2018 Research In Progress
Exploring the potential impact of physical activity on the association between smoking behaviour and cardiovascular disease risk in Alberta’s Tomorrow Project
Evidence from epidemiological studies indicates that there is increased risk of CVD events (including angina, heart attack and stroke) in smokers compared to non-smokers (Jenei et al 2000; Gikas et al 2016; Haddad et al 2016). By contrast, regular physical activity decreases the risk of chronic diseases including CVD events (Physical Activity Guidelines Committee (2008); U.S. Department of Health and Human Services (1996)).
The independent and opposing effects of tobacco smoking and physical activity on CVD risk are well documented but it is of interest to determine if physical activity mitigates the impact of smoking on CVD risk. In this study, we hypothesize that the increased risk of CVD events in smokers compared to non-smokers is lower at increasing amounts of physical activity compared to low physical activity levels. For example, greater physical activity levels could potentially reduce the increased risk of CVD events in smokers compared to non-smokers from 60% to only 30%.
The mitigating effect of physical activity on the impact of smoking in relation to CVD risk has previously been studied through a statistical interaction (Teramoto et al 2015; Linke et al 2009; Lee et al 2001). However, these studies have focused on leisure time physical activity, exercise capacity and energy expenditure respectively which do not capture all domains of physical activity. Moreover, most of these studies only used specific people in a population which limits generalizability.
In this study we propose a unique, multi-component comprehensive approach that has not been utilized before in a single study to further explore the interaction effect between physical activity and smoking status on CVD events risk among men and women participants in Alberta’s Tomorrow Project (ATP). Aside from including interaction in statistical analysis, the proposed research will consider all four domains of physical activity: occupation, transportation, household and leisure/recreational, as well as pack years of smoking (“pack years” defined as number of packs per day for a certain period of time).
N-3 long-chain polyunsaturated fatty acid status and breast cancer risk
Breast cancer is the most common type of cancer diagnosed in Canadian women – 1 in 9 Canadian women will be diagnosed in their lifetime. Despite ongoing advances in screening, prevention, diagnosis, and treatment; breast cancer remains the second-leading cause of cancer-related death. Animal studies and laboratory studies using human breast tumours suggest that the omega-3 polyunsaturated fatty acids, found mostly in fish, can reduce the risk of developing breast cancer. Measuring blood levels of the different omega-3 fatty acids is a more precise way to determine intake and status. We propose to look at participants from Alberta’s Tomorrow Project (ATP) as well as BC Generations Project (BCGP) who provided data and blood samples in order to look at dietary intake of omega-3 fatty acids as well as the levels of these fatty acids in blood. We will use dietary intake information from ~16,000 women in ATP as well as a blood sample donated by ~1000 women in ATP and BCGP (one third who have been diagnosed with breast cancer) to measure blood omega-3 fatty acid levels and also to determine if there is an association with breast cancer risk. To do this, we will account for other risk factors for breast cancer, such as family history and physical activity, to tease out the specific risk that might be associated with a low status of omega-3 fatty acids. This work will provide evidence as to whether omega-3 fatty acids reduce the risk of breast cancer, and will provide some reference levels for counselling women on how to reduce their risk.
Residential Relocation and Walking Study
There is growing interest in how the neighbourhood built environment (or “walkability”) shapes human behaviour, including physical activity. Studies have found positive associations between walkability and physical activity, and in particular recreational and transportation walking. Despite promising findings, most studies to date have estimated associations between walkability and walking from cross-sectional data. Cross-sectional data however, cannot provide causal evidence regarding the temporal direction of associations. Thus, based on current evidence it is difficult to determine if the estimated associations reflect higher walkability causing more physical activity or if the estimated associations just reflect the nonrandom process of already physically active adults seeking out neighbourhoods that have high levels of walkability (i.e., residential self-selection). Longitudinal residential relocation studies (a type of natural experiment) can provide causal evidence regarding the temporal direction of associations between the built environment and physical activity. We will use existing longitudinal data (n=10,330) collected from a random cross-section of Albertan adults (35-85 years) to investigate the extent to which changes in objectively-determined walkability are associated with changes in transportation and recreational walking following residential relocation. Evidence from this study will provide causal evidence that will be useful for urban form and transportation planners and policymakers in creating walkable neighbourhoods in Canada and elsewhere.
Exposure to ultraviolet radiation and the risk of hematologic malignancy and other site-specific cancer development
It is established that sun exposure causes melanoma and non-melanoma skin cancers. In contrast, there is evidence that moderate levels of sun exposure may reduce the risk of other cancers through the production of vitamin D. However, there is also evidence that continuously high levels of sun exposure may increase the risk of some cancers, specifically cancers of the blood. The proposed study aims to use data provided from over 245,000 participants combined in Alberta’s Tomorrow Project (ATP), Ontario Health Study (OHS), and CARTaGENE (Quebec cohort study) to measure the cancer risk associated with different levels of sun exposure.
Data from the ATP, OHS, and CARTaGENE were collected by questionnaires that include health and lifestyle behaviours, as well as sociodemographic characteristics. The primary objective of this study will be to combine questionnaire and cancer registry data to provide accurate risk estimates for different levels of sun exposure and specific types of cancer. Results from the study could provide clarity on the beneficial and detrimental amounts of sun exposure for site specific cancer development.
Developing socioeconomic indices for the study of lifestyle risk factors & cancer outcomes in Alberta’s Tomorrow Project
Reducing the prevalence of unhealthy lifestyle behaviours is an important challenge to address in order to reduce the burden of cancer in Canada. However, socioeconomically disadvantaged adults are much more likely to smoke, consume alcohol heavily, be physically inactive, have excess weight, and have poor dietary habits. Studying the influence of individual’s socioeconomic conditions or circumstances on the development of cancer is difficult because researchers need to capture many different aspects, such as one’s education, income, occupation, work status, and family structure.
We propose to construct two composite indices that will take into account these different socioeconomic aspects using available data from the Alberta’s Tomorrow Project, which follows since 2000 a large group of 31,072 adults aged 35-69 years with no previous history of cancer. Results of this study will generate new measurement tools to help researchers study more effectively the role of socioeconomic conditions and circumstances in the development of cancer. Results will also facilitate future research to generate important knowledge to help reduce the cancer burden among Canadians by tailoring existing recommendations and targeting specific socioeconomic groups.