You wouldn’t necessarily think that a common mental disorder and a life-threatening physical ailment would have much in common. But, as it turns out, depression and heart disease are connected in multiple ways. Let’s look at their similarities and see if anything can be done to treat people with both conditions.
There is clearly an association between depression and heart disease but due to a lack of research, most experts stop short of saying that one causes the other.
Does Depression Lead to Heart Disease?
- Depression is a predictor of heart disease in otherwise healthy people. Adults with depression have a 64% greater risk of developing coronary artery disease. What’s more, depressed patients with heart disease are 59% more likely to have a future negative cardiovascular event, such as a heart attack.
- According to researchers at the Intermountain Medical Center Heart Institute in Salt Lake City, depression is the strongest predictor of death in the first decade following a diagnosis of heart disease. Depression actually doubles the risk of death after a heart disease diagnosis. Many of the reasons appear behavioral; depressed individuals are less motivated to take care of themselves.
- The good news is that depressed people that received treatment for depression before the development of heart disease decreased the risk of heart attacks and strokes by almost half.
Does Heart Disease Lead to Depression?
Less clear is whether heart disease can lead to depression. On its face, it is not hard to imagine that having heart problems could bring about depressive symptoms, but the research is not as robust.
- It has been estimated that about one in five people with no history of depression become depressed after heart failure. It should be noted that even a 20% chance of depression is more than double what is found in the general population.
- Additionally, two researchers at Indiana University-Purdue University Indianapolis found that 20-30% of people are found to develop depression soon after a heart attack.
Depression and heart disease share certain biological mechanisms possibly indicating their relationship at a physiological level.
Platelets, which are integral in blood clotting, are also rich in serotonin, which is implicated in depression. There is some evidence that the clumping together of platelets (which can cause a heart attack or stroke) is related to higher levels of depression. Further, anti-depressants have been found to be able to break up clumped-together platelets.
Inflammation has long been linked with heart attacks and strokes. Inflammation occurs when our bodies produce chemicals to fight infections, stress, and lifestyle factors such as smoking and drinking. Although this is an adaptive response, chronic inflammation can lead to atherosclerosis (i.e., a buildup of fatty plaque in the arteries). High levels of these inflammation markers are present in treatment-resistant depression and appear to be predictive of depressive episodes.
Omega-3 Polyunsaturated Fatty Acids
Low levels of omega-3 acids (commonly found in fatty fish) have been associated with both heart disease and depression. There is an inverse relationship between omega-3s and heart attacks. Additionally, depressed patients with heart disease exhibit lower plasma levels of omega-3s.
Although treatment for depression may prevent future occurrences of heart disease, their impact on people who already have heart disease is not as definitive.
Selective serotonin reuptake inhibitors (SSRIs) have begun to be explored as a treatment for people who have both depression and heart disease. Sertraline and citalopram (i.e., Zoloft and Celexa) in particular have shown some promise. The use of sertraline, for instance, has been associated with a reduction of platelet clumping, suggesting that the use of antidepressant medications might improve platelet function.
It is difficult to tease out the effects of psychotherapy on depressed patients with heart disease because almost all available research combines psychotherapy with medication in its evaluation. That said, a mixture of psychotherapy and medication, while reducing depressive symptoms, has not yet shown the ability to significantly decrease cardiac events, such as a heart attack or stroke.
There is evidence to suggest that exercise significantly reduces depression in people with milder depressive symptoms. Further, it is known that exercise improves outcomes for people with heart disease, including a reduction in fatal incidents.
There is More To learn
There is little doubt that depression and heart disease are related, but the investigation into their association is still in its infancy. Despite sharing certain biological similarities, such as inflammation and platelet activity, more research into their common etiology is required. Although current treatments show promise, the effectiveness of interventions for depressed patients with cardiovascular problems is largely in need of further study.