DEPRESSION and heart disease are often associated and each apparently can lead to the other, according to data accumulated over the past 25 years.

It is becoming more evident that depression is indeed an important risk factor for heart disease along with diabetes, high cholesterol, smoking, and hypertension. As much as 15 per cent of patients with cardiovascular disease and about 20 per cent of patients who have undergone major cardiac surgery experience major depression.

A study of 1,551 individuals without heart disease showed that those who had a history of depression were four times more likely than those without a history of depression to suffer a heart attack in the next 14 years. Researchers have also found that heart patients with depression were four times more likely to die in the next six months, when compared to those without depression.

In addition, patients with depression are more likely to have chronically sustained increase in levels of stress hormones and also to be non-compliant with their recommended treatment for heart disease, complicating therapeutic options and having deleterious effects on the heart. Increased stress hormone levels seen in depressed patients have also been associated with increased risk of developing high blood pressure, arterial damage and irregular heart rhythms. Arterial damage predisposes individuals to blood clots and increased risk of heart attacks.

Major depression occurs in about one in 20 American adults in any given year. That number increases to about one in three for people who have survived a heart attack. Given the weight of evidence supporting depression as a significant risk factor for heart disease, the American Heart Association (AHA) has recommended that all cardiac patients be screened for depression using simple screening questions. The AHA had also recommended in a 2008 statement that depression be formally considered a risk factor for increased heart disease.

Depression may also be a hidden heart disease risk factor for women under the age of 55 years. Women 55 years and younger who are depressed are twice as likely to have a heart attack, die or require artery-opening procedures, according to new research published in the Journal of the American Heart Association. Researchers evaluated depression symptoms in 3,237 people with heart disease who were scheduled for coronary angiography, an X-ray that diagnoses disease in the arteries supplying blood to the heart. After a follow-up period of about three years, they found that an increase in depression symptoms was associated with a significant increase in heart disease in women 55 years and younger, after adjusting for other heart disease risk factors.

Studies indicate that depression can appear after heart disease and/or heart disease surgery. In one investigation, about 50 per cent of patients evaluated one week after heart bypass surgery experienced serious cognitive problems, which is thought to contribute to clinical depression. For people with heart disease, depression may increase the risk of adverse outcomes such as heart attacks or blood clots. For people who do not have heart disease, depression can also increase the risk of a heart attack and development of coronary artery disease. In one major study, the persistence of depression after recovery from heart attack increased the risk of death by up to 17 per cent within six months after a heart attack, nearly six times the rate for heart attack patients without depression.

The public health impact of depression and heart disease, independently and jointly can be devastating. While depression is the presumed leading cause of disability worldwide, heart disease is by far the leading cause of death in most countries.

Irrespective of cause, the combination of depression and heart disease is associated with increased risk of death and disability, and should demand urgent attention. Competent medical evaluation should be encouraged to determine best treatment options.

Increased social interactions and exercise should be encouraged as potential pathways to reducing both depression and risk of heart disease.

Professor Ernest Madu, founder of the Heart Institute of the Caribbean, is an internationally acclaimed cardiologist and expert on innovative health solutions. HIC is a centre of excellence for cardiovascular care in the English-speaking Caribbean. Please send questions and comments to emadu@caribbeanheart.com.