Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 130-145).

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / Nursing Studies / Master / Master of Nursing

Background Night shift work is inevitable for maintaining continuous services in different sectors e.g. healthcare, financial, transport and service sectors. Night shift work increases exposure of light at night. Exposure of light at night suppresses production of a neurohormone melatonin. Melatonin has shown potential cancer protective action in animal experiments. Melatonin deficiency is suggested to be related to the development of various cancer especially breast cancer. Breast cancer incidence in Hong Kong is rising. Particular concern about association between night shift work and breast cancer is raised. Objective To collect evidence from studies of other countries with study populations of different professions and to evaluate the relationship between night shift work and breast cancer Method MEDLINE was searched to identify publications, limited to English articles, from 1973 to May 2011. Search terms include (circadian rhythm or night work or night shift or shift work or work schedule tolerance) and (cancer or neoplasm or neoplasia) and (risk or rate or incidence). No restriction was set to the publication type. Results Altogether 343 titles retrieved from MEDLINE search. Finally, 8 primary observational studies that met inclusion criteria were identified for this review. Of these, two were prospective cohort studies, one was retrospective cohort study, two were nested case-control studies and three were case-control studies. Most of the study had crude exposure assessment of night shift work, in which four studies relied on group level of exposure probability instead of individual exposure information. Six of eight studies showed positive results on the association of night shift work and breast cancer in women. Three studies found that risk of breast cancer was increased significantly for those who had engaged in night shift work in a long duration i.e. more than 20-30 years, but they were all conducted in populations of same occupational group i.e. nurse and only a moderate increase of breast cancer risk was found. The results were subject to confounding and bias. No consistent results were found for effect of shorter duration of night shift work on risk of breast cancer. Conclusion Based on the studies included, there is suggestive evidence of an association of night shift work and breast cancer. Further studies on this are needed. Involvement of population of different occupational groups, controlling confounder of hormone use and conducting exposure assessment with high reliability using individual information instead of that from group are suggested. / published_or_final_version / Community Medicine / Master / Master of Public Health

Background: Prior studies regarding the risk factors of mild cognitive impairment (MCI), such as physical activity (PA) and sleep related factors in older Chinese populations are scarce, and the findings have not been consistent. Objectives: 1. To cross-sectionally and longitudinally examine the dose-response association between PA and cognitive function by Delayed Word Recall Test (DWRT) or Mini-mental State Examination (MMSE). 2. To cross-sectionally and prospectively examine the association of sleep related factors, including sleep duration, daytime napping, morning tiredness and insomnia, with cognitive function. Design: Cross-sectional and longitudinal analysis using both baseline and follow-up data from the GBCS. Methods Baseline data from 8,451 men and 22,067 women aged 50 years or above were used for the cross-sectional analysis. Among them, 4,214 men and 11,284 women participating in the second examination were included in the longitudinal analysis. Information on demographic, socioeconomic and lifestyle factors, and personal disease history was collected. Cognitive function was assessed by MMSE and DWRT under standardized protocols. Results 1. Significant dose-response relations across quintiles of metabolic equivalent value (METs) with DWRT score in participants with or without good self-rated health were found in cross-sectional analysis (all P for trend <0.001). 2. Prospectively, compared to those who were physically active, those with moderate activity or inactivity had increased risk for MCI. Regarding daily walking time, subjects with walking of 0.5 to 1 h, or ≥1 h had significantly reduced risk of MCI by 25% and 31% respectively compared with those who walked < 0.5 h per day. Subjects with low PA level at both baseline and follow-up had a significantly higher risk of MCI than those reporting PA at both baseline and follow-up. 3. Cross-sectionally, after adjustment for a range of potential confounders, an inverted U-shaped association between sleep duration and DWRT score was found, with 7 to 8 h of habitual sleep duration showing the highest score (P-values for trend from 3 to 7 h and from 7 to ≥10 h were all ≤0.001). Subjects with daily napping, morning tiredness, or insomnia had lower DWRT score than those without (P ranged from <0.001 to 0.01). 4. Prospectively, after adjustment for multiple risk factors, compared to sleep duration of 7 hours per day, those with sleep duration of 5 hours or less had increased risk for MCI by 43%. The adjusted P value for the linear trend from sleep duration of 3 hours to 7 hours per day was 0.01. The association remained after excluding those with poor health status. No significant associations of daytime napping, morning tiredness and insomnia with MCI were found. Conclusions In summary, we found a significant dose response association between PA and cognitive function in both cross-sectional and longitudinal analysis. One hour of daily walking is recommended for older Chinese people to delay or prevent cognitive decline. Short or long sleep duration may also be an important predictor of mild cognitive impairment. Sleep duration of less than 6 hours per day may indicate an increase risk of cognitive impairment in older people. / published_or_final_version / Community Medicine / Doctoral / Doctor of Philosophy

Background: Alzheimer’s disease, one type of dementia, is predicted to have great impact on society and economy. This effect increases rapidly especially in developing countries. The number of people with Alzheimer’s disease is huge due to the large population in China where the effects of this disease are amplified by the one-child policy. Objective: To review the risk factors of Alzheimer’s disease in different countries and offer some suggestions that how to prevent Alzheimer’s Disease in China that has very limited research on Alzheimer’s disease. To make recommendations for potential strategies to be implemented by policy-makers, government or other stakeholders. Method and results: Relevant studies which identified the risk factors for Alzheimer’s disease and evaluated the interventions and treatments for reducing the risk of getting Alzheimer’s disease, that were published between 1990 and 2012 were searched in PubMed and Google Academic using specific keywords. A total of 1071 studies were found and 62 used. Based on this systematic review, the risk factors of Alzheimer’s disease are age, lifestyle, family history and genetics, vascular, mild cognitive impairment, head injury as well as early-life negative events. There appear to be several important contributions to Alzheimer’s disease prevention including diet, cognitive activity, physical activity, social engagement, smoking cessation, and alcohol ingestion or simply being optimistic. Conclusion: This review has included the potential risk factors of Alzheimer's disease and the ways of preventing Alzheimer's disease, as well as to produce some possible strategies of preventing Alzheimer's disease based on the situation in China for the Chinese government and policy makers such as to use media as an important channel to draw people's attention about Alzheimer's disease and to educate about preventive factors. There should be government-funded education and health services in the rural areas and plans to build more leisure and sports centers in China. The government should also subsidize hospitals and medical centers to provide affordable or even free health examinations for people and build a central database for the purpose of recording, analysis and research into Alzheimer's disease for better understanding of the disease. Medical professionals and volunteers can help to enhance this database by the implementation of data collection to look for symptoms of Alzheimer’s disease. If the patients appear to have such symptoms, further data collection should be taking place, such as family history of Alzheimer’s disease, health status, head injuries, family status, characteristics and behavior, income levels, residential areas and other background information of the patients as part of their work whenever and wherever they go, especially in rural areas. / published_or_final_version / Public Health / Master / Master of Public Health

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M. Tech. Biomedical Sciences. / Aims to assess the prevalence rates of hyperlipidaemia, hyperglycaemia, elevated homocysteine levels, elevated FVII levels and high blood pressure, as risk parameters of arterial thrombosis, in a rural black community in the Limpopo Province South Africa.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences