Scientists closer to link between stress and heart disease

British researchers believe they are closer to proving what has long been suspected, that there is a link between work or financial stress and heart disease. Equally important is their finding that reducing stress – like stopping smoking – reverses the dangers of developing the illness.

A team from University College London examined the biological effects of stress in 183 men aged 45 to 63, focusing on how much control they had in their work and their perceived wealth. That showed a link with "metabolic syndrome", thought to be a precursor to coronary heart disease.

Dr Eric Brunner, who led the research at the department of epidemiology and public health, said: "There's a widespread perception that stress is known to cause heart disease, but in epidemiological terms there's a lot of argument about it." No such link has been proved, although sudden intense stress, such as the death of a close relative, can induce an acute attack. That does not show what caused the heart disease originally.

"This study provides biological and therefore more objective evidence than before of the link between stress and metabolic syndrome," Dr Brunner said. "Although this is not concrete proof that stress causes metabolic syndrome or indeed heart disease, we are certainly closer to proving it."

One possibility is that our bodies have not evolved at the same pace as we have moved to urban life, he suggested. "We evolved for the fight or flight syndrome, but without control in our work we don't have that. Modern urban life might be considered toxic to our evolved physiology."

People with metabolic syndrome display a combination of at least three symptoms from obesity, high blood pressure, high blood sugar, raised levels of triglycerides and low levels of HDL, or so-called "good" cholesterol.

Fat in food and the body is stored as triglycerides, which are also found in blood with cholesterol. Raised cholesterol levels are risk factors for coronary heart disease and strokes. High triglyceride levels can increase the risk of coronary heart disease and stroke.

The men in the study were questioned about how much responsibility and control they had in their jobs, as well as their intensity. Their alcohol and tobacco consumption, exercise and diets were also analysed. The results showed men with metabolic syndrome produced more stress hormones such as adrenalin and cortisol, because of psychosocial factors such as job strain. They were also found to be more obese and have abnormal heart rates.

But the researchers said they were encouraged that the biological effects of stress were partly reversible in men who reduced their risk factors by losing weight or lowering their blood pressure. Dr Brunner said he was happy to be close to demonstrating the link. "It's elusive because heart disease takes a lifetime to develop, and to show this link you have to exclude the possibility that it's down to what people eat and how they exercise."

Professor Sir Charles George, medical director at the British Heart Foundation, which helped fund the study, said: "The link between stress and heart disease is still unclear but this study is significant as it helps us to understand more about the relationship between the conditions. Although more research is needed, this is an important step forward."