The Heart Disease and Depression Connection
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Over the past 20 years research has demonstrated a relationship between heart disease and depression. Growing evidence shows this relationship is bidirectional, making the diagnosis and treatment of depression an important component in the prevention as well as the treatment of heart disease.
Depression and Recovery from a Cardiac Event
The development of depression in patients who have undergone bypass surgery or had a heart attack is remarkably common, affecting more than one out of five patients. Importantly, studies showed that depression increased the risk of secondary cardiac events including death in these patients. Consequently, in 2008, American Heart Association (AHA) published a scientific advisory recommending that physicians screen for depression in patients with established heart disease. Subsequent studies also showed that the prognosis was worse in depressed patients who have experienced a stroke or heart failure.
Anxiety and Heart Disease
For patients with known cardiovascular disease, much less is known about the association of anxiety with prognosis. Published studies have shown mixed results such as an increased risk of recurrent cardiac events while other studies shown no effect or even a protective effect of anxiety. Results in studies of anxiety may be due in part to the overlap of symptoms of depression and anxiety. Approximately half of major depressive episodes are described as anxious depression because patients may demonstrate symptoms of depression (fatigue, decreased ability to concentrate, feeling sad) as well as symptoms of anxiety (worrying, rumination, health anxieties and panic attacks).
That being said, most experts would agree the presence of depression and anxiety leads to worse outcomes for patients with known heart disease and screening for mood disorders is a reasonable secondary prevention strategy for cardiovascular disease.
Primary Prevention of Heart Disease
What is known about the impact of depression and anxiety in terms of primary prevention of heart disease? In the 2019 AHA Guidelines for the Primary Prevention of Cardiovascular Disease, there are no formal recommendations regarding screening for depression or anxiety as a risk factor for heart disease. This recommendation may be made in the future however given the wealth of emerging data that demonstrates the adverse impact of depression and anxiety on the cardiovascular system and the association of these mood disorders with an increased risk of developing heart disease.
In a meta-analysis that included 30 studies of individuals initially free of heart disease, depression was associated with a 30 percent increased risk of future coronary events. Furthermore, studies suggest depression is more closely associated with heart disease in women than in men, with the strongest effects for younger women.
From a behavioral or risk factor perspective, individuals who are depressed are more likely to engage in unhealthy behaviors such as smoking and skipping medication. They are also more likely to avoid healthy behaviors such as eating a healthy diet or engaging in regular physical activity. All of these behaviors are shown to impact cardiovascular health.
Biological Mechanisms Linking Heart Disease and Depression
A host of biological mechanisms has also been proposed to explain the link between depression and heart disease including increased hormonal signaling and activity, autonomic nervous system reactivity, inflammation, oxidative stress and endothelial dysfunction.
Changes in hormone signaling associated with depression include alterations in stress hormone responses leading to increased cortisol levels. Hormonal changes can also affect the immune system leading to increases in circulating chemical factors related to inflammation. Enhanced inflammation is common in mood disorders and cardiovascular disease.
Brain areas that likely play a role in cardiovascular regulation have also been shown to be altered in patients with depression. Changes in signaling from the brain to the heart may increase the risk of heart arrhythmias including those leading to sudden cardiac death as well as constriction of coronary arteries during stress leading to chest pain.
Finally, studies have also shown patients with depression have an increased activity of blood clot forming cells (platelets). Development of arterial blood clots (thrombosis) can lead to heart attack or stroke.
If you have been diagnosed with mild depression, a multitude of studies have shown that mild depression can often be treated effectively with regular physical activity!
The 2018 Physical Activity Guidelines Advisory Committee Scientific Report, which summarized recent research on regular physical activity, concluded:
- Regular physical activity not only reduces the risk of clinical depression but reduces the severity of those symptoms of depression.
- Regular physical activity reduces symptoms of anxiety, including both chronic levels of anxiety as well as the acute feelings of anxiety felt by many individuals from time to time.
- Strong evidence also demonstrates perceived quality of life is improved by regular physical activity.
So, how can this information help you reduce your risk of developing heart disease or having a second cardiovascular event if you have already been diagnosed with heart disease?
If you have concerns that you may have symptoms of depression or anxiety, talk to your primary care provider. Knowledge is power. You cannot make a plan to treat depression or anxiety unless you know you have it! Regardless of your diagnosis, if you don’t already exercise regularly, get started. Even small steps—such as exercising 10 minutes twice a day and increasing your time gradually—can have big results. What’s good for your heart is good for your brain!
Article provided by Nina B. Radford, MD, Cooper Clinic Cardiologist and Director of Clinical Research.