Research over the past two decades has shown that
depression and heart disease are common companions and
what is worse, each can lead to the other. It appears now that
depression is an important risk factor for heart disease along
with high blood cholesterol and high blood pressure. In a
study conducted in Baltimore, it was found that of 1,551
people who were free of heart disease those who were
depressed were four times more likely to have a heart attack
in the next 14 years than those who were not. Researchers in
Montreal found that heart patients who were depressed were
four times as likely to die in the next six months as those
who were not depressed.

Depression may make it harder to take the
medications needed and to carry out the treatment for heart
disease. Depression may also result in chronically elevated
levels of stress hormones, such as cortisol and adrenaline,
and the activation of the sympathetic nervous system (part of
the "fight or flight" response) which can have deleterious
effects on the heart.

The first studies of heart disease and depression showed that
people with heart disease were more depressed than healthy
people. While about one in six people have an episode of
major depression, the number goes to one in two for people
with heart disease. Furthermore, other researchers have found
that most heart patients are not treated for depression.
Doctors tend to miss the diagnosis of depression and even
when they treat it they often treat it with sedatives which may
make the depression worse.

The public health impact of depression and heart
disease, both separately and together, is enormous.
Depression is the estimated leading cause of disability
worldwide, and heart disease is by far the leading cause of
death in the United States. Approximately one in three of
Americans will die of some form of heart disease.

Studies indicate that depression can appear after heart
disease and/or heart disease surgery. In one investigation,
nearly half of the patients studied one week after
cardiopulmonary bypass surgery experienced serious cognitive
problems, which may contribute to clinical depression in some
patients.

There are also multiple studies indicating that heart disease
can follow depression. Psychological distress may cause rapid
heartbeat, high blood pressure, and faster blood clotting. It
can also lead to elevated insulin and cholesterol levels. These
risk factors, with obesity, form a constellation of symptoms
and often serve as a predictor of and a response to heart
disease. Depressed individuals may feel slowed down and still
have high levels of stress hormones. This can increase the
work of the heart. When patients are caught in a fight or flight
reaction, the body's metabolism is diverted away from the
type of tissue repair needed in heart disease.

Regardless of cause, the combination of depression and heart
disease is associated with increased sickness and death
making effective treatment of depression imperative.
Pharmacological and cognitive-behavioral therapy treatments
for depression are relatively well developed and play an
important role in reducing the adverse impact of depression.
With the advent of the selective serotonin reuptake inhibitors
to treat depression, more medically ill patients can be treated
without the complicating cardiovascular side effects of the
previous drugs available. Ongoing research is investigating
whether these treatments also reduce the associated risk of a
second heart attack. Furthermore, preventive interventions
based on cognitive-behavior theories of depression also merit
attention as approaches for avoiding adverse outcomes
associated with both disorders. These interventions may help
promote adherence and behavior change that may increase
the impact of available pharmacological and behavioral
approaches to both diseases.

Exercise is another potential pathway to reducing both
depression and heart disease. Exercise is related to fewer
depressive symptoms in observational studies and appears to
be as efficacious as psychotherapy in patients with mild
depression. Exercise, of course, is a major protective factor
against heart disease as well.

The NIMH and the National Heart, Lung and Blood Institute
are invested in uncovering the complicated relationship
between depression and heart disease. They support research
on the basic mechanisms and processes linking co-morbid
mental and medical disorders to identify potent, modifiable
risk factors and protective processes amenable to medical and
behavioral interventions that will reduce the adverse outcomes