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Epidemiology is the study and analysis of the distribution, patterns and determinants of health and disease conditions in a defined population.
Cerebrovascular disease includes a variety of medical conditions that affect the blood vessels of the brain and the cerebral circulation. Arteries supplying oxygen and nutrients to the brain are often damaged or deformed in these disorders. The most common presentation of cerebrovascular disease is an ischemic stroke or mini-stroke and sometimes a hemorrhagic stroke. Hypertension is the most important contributing risk factor for stroke and cerebrovascular diseases as it can change the structure of blood vessels and result in atherosclerosis. Atherosclerosis narrows blood vessels in the brain, resulting in decreased cerebral perfusion. Other risk factors that contribute to stroke include smoking and diabetes. Narrowed cerebral arteries can lead to ischemic stroke, but continually elevated blood pressure can also cause tearing of vessels, leading to a hemorrhagic stroke.
Cerebral edema is excess accumulation of fluid (edema) in the intracellular or extracellular spaces of the brain. This typically causes impaired nerve function, increased pressure within the skull, and can eventually lead to direct compression of brain tissue and blood vessels. Symptoms vary based on the location and extent of edema and generally include headaches, nausea, vomiting, seizures, drowsiness, visual disturbances, dizziness, and in severe cases, death.
Stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke:
The Framingham Heart Study is a long-term, ongoing cardiovascular cohort study of residents of the city of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects from Framingham, and is now on its third generation of participants. Prior to the study almost nothing was known about the epidemiology of hypertensive or arteriosclerotic cardiovascular disease. Much of the now-common knowledge concerning heart disease, such as the effects of diet, exercise, and common medications such as aspirin, is based on this longitudinal study. It is a project of the National Heart, Lung, and Blood Institute, in collaboration with Boston University. Various health professionals from the hospitals and universities of Greater Boston staff the project.
Sir Richard Peto is an English statistician and epidemiologist who is Professor of Medical Statistics and Epidemiology at the University of Oxford, England.
Intracerebral hemorrhage (ICH), also known as hemorrhagic stroke, is a sudden bleeding into the tissues of the brain, into its ventricles, or into both. An ICH is a type of bleeding within the skull and one kind of stroke. Symptoms can vary dramatically depending on the severity, acuity, and location (anatomically) but can include headache, one-sided weakness, numbness, tingling, or paralysis, speech problems, vision or hearing problems, memory loss, attention problems, coordination problems, balance problems, dizziness or lightheadedness or vertigo, nausea/vomiting, seizures, decreased level of consciousness or total loss of consciousness, neck stiffness, and fever.
Hepatitis B is endemic in China. Of the 350 million individuals worldwide infected with the hepatitis B virus (HBV), one-third reside in China. As of 2006 China has immunized 11.1 million children in its poorest provinces as part of several programs initiated by the Chinese government and as part of the Global Alliance for Vaccines and Immunization (GAVI). However, the effects of these programs have yet to reach levels of immunization that would limit the spread of hepatitis B effectively.
Sir Rory Edwards Collins FMedSci FRS is a British physician who is Professor of Medicine and Epidemiology at the Clinical Trial Service Unit within the University of Oxford, the head of the Nuffield Department of Population Health and a Fellow of Green Templeton College, Oxford. His work has been in the establishment of large-scale epidemiological studies of the causes, prevention and treatment of heart attacks, other vascular disease, and cancer, while also being closely involved in developing approaches to the combination of results from related studies ("meta-analyses"). Since September 2005, he has been the Principal Investigator and Chief Executive of the UK Biobank, a prospective study of 500,000 British people aged 40–69 at recruitment.
Chronic, non-communicable diseases account for an estimated 80% of total deaths and 70% of disability-adjusted life years (DALYs) lost in China. Cardiovascular diseases, chronic respiratory disease, and cancer are the leading causes of both death and of the burden of disease, and exposure to risk factors is high: more than 300 million men smoke cigarettes and 160 million adults are hypertensive, most of whom are not being treated. An obesity epidemic is imminent, with more than 20% of children aged 7–17 years in big cities now overweight or obese. Rates of death from chronic disease in middle-aged people are higher in China than in some high-income countries.
