binge eating, thoughts about food, negative mood, etc.) in individuals with high levels of social dimensions of perfectionism, but not in women with low levels of perfectionism. The outcomes of this study will help us better understand how social factors shape health status and enable us to better predict who is at risk for eating problems, and to intervene earlier to promote health.
Research Pillar: Population Health
Aboriginal youth suicide and cultural continuity
Aboriginal youth in Canada have the highest suicide rate of any culturally distinct population in the world. In B.C., Aboriginal youth take their own lives twice as often as Aboriginal adults, and at a rate estimated at five to 20 times that of the non-native population. However, what these statistics fail to show is that rates of youth suicide vary dramatically across B.C.’s almost 200 Aboriginal bands. Ninety per cent of Aboriginal youth suicides occur in less than 10 per cent of the bands, and youth suicide is virtually unknown in a quarter of bands. Some Aboriginal communities are committed to their cultural past and invested in a shared future. For example, some Aboriginal bands have cultural facilities and a measure of communal control over health, education, policing and child welfare services. This cultural continuity has an impact on lowering suicide rates. Travis Proulx is investigating whether community efforts to teach Aboriginal youth their native language also predict future wellbeing. If young people who are competent in their native language are less likely to commit suicide or be involved in serious accidents, band councils and governments can use this information to design programs that build Aboriginal youth resilience and help prevent suicide.
Molecular epidemiology of Giardia lamblia in British Columbia’s drinking water supplies
Giardia lamblia is a waterborne parasite that causes giardiasis, a diarrheal disease commonly called ""beaver fever”. Despite the comprehensive water quality management measures in B.C., this parasite is often detected in surface water supplies and is the second leading cause of gastrointestinal illness in the province. While current surveillance methods for G.lamblia in water supplies allows for enumeration of the parasite in water, the test cannot differentiate between infectious and non-infectious strains. Natalie Prystajecky is examining a library of archived water samples collected across B.C. over 13 years to determine if the strains in B.C. surface water are infectious to humans and how frequently, what the sources are, and where these strains are found. She is also assessing the effectiveness of control measures such as watershed protection and agricultural waste management best practices in protecting water quality. This information could lead to more effective environmental and health policies and public health interventions.
Cluster Analysis for High-Dimensionality Population Health Data
Population health research seeks to develop a better understanding of how social, cultural, environmental, occupational and economic factors determine health status. While most population health research focuses on specific hypotheses, understanding the bigger picture can yield insights on a larger scale. How socio-economic factors influence or correlate with health status, how diseases group together in constellations, and how these relate to health services usage, medication usage and health-driven outcomes are all important questions. Cluster analysis (CA) is a class of statistical techniques that can be applied to data that exhibit natural patterns. However, current CA methods are poorly suited to broad population health data, which may contain hundreds of variables with many dimensions. The result is that patterns between classes of variables can be lost in the statistical “noise.” Eric Sayre is developing a new method of CA called Cluster Analysis for High-Dimensionality Data (CAHDD), which provides a means for filtering statistical noise, and allowing important patterns to emerge from the data. By applying CAHDD to Canadian population health data, Eric’s research seeks to answer big-picture questions about socio-economic factors and health status. CAHDD will be available for other health researchers to interpret population health data, leading to significant advances in our understanding of the determinants of health status in our population.
Improved Biostatistical Methods to Detect Gene-by-Environment Interaction in Case Control Association Studies
Complex genetic diseases are thought to result from genetic susceptibility factors acting in conjunction with environmental, lifestyle or non-genetic factors such as infectious, chemical, physical, nutritional and behavioural exposures. In the past, researchers have used the case-control study design to investigate disease associations with non-genetic factors. Recently, new genetic information in the form of Single Nucleotide Polymorphisms (SNPs) has been integrated into these population health studies in an attempt to better understand the joint effects of non-genetic and genetic risk factors. However, conventional statistical methods for this study design are not powerful enough to detect such joint effects, even for studies with very large sample sizes. Jihyung Shin is developing new biostatistical methods to more efficiently extract information from case-control data about statistical interactions between genetic and non-genetic risk factors for disease. By developing extensions of the methodology to allow for missing information on genetic risk factors in a statistically valid way, her work can accommodate the analysis of disease associations with SNP haplotypes, which are combinations of genetic variants at several nearby SNPs on the same chromosome. This type of analysis can offer improved power over analysis of single SNPs for detecting the effects of genetic factors and their interactions with non-genetic risk factors. The ability to identify interactions between genes and non-genetic factors that affect the risks of complex genetic disorders will improve our understanding of disease pathogenesis and help with the development of more effective and appropriate treatments, prevention and screening tools.
