Are you a Health Professional? Jump over to the doctors only platform. Click Here

Twin Study Indicates Physical Activity Can Counteract Genetic Risk of Artery Disorder

Print Friendly, PDF & Email

While smoking and body fat around the waist are linked to increases in a heart disease risk factor called the Augmentation Index, which is a measure of artery stiffness, physical activity can counteract a genetic predisposition to stiff arteries, according to a new study of healthy female twins in the July 16, 2003 issue of the Journal of the American College of Cardiology.

While smoking and body fat around the waist are linked to increases in a heart disease risk factor called the Augmentation Index, which is a measure of artery stiffness, physical activity can counteract a genetic predisposition to stiff arteries, according to a new study of healthy female twins in the July 16, 2003 issue of the Journal of the American College of Cardiology. The most interesting result from the study was that in high genetic risk twins, regular leisure-time physical activity reduced Augmentation Index values to values not different from the low genetic risk twins. In other words, physical activity ameliorated genetic predisposition to increased arterial stiffness, said Jerry R. Greenfield, MBBS, BSC (MED), FRACP, at St. Vincents Hospital in Sydney, Australia.This study is the first to tease apart lifestyle, physical factors, and genetic influences on the augmentation index, which has been shown to predict heart disease risk and death. By studying twins, the researchers were able to exclude genetic effects when examining the association between lifestyle factors and arterial stiffness. They also were able to determine whether a specific lifestyle variable had different effects in individuals with different genetic risks.By using the St. Thomas U.K. Adult Twin Registry, the largest twin volunteer registry in Britain, the researchers recruited 684 women, including 53 pairs of identical twins, 262 pairs of fraternal twins, and 54 singletons, which means their twin was excluded or had incomplete data. Identical twins develop from the same egg and are genetically identical. While fraternal twins are born at the same time, they share the same proportion of genetic material as non-twin siblings, since they develop from separate eggs. All the participants were healthy; that is, there were no signs of heart disease, stroke, diabetes, or current use of cholesterol-lowering or blood pressure medications.The researchers measured pressure waveforms in arteries in the arm to calculate the augmentation index (artery stiffness) of each participant. They also weighed and measured the women to determine their body mass indexes and body shapes.Dr. Greenfield said the study indicated that being fat around the waist (apple shape, as opposed to pear shape, in which fat is mostly below the waist) was associated with a higher augmentation index.For the first time, the results of the study provide a direct link between accumulation of fat in the abdominal region (measured accurately by a body fat scan) and arterial stiffness, a known measure of heart disease risk and death. The study also demonstrates higher arterial stiffness in smokers and lower stiffness in high genetic risk individuals who exercise regularly, he said.In other words, even women who had a genetic predisposition to an increased augmentation index could keep their values as low as women who had a low genetic risk, if they engaged in regular physical activity.Vera A. Bittner, MD, MSPH at the University of Alabama at Birmingham, who was not connected to this research team, said the study reaffirms that standard risk factors for coronary disease (smoking, high blood pressure, abdominal obesity) relate to arterial stiffness, which in turn is a marker for risk of heart disease and cardiovascular death, but it also provides new insights. It also suggests that there is genetic heterogeneity with a spectrum of risk in the population independent of standard risk factors. Most importantly, however, it suggests that the genetic predisposition to increased arterial stiffness can be modulated by physical activity i.e. a person with a certain genetic background doesn’t have to be fatalistic about their outlook, but can actively lower their risk by lifestyle measures (i.e. exercise), Dr. Bittner said.In addition to St. Vincents Hospital in Sydney, Australia, the research team for this study included the University of Wollongong in Wollongong, Australia; Sequenom in San Diego, California; St. Thomas Hospital in London, United Kingdom; and the Victor Chang Cardiac Research Institute in Sydney, Australia. Dr. Greenfield was supported by a Postgraduate Medical Scholarship from the National Health and Medical Research Council of Australia and Dr. Samaras by the Royal Australasian College of Physicians Diabetes Australia Fellowship. St. Vincents Clinic Foundation, Sydney, Australia supplied funds that supported data analysis. The Twin Research and Genetic Epidemiology Unit, St. Thomas Hospital, London, United Kingdom, is supported by the Wellcome Trust, Chronic Diseases Research Foundation, British Heart Foundation, United Kingdom and Sequenom, San Diego, California.


Print Friendly, PDF & Email

Dates

Posted On: 1 August, 2003
Modified On: 3 December, 2013

Tags



Created by: myVMC