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction to the heart muscle. The most common symptom is retrosternal chest pain or discomfort that classically radiates to the left shoulder, arm, or jaw. The pain may occasionally feel like heartburn.
The epidemiology of cancer is the study of the factors affecting cancer, as a way to infer possible trends and causes. The study of cancer epidemiology uses epidemiological methods to find the cause of cancer and to identify and develop improved treatments.
Nutritional epidemiology examines dietary and nutritional factors in relation to disease occurrence at a population level. Nutritional epidemiology is a relatively new field of medical research that studies the relationship between nutrition and health. It is a young discipline in epidemiology that is continuing to grow in relevance to present-day health concerns. Diet and physical activity are difficult to measure accurately, which may partly explain why nutrition has received less attention than other risk factors for disease in epidemiology. Nutritional epidemiology uses knowledge from nutritional science to aid in the understanding of human nutrition and the explanation of basic underlying mechanisms. Nutritional science information is also used in the development of nutritional epidemiological studies and interventions including clinical, case-control and cohort studies. Nutritional epidemiological methods have been developed to study the relationship between diet and disease. Findings from these studies impact public health as they guide the development of dietary recommendations including those tailored specifically for the prevention of certain diseases, conditions and cancers. It is argued by western researchers that nutritional epidemiology should be a core component in the training of all health and social service professions because of its increasing relevance and past successes in improving the health of the public worldwide. However, it is also argued that nutritional epidemiological studies yield unreliable findings as they rely on the role of diet in health and disease, which is known as an exposure that is susceptible to considerable measurement error.
A silent stroke is a stroke that does not have any outward symptoms associated with stroke, and the patient is typically unaware they have suffered a stroke. Despite not causing identifiable symptoms, a silent stroke still causes damage to the brain and places the patient at increased risk for both transient ischemic attack and major stroke in the future. In a broad study in 1998, more than 11 million people were estimated to have experienced a stroke in the United States. Approximately 770,000 of these strokes were symptomatic and 11 million were first-ever silent MRI infarcts or hemorrhages. Silent strokes typically cause lesions which are detected via the use of neuroimaging such as MRI. The risk of silent stroke increases with age but may also affect younger adults. Women appear to be at increased risk for silent stroke, with hypertension and current cigarette smoking being amongst the predisposing factors.
Remote ischemic conditioning (RIC) is an experimental medical procedure that aims to reduce the severity of ischaemic injury to an organ such as the heart or the brain, most commonly in the situation of a heart attack or a stroke, or during procedures such as heart surgery when the heart may temporary suffer ischaemia during the operation, by triggering the body's natural protection against tissue injury. Although noted to have some benefits in experimental models in animals, this is still an experimental procedure in humans and initial evidence from small studies have not been replicated in larger clinical trials. Successive clinical trials have failed to identify evidence supporting a protective role in humans.
Colin Baigent is a British academic physician and cardiovascular epidemiologist. He is a professor of epidemiology, Director of the Medical Research Council Population Health Research Unit at the University of Oxford, and deputy director of the Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), part of Oxford Population Health. His work is focused in the design and coordination of large-scale randomised trials and the use of meta-analysis to assess the efficacy and safety of drugs for the prevention of cardiovascular disease (CVD) or premature death.
The West of Scotland Coronary Prevention Study was a landmark randomized controlled trial, published in 1995, that investigated the effects of pravastatin, a cholesterol-lowering drug, on primary prevention of coronary heart disease (CHD) in men with hypercholesterolemia. Conducted in the early 1990s, this study provided critical evidence on the benefits of statins in reducing cardiovascular events in individuals without a history of CHD. It concluded that statin treatment reduced CHD events by 31% after nearly five years of treatment.
India has an estimated 100 million people formally diagnosed with diabetes, which makes it the second most affected in the world, after China. Furthermore, 700,000 Indians died of diabetes, hyperglycemia, kidney disease or other complications of diabetes in 2020. One in six people (17%) in the world with diabetes is from India. The number is projected to grow by 2045 to become 134 million per the International Diabetes Federation.
A cerebroprotectant is a drug that is intended to protect the brain after the onset of acute ischemic stroke. As stroke is the second largest cause of death worldwide and a leading cause of adult disability, over 150 drugs have been tested in clinical trials to provide cerebroprotection.
References
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