An examination of injection drug use sites: the influence of social and physical context on drug-related harms and public health interventions
Injection drug use may result in severe health consequences including increased risk of viral infections such as HIV and hepatitis C, soft tissue infections, and drug overdose. Recently, with increasing attention being paid to the impact of environment on individual and public health, intervention efforts for injection drug users (IDUs) have moved beyond the modification of individual behaviour and focused on modifying the environments in which people use injection drugs. One recent and controversial example of this involves medically supervised injection facilities, where IDUs can inject pre-obtained illicit drugs under the supervision of health care professionals. William Small is studying and comparing three types of injecting settings in the Downtown Eastside: private injecting spaces (such as homes), public injecting spaces (such as alleys), and Vancouver’s supervised injecting facility. He is examining how the social and physical context of each setting influences the ability of injection drug users to employ HIV-prevention measures and safer injection practices. The findings of this research will build important knowledge about the health and HIV vulnerabilities of IDUs in the Downtown Eastside. Also, this research will provide information on the impact of current interventions, which may inform future interventions for addressing injection drug use.
Exposure to polybrominated diphenyl ether (PBDE) flame retardants and thyroid effects in pregnant women
Polybrominated diphenyl ethers (PBDEs) are chemical flame retardants used in furniture foams, certain textiles and many plastics. In Vancouver, PBDE levels in human breast milk increased by about 15 fold from 1992 to 2002, bringing current levels to among the highest reported in the world. While the human health effects from ambient PBDE exposure are unknown, animal and laboratory studies indicate that PBDEs alter the levels and transport of thyroid hormones. This is of particular concern during pregnancy, when thyroid hormones play a critical role in fetal brain development. Because even small changes in maternal thyroid hormone levels in early pregnancy have been linked to neurological deficits in children, the thyroid disrupting potential of PBDEs is of interest for public health. Glenys Webster’s study is examining the relationships between PBDEs and thyroid hormones in 150 pregnant women in Vancouver. Using blood tests, her work will determine whether PDBEs are associated with altered thyroid hormone levels at different stages of pregnancy. A detailed questionnaire will also be used to identify the main sources of maternal exposure to PBDEs. Ultimately, Glenys’ research may lay the foundation for future investigations of PBDEs, other environmental toxins and neurological development in children in Vancouver.
Coping with Rheumatoid Arthritis: The Effect of Psychosocial Factors on Chronic Pain
Rheumatoid arthritis (RA) is an incurable disease that affects approximately 1 per cent of the western population. It is associated with a variety of symptoms including chronic pain, stiffness and inflammation of joints, fatigue, and frequent mood changes. Because there is no cure, treatment focuses on alleviating symptoms and maintaining mobility and function. Disease factors only partially predict pain and disability among RA patients; consequently, there is growing interest in the influence of psychological and social factors on the progression of this disease. Amy Zwicker is examining the role and degree to which social support from friends and family, and effective coping strategies may help to decrease pain and increase functional ability in people living with RA. She is also examining the effects of these psychosocial factors on mood and physical well-being of patients and their spouses. Findings from her research may contribute to the development psychologically-based interventions that help RA patients deal more effectively with the pain and disability associated with the disease.
The exploration of genetic conditions affecting the health of aboriginal people
Canadian aboriginal people have shorter life spans and an increased burden of disease compared to their non-native Canadian counterparts. As in all populations, complex disease—both genetically and environmentally determined—plays a significant role. For example, among the Inuit of Baffin Island, the prevalence of one type of congenital heart defect is four times as high as in other populations.
Dr. Laura Arbour is exploring the genetic and environmental determinants of heart defects among the Inuit of Baffin Island. She will determine the contributing factors of genetics, intake of nutrients that are important in heart development (such as folate and vitamin A) and environmental exposures during pregnancy. She will also assess whether current public health efforts to reduce birth defects by fortifying flour with folic acid are sufficient for people in a northern environment. The goal of her research is to inform public health efforts aimed at prevention, early recognition of symptoms and timely treatment.
Psychosocial determinants of adolescent health behaviour
There are numerous segments of the Canadian population who experience a disproportionate burden of ill health. A key issue in addressing this disparity is the early identification of those groups of people who are vulnerable to poor health outcomes over the course of their lifespan. Identification of these groups, and the factors leading to this vulnerability, is a priority for researchers. One area of interest is in identifying the early childhood determinants of health behaviours, such as a child’s health, stress in the family, economic conditions or neighbourhood safety. Dr. Stefania Maggi studies the extent to which early influences can predict which children will follow trajectories of health vulnerability throughout the lifespan. Her research uses a combination of administrative databases, national surveys, and longitudinal data collection to follow up on the same individuals over a number of years, spanning developmental phases from early childhood to adolescence and young adulthood. By identifying what factors in childhood increase the likelihood of unhealthy behaviours and/or poor educational outcomes during adolescence her research will inform early prevention efforts aimed at the social determinants of health.