Relationship between depression and heart disease

Scientists have long observed an association between depression and heart disease. Depressed adults have a 66% greater risk of developing coronary artery disease. These patients are also more likely to progress to serious outcomes such as a heart attack – at least a quarter of cardiac patients suffer with depression. 

What exactly is happening?

Is depression a risk factor for heart disease or does heart disease make people depressed? 

The evidence suggests that the answer is both. This helps explain the reduced life expectancy of people with depression – a fact that was once blamed on suicide.  

The association is also far from trivial with depression being the strongest predictor of death in the first decade after a diagnosis of heart disease – even more than smoking! 

Most curiously, the link with depression and heart disease seems to be independent of the traditional risk factors such as high cholesterol, hypertension, or diabetes.  Yes, being depressed leads people to eat poorly, exercise less and take up other unhealthy habits. But, depression itself appears to be a risk factor for heart disease on its own. 

How does depression do this?

While the precise mechanism remains obscure, we know that depression affects the autonomic nervous system which leads to changes in heart rate and blood pressure. Inflammation is also involved with elevated levels of attack molecules roaming the circulation.

Depression can lead to insulin resistance as seen in diabetes as well as making platelets more reactive which paves the way for the clots of strokes or heart attacks.  

The common element of these changes is the body’s emergency systems switched on too long. The end result – damage to delicate blood vessels.

This crucial observation has led researchers to investigate whether treating depression reduces heart disease just like treating high cholesterol or blood sugar.  

The answer appears to be a resounding yes: targeting depression early can slash the risk of strokes and heart attacks by almost half.  Just as important is prompt treatment of depression in those who already have heart disease.

Discovering the link between depression and heart disease makes diagnosis and treatment of depression even more urgent with the chance to improve not just quality of life, but length of life.

REFERENCES

Patel, J. S., Berntson, J., Polanka, B. M., & Stewart, J. C. (2018). Cardiovascular Risk Factors as Differential Predictors of Incident Atypical and Typical Major Depressive Disorder in US Adults. Psychosomatic medicine, 80(6), 508–514. https://doi.org/10.1097/PSY.0000000000000583

David L. Hare, Samia R. Toukhsati, Peter Johansson, Tiny Jaarsma, Depression and cardiovascular disease: a clinical review, European Heart Journal, Volume 35, Issue 21, 1 June 2014, Pages 1365–1372, https://doi.org/10.1093/eurheartj/eht462

Musselman DL, Evans DL, Nemeroff CB. The Relationship of Depression to Cardiovascular Disease: Epidemiology, Biology, and Treatment. Arch Gen Psychiatry. 1998;55(7):580–592. doi:10.1001/archpsyc.55.7.580