[The central nervous system, depression and cardiac death]

There is now convincing evidence of a link between depression and cardiovascular death. This evidence comes from prospective studies of healthy populations, and from studies of patients with ischaemic heart disease. It has recently become clear that there is a strong association between smoking and depression. This gave rise to the hypothesis that the association between cardiovascular disease and depression was an artefact due to smoking. The National Health Examination Follow-up Study (NHEFS) settled the question. Three thousand adults without clinical disease at the start of the study were followed up for 12.5 years. After controlling for smoking and other known risk factors, depression was found to be a predictive factor for an increased risk of fatal and non-fatal ischaemic heart disease. Camey et al. in 1988 studied patients rather than healthy subjects, and showed that among patients undergoing coronary angiography, those suffering from major depression had a higher risk of myocardial infarction and of death during the next 12 months than non-depressed patients. Two years later, Ahern et al, found that patients presenting with ventricular arrhythmias following myocardial infarction had a higher risk of death during the following year if they suffered from depression. However, the best study by far is that of Frasure-Smith et al. (1993). They followed up 222 consecutive patients who had suffered a myocardial infarction, and demonstrated that the development of major depression was a significant predictive factor for death during the following 6 months (adjusted risk ratio: 4.29). By the end of 18 months, those patients who had only a slight elevation of the Beck score in the intensive care unit had the same risk of death as those showing symptoms of major depression. As regards the question of whether treatment for depression can alter the risk of death in patients suffering from ischaemic heart disease, and what are the mechanisms underlying these risks, the jury is still out.