Million Women Study

The Million Women Study is the largest study of women's health in the world. In 1996-2001, a quarter of UK females then aged 50-64 years (1.3 million women) joined the study. Study participants have provided details about their lifestyle and health and given signed consent for follow-up. Since then their health has been followed mainly through electronic linkage to routinely collected NHS records. The aim of the study is to provide reliable information on potentially modifiable causes of common and serious illnesses, to help improve individual and public health. The study is jointly funded by Cancer Research UK, mostly for studies of cancer, and the Medical Research Council, mostly for studies of other conditions. We have described links between smoking, alcohol, obesity, and use of hormone replacement therapy and women's risk of developing various diseases, recently reporting that the harms of smoking and the benefits of stopping were greater in women than previously thought. This proposal is for research on dementia, osteoporosis, stroke and other severe disabling conditions that become increasingly common as women age. With this large study, detailed lifestyle information provided by women, and some 15 years follow-up through linkage to NHS medical records, we are uniquely placed to answer some major outstanding questions about what causes some of the serious conditions associated with ageing, and how they might be prevented. We have already been able to link the study cohort to NHS records on death, cancer incidence, and hospital admissions. In the next 5 years we will enhance the linkage with newly-available information on medications prescribed and on conditions diagnosed in general practice. Dementia is one of the most serious causes of disability as women age. There is surprisingly little good information about what people can do in middle-age to help prevent dementia occurring in later life. For example the effects of factors like smoking, alcohol, exercise and diet are still uncertain. Because dementia develops slowly over many years, and in the early stage can affect what people do, we need to study lifestyle factors over a long period before dementia is diagnosed. We will be able to follow large enough numbers of women for long enough to be able to provide reliable results, which other studies have not been able to do. With some 20,000 women in our study expected to develop dementia by 2017, we will also be able to study differences in risk factors for different types of dementia, such as Alzheimer's disease and vascular dementia. Osteoporosis, where bones become weak and liable to fracture, is increasingly common as women age. Osteoporotic fractures of the hip and other bones are major causes of pain, disability and death. Bisphosphonate drugs, such as alendronate, are commonly prescribed to prevent fractures and their use is increasing rapidly. In recent years controversy about the balance between the benefits and risks of long-term use of these drugs has been ignited by reports of potentially serious side effects, which we plan to investigate. We will also examine whether lifestyle factors in middle age, including diet and exercise, help prevent fractures occurring as women grow older. This research will be made possible by combining the health information women have so generously given us with the excellent medical records available for the UK population through the NHS.