Sometimes life can get you down. The loss of a loved one, a serious health problem, job changes, moves or a big disappointment can all get people down in the dumps. But if you find that after a couple of weeks you just can't seem to snap out of it, you might have clinical depression.

Depression affects more than 20 million Americans each year and one in four women and one in 10 men have a serious episode of depression during their lifetime. Even though depression is so common, many people blame themselves for having this illness. They view their feelings as weaknesses and chide themselves for not being stronger, happier and better.

The good news is that nearly all of those who suffer from depression can be helped. Doctors know much more about treating depression today than they did years ago. Eighty to 90 percent of all people who are treated obtain relief from symptoms.

Factors that can trigger depression

People don't recognize depression as an illness. They think the physical symptoms they experience - fatigue, change of appetite and sleep problems - are signs of another kind of illness. Still others think these problems are "all in their head" and that nothing's really the matter with them.

But depression is a brain disorder that affects your whole body -- your behavior and mood, the way you think and the way your body feels. Although scientists do not know the exact mechanism that triggers depressive illness, some pieces of the puzzle include:

• Genetic factors. Some types of depression may be caused by your genes. Some studies have found a link with depression in biological families that was not found in families with adopted children. More recent genetic research offers hope that scientists soon may be able to identify a genetic marker that indicates a susceptibility to bipolar disorder in some people.
• Chemical imbalances. Additional research suggests people suffering from depression have imbalances in the natural substances that allow brain cells to communicate with one another. Other research shows alterations in body chemicals and hormones in depressed people. But researchers are uncertain whether these imbalances are causes of depression or result from it.
• Life stresses. Any kind of life change, good or bad, can sometimes trigger depression. A job promotion can prompt a bout of depression as easily as a job loss. The birth of a child may be followed by depression, as is the loss of a loved one.
• A serious illness. Depression may be caused by certain medications, such as pain relievers for arthritis, and certain medications for high blood pressure and heart problems. Thyroid disease also has been linked to depression.
• Substance abuse. Experts believe 25 percent of people with substance abuse problems also have major depression. Drugs and alcohol provide a way for people to medicate themselves yet can lead to a downward spiral that can be stopped with appropriate help.

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