People with major depression and anxiety are 75% more likely to have a heart rate condition linked to cardiovascular disease regardless of whether they are taking antidepressants, new research shows.
Until now, studies have reported reduced heart rate variability in depressed patients, and also established links between that condition and premature aging, disease and death. But there has been debate about whether these effects are caused by medication, a prior history of cardiovascular disease, or the depression itself.
Tests by a team of Australian researchers from four universities found that patients who were not taking antidepressant medication and who were otherwise physically healthy continued to show a clinically-relevant reduction in heart rate variability.
The findings, published yesterday in the journal PLoS ONE, highlight the need to consider the physical health of otherwise healthy patients with depression, said one of the authors, Dr. Andrew Kemp, from the University of Sydneys School of Psychology.
They show that patients with both depression and anxiety may benefit from cardiovascular risk reduction strategies. In particular, they should stop smoking and reduce their alcohol intake.
A range of studies have shown that people with a more variable heart rate are better able to respond and adapt to challenges because their cardiovascular system is more flexible.
People who have a reduced heart rate variability, on the other hand, have trouble responding to changing environmental circumstances and physiological demands. This means they are more likely to feel threatened even when there is no danger in their surroundings.
The study of 73 patients with major depression also found that 24 of the subjects, who also suffered from general anxiety disorder, were most at risk.
Participants had no history of drug addiction, alcoholism, neurological disorder or other medical conditions, and all were free from antidepressants.
We suggest that the effects may be due to worry and hypervigilance, leading to chronic changes in heart function that increase the risk for a variety of conditions including cardiovascular disease, Dr. Kemp said.
Dr. Christopher Davey, a consultant psychiatrist at Orygen Youth Health in Melbourne, said that the research was important because we have come to understand in recent years that depression is a significant risk factor for heart disease, with some research suggesting it is as big a risk factor as things like smoking and hypertension.
Depression is not simply a psychological illness. And what this research highlights is that depression also affects the function of the heart, even when someone doesnt yet have any evidence of heart disease.
He said the paper underscored the importance of getting prompt and thorough treatment for depression, because it would not only help to alleviate the symptoms but also potentially reduce their risk of heart disease later in life, he said.