Link between stress and heart disease may be premature

It has often been claimed that psychological stress is an important cause of heart disease, but a study in this week’s BMJ shows that previous research may have been misleading.

Researchers measured self-assessed stress amongst middle-aged Scottish men working in and around Glasgow in the early 1970s. These men were then followed for more than twenty years to see whether or not they developed heart disease. Several different measures of heart disease were used.

Men who thought they were most stressed were also most likely to report symptoms of ill health, including symptoms of angina. In some cases, these symptoms also led to hospital admission. A naïve analysis would therefore apparently show that stress causes heart disease. However, hospital diagnoses of heart disease, electrocardiogram (ECG) signs of heart disease and death from heart disease (and in fact overall death rates) were actually lower amongst men reporting high stress.

“It seems unlikely that genuine coronary heart disease would not be associated with an increased risk of heart disease death in a middle aged male population followed up for over 20 years,” say the authors.

They suggest a more likely explanation is that some people see themselves as experiencing more symptoms of stress, and also more symptoms of illness. This may have led past researchers to wrongly conclude that stress causes heart disease.

Interestingly, the men who saw themselves as most stressed in this study, also smoked more, drank more alcohol and took less exercise. However, most stressed men tended to have better jobs. This greater affluence probably explained why, by most objective measures of heart disease, they were healthier.