Though we’ve known about the connection for some time, a large-scale study hints at the degree to which depression may increase the risk of future heart disease. Looking at data from almost 63,000 people in Norway, and following up over 11 years, the researchers found that mild depression was linked to a 5% increase in the risk of heart failure in the future. Moderate to severe depression was linked to a surprisingly high 40% rise in the risk.
The research was presented at the annual meeting of the European Society of Cardiology’s Council on Cardiovascular Nursing and Allied Professions (CCNAP). It has not been published in a peer-reviewed journal, so should be considered preliminary.
Still, the early results are worth paying attention to. “We found a dose response relationship between depressive symptoms and the risk of developing heart failure,” said study author Lise Tuset Gustad. “That means that the more depressed you feel, the more you are at risk.”
Gustad points out the caveat that depression can severely affect a person’s interest in certain activities – like exercising, losing weight, quitting smoking, or eating well, all of which increase heart risk. In light of this issue, the team’s calculations corrected for these variables, and found that the depression-heart risk connection was still strong. Gustad says that she and her team “can be confident that these factors did not cause the association.”
So why the connection between the brain and the heart? One theory, say the researchers, is that depression increases the levels of stress hormones, which could, over time, lead to inflammation, a known risk factor for heart disease. “If you’re stressed you feel your pulse going up and your breath speeding up, which is the result of hormones being released,” said Gustad. “Those stress hormones also induce inflammation and atherosclerosis, which may accelerate heart diseases.”
But there are likely other mechanisms at play. Existing problems in the function of the stress response could underlie both depression and heart disease, rather than the one leading to the other. Genetic factors are also likely to play roles in the development of both. Oxidative stress might be another factor; so could hormone dysfunctions. The relationship is not clear-cut, and it will be an ongoing effort to tease apart which one leads to the other, or whether other variables exist that affect the risk of both.
And with many studies like this one, causation can’t be determined – only a connection. So it’s not fair to say that depression causes heart disease, only there is a relationship between the two.
Whatever the connection, which we won’t fully understand for a while, it’s always best to get treated if you’re experiencing depression. “The early symptoms of depression include a loss of interest and loss of pleasure in things that have normally been interesting or given pleasure.” says Gustad. “If you feel like that, speak to your friends and if it lasts for a month see your doctor or nurse. Depression can be treated easily in the early stages and many people don’t need medication. Talking to a professional may be all you need.”
It may not be all you need, but it’s a start. Finding the right combination of methods is usually the more effective answer.