Depression is a common condition.
The National Institute of Mental Health (NIMH) estimates that about 10 percent
(one in 10) of American adults experience some form of depression. For people
with chronic illnesses, the number can be higher. For example, NIMH estimates
that about 25 percent (one in four) of people with cancer have depression,
and one study of people with multiple sclerosis found that 41.8 percent
had significant symptoms of depression.
Whether
depression occurs alone or conjunction with a chronic illness, a majority
of people with depression do not seek medical help. However, the NIMH estimates
that therapies available now can alleviate the symptoms of depression in
more than 80 percent of people who get treatment.
As with other types of illness, depression takes different forms. Some of
the most common depressive disorders are:
Major depression,
which is characterized by a set of symptoms that affect a person's work,
sleep, eating habits, and interest in activities he or she once enjoyed.
(For a list of symptoms, please see "How is depression diagnosed?")
To receive a diagnosis of major depression, a person must have several
of these symptoms on most days for at least two weeks. Episodes of major
depression can last for six months or more. Not everyone with major
depression has the same symptoms, nor do their symptoms have the same
severity or duration. People with major depression may have just one
episode of the illness, but more often the symptoms return several times
during their lifetime.
Dysthymia
is a low-intensity mood disorder characterized by similar but less severe
symptoms than major depression, but the condition is longer-lasting
(the symptoms must be present for two years to receive the diagnosis).
While not totally disabling, they make it difficult for a person to
feel good or function normally. Many people who have dysthymia also
have periods of major depression.
Bipolar disorder,
which is sometimes called manic-depressive illness, is much less common
than other types of depressive disorders. It is marked by cycles of
intense highs, called manias, followed by intense lows, or depressions.
While the exact causes of depression are unknown,
several factors appear to affect its onset:
Biochemistry:
Nerve cells in the brain send and receive messages that control your
emotions and feelings as well as all the other complex functions of
your body. Chemicals called neurotransmitters help disseminate these
messages. Scientists believe that symptoms of depression occur when
some of these neurotransmitters, including serotonin and norepinephrene,
are not delivered correctly, causing a chemical imbalance. People with
depression often have either too much or too little serotonin or norepinephrene.
Genetics:
A family history of depressive disorder puts people at greater risk
of developing the illness. But depression also strikes people who have
no family members with the illness. Depression that results from a person's
biology or genetic inheritance is sometimes referred to as endogenous
depression.
Personality:People
who are pessimistic, have low self-esteem or have low tolerance for
stress are more likely to develop depression.
Difficult life situations: Depression may
be more likely in people who are facing smallboldtext problems in their
lives, such as abuse, violence or poverty. Difficult times, such as
divorce, the death of a loved one, financial problems or moving from
your home can also contribute to depression. Depression that results
from such situations is sometimes referred to as reactive depression.
- Other illnesses:
People who have certain other medical conditions are more likely to
develop depression. These conditions include cancer, heart disease,
stroke, diabetes, Parkinson's disease and hormonal disorders.
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