[The role played by the autonomic nervous system in the relation between depression and cardiovascular disease]

Findings from several epidemiological studies have revealed that major depression is associated with an increased risk of developing cardiovascular diseases (CVD) and presenting complications and new events in subjects with already-established CVD. The pathophysiological mechanisms responsible for this increased cardiovascular risk in major depression remain unclear.

The aim of this work is to review the literature on the possible pathophysiological mechanisms involved in the relation between major depression and CVD, with special emphasis on the studies dealing with cardiovascular autonomic dysfunction and heart rate variability. Likewise, recent hypotheses concerning the neural mechanisms underlying autonomic dysfunction in subjects with major depression are also discussed.

The evidence that is currently available allows us to hypothesise that there are anomalies in the functioning of the central autonomic neural network in subjects with major depression, and more specifically in the hippocampus, prefrontal cortex and the brain stem nuclei. Such abnormalities, in association with lower central levels of serotonin give rise to a predominance of the sympathetic flow and a loss of cardiac vagal tone. The resulting cardiovascular autonomic dysfunction could be the main cause of the increased cardiovascular risk observed in major depression. In the future, studying the autonomic nervous system may be a useful tool in the development of new therapeutic strategies aimed at reducing cardiovascular morbidity and mortality in subjects with depression.