Depression is Causal Risk of Coronary Heart Disease

Symptoms of depression may be causally linked to the risk of coronary heart disease (CHD), according to new research. A team of investigators including researchers from University College London in the United Kingdom analyzed data of 10,308 civil servants in the U.K. who were a part of the Whitehall II study, in an effort to determine whether there is any evidence that the likelihood or severity of depressive symptoms are a direct cause of vascular events—known as a “dose-response” effect. All participants underwent clinical examination and were required to complete a 30-item general health Questionnaire. Researchers followed up with all subjects for 20 years, during which time health assessments were carried out every 2 years to 3 years. Any stroke or CHD events were recorded as well. Participants were also measured for their "exposure" to depression on six separate occasions. Researchers found that participants who showed depressive symptoms in the first 1 or 2 assessments demonstrated no increased risk of CHD. Those who had symptoms of depression in the third or fourth assessments, however, showed a 100 percent increase in risk of CHD. The researchers also note that the link between depressive symptoms and stroke only appeared after a short follow-up period, suggesting the link between depression and stroke is a reverse causation effect. In addition, investigators said they found no evidence of a dose-response effect with stroke, indicating that depressive symptoms are not a cause of vascular disease as related to a stroke, but they are a consequence. The team notes that some studies in dispute of the association may be biased as a result of “reverse causation,” meaning that vascular disease has not been deemed as the consequence of depressive symptoms, but as the influence. Furthermore, the investigators question the accuracy of depressive symptoms assessed in previous research. “The new study adds to evidence that depression is a risk factor,” says Eric Brunner, MD, reader in the department of epidemiology and public health at University College London, and lead study author. “Physicians need to consider the mental health of the patient in identifying optimal vascular risk lowering, and to consider whether their depressive symptoms should be addressed.” —Mark McGraw Reference Brunner E, Shipley M, et al. Depressive Disorder, Coronary Heart Disease, and Stroke: Dose–Response and Reverse Causation Effects in the Whitehall II Cohort Study. European Journal of Preventive Cardiology. 2014.