Contents:
What is Depression?
Depression is a mood disorder in which feelings of loss, anger, sadness, or
frustration interfere with everyday life. Depression affects approximately 17
million Americans each year. It can be mild, moderate, or severe and occur as a
single episode, as recurring episodes, or as chronic depression (lasting more
than 2 years).
The primary types of depression include:
-
Major depression—five or more symptoms must be present; an episode must last
at least 2 weeks, but tends to continue for 20 weeks. (A mood disorder is
classified as minor depression if less than five depressive symptoms are present
for at least 2 weeks.)
- Dysthymia—a chronic, generally milder form of depression;
symptoms are similar to major depression but more mild in degree
- Atypical
depression—depression accompanied by unusual symptoms, such as hallucinations,
delusions, and physical rigidity
Other common forms of depression include:
- Postpartum depression—experienced by 8% to 20% of
women following delivery
- Premenstrual dysphoric disorder (PDD)—experienced by 3% to 8% of women;
depressive symptoms occur 1 week prior to menstruation and disappear following
menstruation
- Seasonal affective disorder (SAD)—experienced by 5% of adults, the
majority of whom are women; occurs during the fall-winter season and disappears
during the spring-summer season
Depression may also occur with mania (known as
manic-depression or bipolar disorder). In this condition, moods cycle between
mania and depression.
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While it is normal for most people to feel "down in the dumps" on occasion, a
person with major depression feels significantly depressed for a prolonged
period of time, has difficulty enjoying acts that were once pleasurable, and
experiences at least five of the following symptoms for 2 weeks or more:
- Sleep disturbances—at least 90% of people with depression have either
insomnia (sleeplessness) or hypersomnia (excessive sleeping)
- Significant change
in appetite (often resulting in either weight loss or weight gain)
- Fatigue and
loss of energy
- Feelings of worthlessness, self-hate, and inappropriate guilt
- Extreme difficulty concentrating
- Either agitation, restlessness, and
irritability or inactivity and withdrawal
- Recurring thoughts of death or suicide
- Feelings of hopelessness
Although not generally considered to be defining
characteristics of depression, many people with the condition report a lack of
sex drive and sudden bursts of anger.
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The causes of depression are complex and involve a combination of biologic,
genetic, and environmental factors. People with depression may have abnormal
levels of certain brain chemicals, including serotonin, acetylcholine, and
catecholamines (such as dopamine). The following may alter the levels of these
brain chemicals and contribute to development of depression:
- Heredity - a recently identified gene called SERT that regulates the brain
chemical serotonin, has been linked to depression
- Chronic stress (such as from
loss, abuse, or deprivation in early childhood)
- Amount of exposure to light
- Sleep disturbances
- Social isolation
- Nutritional deficiencies (especially folate
[vitamin B9] and
omega-3 fatty acids)
- Serious medical conditions, such as heart
attack or cancer
- Certain medications, including those for high blood pressure,
high cholesterol, or irregular heartbeat
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Reviewed: 03/2006
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