The Framingham Heart Study:
The Town That Changed America's Heart
For 50 years, the Framingham Heart Study and the residents of Framingham, Massachusetts, have been synonymous with the remarkable advances made in the prevention of heart disease in the United States and throughout the world.
Fifty years of data collected from residents of Framingham have produced over 1,000 scientific papers, identified major risk factors associated with heart disease, stroke and other diseases, paved the way for researchers to undertake singular clinical trials based on Framingham findings, created a revolution in preventive medicine, and forever changed the way the medical community and general public view the genesis of disease.
The study is one of the most important epidemiological studies in the annals of American medicine. While its contributions in the area of heart research are legion, researchers also are utilizing new data to investigate stroke, dementia, osteoporosis, arthritis, diabetes, eye disease, cancer and the genetic patterns of many common diseases.
Two generations of study participants and dedicated researchers from the National Heart , Lung, and Blood Institute (NHLBI), Boston University, other area universities and collaborators around the world have revolutionized the way we view, treat and prevent cardiovascular disease and a host of other disorders. Investigators hope to add a third generation of participants in the near future.
Before Framingham, most physicians believed that atherosclerosis was an inevitable part of the aging process and were taught that blood pressure was supposed to increase with age enabling the heart to pump blood through an elderly person's narrowed arteries.
Before Framingham, the notion that scientists could identify and individuals could modify "risk factors" ( a term coined by the study) tied to heart disease, stroke and other diseases was not part of standard medical practice.
The majority of physicians did not understand the relationship, for example, between high levels of serum cholesterol and heart attacks. Many did not believe that modifying certain behaviors could enable their patients to avoid or reverse the underlying causes of serious heart and vascular conditions.
With a mounting epidemic of cardiovascular disease beginning in the 1930s, the United States Public Health Service decided to undertake a large- scale study to investigate why heart disease had become the nation's number one killer by the late 1940s.
Researchers wanted to learn which biologic and environmental factors were contributing to such a rapid rise of cardiovascular death and disability. They settled on an epidemiological approach -- a novel idea at the time -- designed to learn how and why those who developed heart disease differed from those who escaped it.
Fifty years ago, the town of Framingham was selected by the U.S. Public Health Service as the study site, and 5,209 healthy residents between 30 and 60 years of age, both men and women, were enrolled as the first cohort of participants. It was the first major cardiovascular study to recruit women participants.
In its first year, the study responsibilities were assumed by the National Heart Institute, now the National Heart, Lung, and Blood Institute. Through a contract with the NHLBI, researchers from the Boston University School of Medicine (BUSM) have played an important role in the Framingham Heart Study. Both NHLBI and BUSM scientists have added to our knowledge about reducing disability and death from heart disease.
In 1971, the study recruited 5,124 children (and their spouses) of the original cohort for a second study, the "Offspring Study." With two generations worth of data, the Framingham Heart Study acquired an unmatched base of scientific riches.
More recently, 500 members of Framingham's minority community have been recruited to participate in the Omni Study. The Omni Study is continuing its recruitment. It was initiated to determine whether the risk factors associated with disease for these individuals are the same or different than what researchers have seen in the other two cohorts.
Every two to four years, study participants are given extensive medical examinations including a medical history, blood tests and other sophisticated tests such as bone scans, eye exams and echocardiograms assessing multiple aspects of their current health status.
From the Study: Major Risk Factors for Cardiovascular Disease Identified
Today, managing cholesterol levels, high blood pressure and diabetes to mitigate heart and vascular disease and stroke is fundamental to good medical care. In fact, it's hard to remember a time when these and other risk factors were not considered to be significant problems by many physicians.
But, before Framingham, the role of serum cholesterol in the evolution of cardiovascular disease was not widely understood or accepted by physicians as a major contributing factor. The study established a relationship between the levels of cholesterol and risk for disease. Further, the study established a strong positive association of LDL cholesterol with coronary heart disease as well as a powerful inverse and protective effect of HDL levels.
Investigations of blood pressure uncovered a number of misconceptions. It was widely held that women and the elderly tolerated higher pressures well. However, researchers found nothing to suggest that the elderly fared any better than younger persons at a given degree of hypertension. Also, women with high pressures, like their male counterparts, were at increased risk for heart disease.
From the Study: A Better Understanding of Effect of Life Style
Just as Framingham led the way in identifying the underlying risk factors associated with developing cardiovascular disease, it also looked at key elements of the American lifestyle that contributed to the high rates of disease and disability.
Study researchers found that a lifestyle typified by a faulty diet, sedentary living, and/or unrestrained weight gain acerbated disease risk factors and influenced the occurrence of cardiovascular problems.
Before Framingham, cigarette smoking was not accepted as a bona fide hazard in the development of heart disease. The study soon demonstrated that smokers were at increased risk of having a myocardial infarction or experiencing a sudden death. Further, the risk was found to be related to the number of cigarettes smoked each day, and smoking cessation was found to promptly halve the risk compared to those who continued to smoke.
Other Framingham studies demonstrated a protective effect on the heart from even low levels of exercise. And, unrestrained weight gain, accompanied by lack of exercise, was found to promote such cardiovascular risk factors as hypertension and diabetes.
Since its inception in 1948, the Framingham Study has had a profound effect on our understanding of the major risk factors associated with developing heart and vascular disease and stroke. Perhaps as important, the work has stimulated numerous national awareness campaigns educating the American public to the "heart risks" tied to untreated high blood pressure and high cholesterol levels and the dangers of smoking. And, the study has played a seminal role in influencing physicians to place greater emphasis on prevention and detecting and treating cardiovascular disease risk factors in their earliest stages.
Breaking New Ground: The Study Moves Into the Future
Framingham has provided numerous insights into the epidemiology of heart failure, peripheral arterial disease, stroke and arrhythmia. Less appreciated may be the extensive data collected from the aging, original cohort about the prevalence and genesis of dementia, cancer, arthritis, osteoporosis, hearing and eye disorders.
Researchers have progressed from identifying cholesterol as a risk factor in developing heart disease, to distinguishing the unique biologic characteristics of LDL versus HDL, breaking down their apolipoproteins, and, now, they are working to identify the genes that regulate cholesterol metabolism.
Having spent the past 50 years looking at risk factors and lifestyle habits, researchers are now in the forefront of investigating how genes contribute to common metabolic disorders such as obesity, hypertension, diabetes and even Alzheimer's.
In fact, the study has amassed a DNA library of blood samples from two generations of participants -- over 5,000 individuals. The library will help researchers investigate whether and what diseases run in families and identify the genes for a host of serious disorders.
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