Depression, Inflammation, Sleep, and Heart Disease

Approximately 15% of people with cardiovascular disease and up to 20% of people who have undergone coronary artery bypass graft surgery experience major depression. Major depression is diagnosed when someone has experienced a number of depressive symptoms, such as sad mood, inability to enjoy things one used to enjoy (anhedonia), feelings of guilt, and changes in eating or sleep, daily for at least two weeks.

A link between depression and heart disease was first described in the 1980s. Research has shown that depression is a more significant risk factor for having additional cardiovascular events, such as another heart attack, than even heredity, smoking, and other lifestyle factors. In addition, depression following a heart attack has been associated with an increased risk of death.

Depression and Inflammation
Both depression and cardiovascular disease (CVD) are associated with increased inflammation. Until recently, however, it was unclear whether inflammation led to depression in those with CVD or whether depression led to increased inflammation in this population. A new study by Dr. Mary Whooley and colleagues at the University of California San Francisco has shed light on this relationship.

Earlier research had shown that higher white blood cell (WBC) count, a measure of inflammation, is associated with increased risk of atherosclerosis or hardening and narrowing of the arteries. Higher WBC counts also are linked to increased risk of cardiac mortality. The investigators sought to better understand the relationship between depressive symptoms and WBCs.

The team followed 667 participants who were enrolled as part of a larger, ongoing study, and assessed their levels of depressive symptoms and WBC counts over the course of a five-year period. What they found was that 21% of participants had significant symptoms of depression at two or more of the five annual evaluations. Recurrent depressive symptoms were associated with significantly greater inflammation as measured by WBC. This effect was independent of factors normally associated with higher risk of cardiac events, including age, gender, education, race, history of diabetes, heart attack, congestive heart failure, cardiac disease severity, aspirin use, physical activity, smoking, and baseline WBC count.

Poor Sleep Quality and Inflammation
Interestingly, participants’ sleep quality seemed to explain the relationship between depression and inflammation. The team concluded that depression may lead to sleep disturbance, and this in turn may increase both inflammation and the likelihood of worse heart health.

Why Is This Important?
The reason for the association between sleep and inflammation in depressed participants with CVD is unclear; however, one possibility is that chronic stress causes the bone marrow to overproduce white blood cells, and this effect may be more pronounced in those with sleep disturbances. These findings are important because previous studies have shown that elevated WBC count is a predictor of new cardiac events and cardiac death. If depression and poor sleep predict inflammation, these findings highlight the need to routinely assess mood and sleep in people with CVD and to treat these issues promptly.

What Can You Do?

• Work with your medical team to create a healthy lifestyle plan that includes exercise and good nutrition. Both of these can help with mood, overall and cardiac health, and sleep quality.
• Practice good stress management, including meditation. Meditation has been shown to help normalize blood pressure in people with hypertension, and it can also help one to notice distressing thoughts and feelings without getting carried away with or overwhelmed by them. A recent study also has found mindfulness meditation to help with insomnia.
• Develop a good social support network. Reconnect with friends, family, or members of your religious community. If your network is limited, identify activities you have always wanted to engage in, such as joining a book club or taking a class. Use these as opportunities to begin meeting people who share similar interests. Social support is vital during recovery from serious illness.
• See a professional. Psychotherapy, especially approaches that are interpersonally oriented, has been shown to be beneficial for those who have had a cardiac event.
• Consider an antidepressant medication. Selective serotonin reuptake inhibitors (SSRIs) can be effective and are generally considered safe for people with CVD. A consultation with a psychiatrist who has worked with people with CVD can help you determine whether an antidepressant medication is appropriate.

References:

1. Duivis, H. E., et al. (2013). Depressive symptoms and white blood cell count in coronary heart disease patients: Prospective findings from the Heart and Soul Study. Psychoneuroendocrinology, 38(4), 479-487.
2. Cleveland Clinic: “Depression and Heart Disease” http://my.clevelandclinic.org/heart/prevention/stress/depressionandheart.aspx
3. DiscoveryHealth.com: “Can Depression Cause Heart Attacks?” http://health.howstuffworks.com/mental-health/depression/questions/depression-cause-heart-attack.htm
4. National Institute of Mental Health: “Depression and Heart Disease” http://www.nimh.nih.gov/health/publications/depression-and-heart-disease/depression-and-heart-disease.shtml

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