Depression and heart disease are two of the most common health disorders in the U.S.  Now, research studies are revealing they're often common companions as well.

While the research is not definitive, it points to the premise that each may be a cause – or an effect – of the other.  In other words:

• People who have heart disease are more likely to suffer from depression
• People who are depressed may be at greater risk for developing heart disease

Additionally, people with heart disease who are depressed have an increased risk of death after a heart attack.

While researchers are still studying how depression might trigger heart problems, they have identified several mechanisms as potential culprits.

• People with depression typically have decreased heart rate variability, which may cause dangerous heart arrhythmias or variations in blood pressure.
• Mental distress seems to encourage platelets to clump together, creating an increased potential for the formation of blood clots.
• Depressed people are more likely to develop well-known risk factors for heart disease such as hypertension, dyslipidemia, insulin resistance or glucose intolerance.
• Increased levels of inflammatory proteins commonly found in patients with depression have been clearly linked to increased risk of heart attack.
• Chronically elevated levels of stress hormones, such as cortisol and adrenaline can increase the work of the heart.
• In the chronically stressed and depressed individual, the repair and healing systems of the body may be compromised.

Despite the research findings, depression often goes under diagnosed and under treated for a variety of reasons. 

• Many people still view a mood disorder as a personal failure or a sign of personal weakness and are unwilling to tell their doctors about it.  Conversely, some doctors are reluctant to raise the subject with patients. At times, both doctors and their patients agree that "depression is natural" when someone has chronic illnesses, and thus tend to ignore its impact or fail to treat it adequately. Men, in particular, are less likely than women to reach out or admit they may be distressed, demoralized, or sad.
• When patients report physical signs of depression, such as fatigue, headaches or changes in eating and sleeping patterns, physicians tend to focus on physical causes. 
• After heart disease is diagnosed, doctors may interpret a patient's sadness, loss of joy and interest, sense of pessimism or hopelessness, demoralization, poor concentration and forgetfulness as a normal consequence of serious illness. One or several of these symptoms may be present fleetingly, but when sustained, they cannot be passed off as "just a reaction."