The exact cause of depression is not known. Some researchers think that it may be caused by chemical imbalances in the brain, which may be hereditary or caused by events in a person's life.

Some types of depression seem to run in families, but depression can also occur in people who have no family history of the illness. Stressful life changes or events can also trigger depression in some people. Usually a combination of psychological, environmental, and hereditary factors are involved in the development depression.

Major depression occurs in all groups of people, and it is more common than you might realize. Each year, more than 18 million Americans -- men and women of all ages, races, and economic levels -- suffer from depression. It occurs more often in women.

Many women are especially vulnerable to depression after giving birth as a result of the hormonal and physical changes that they have experienced. While new mothers may commonly experience transitory "blues", depression is not normal and requires treatment.

Depression can also be seen in adolescents and children, and they can also benefit from treatment.

• Persistent sadness lasting greater than 2 weeks.
• Loss of interest or pleasure in activities that were once enjoyed (including sex).
• Loss of appetite or weight loss, or overeating and weight gain.
• Sleep disturbances.
• Energy loss or fatigue.
• Behavior that is either slowed down or restless.
• Feelings of worthlessness, hopelessness, and pessimism.
• Difficulty concentrating, making decisions, and remembering.
• Thoughts of death or suicide.
• In some cultures, physical discomfort, weakness, and "nerves" may be the most prominent symptoms.
• In children and adolescents, mood is more likely to be irritable (see adolescent depression).
• If depression is quite severe, it may be accompanied by psychotic symptoms, such as hallucinations and delusions. These are usually consistent with the depressed mood, and may focus on themes of guilt, personal inadequacy, or disease.
• Depression can also appear as irritability, anger, and discouragement rather than feelings of hopelessness and helplessness.

• The history of persistent sad mood, loss of interest or pleasure in activities that were once enjoyed, and several of the additional symptoms listed above, are required to make the diagnosis of depression.
• The Beck's Depression Scale Inventory, or other screening tests for depression can also be helpful in diagnosing depression.
• Medical causes that can show symptoms of depression should also be ruled out before making the diagnosis of depression.

Depression can be treated with medications and/or with counseling. Most people benefit from a combination of the two. Some studies have shown that antidepressant drug therapy combined with psychotherapy appears to have better results than either therapy alone.

Medications include: tricyclic antidepressants, monoamine oxidase inhibitors, selective serotonin re-uptake inhibitors (SSRIs), and some newer antidepressant drugs. Lithium and thyroid supplements may be needed to enhance the effectiveness of antidepressants. For persons with psychotic symptoms, such as delusions or hallucinations, antipsychotic medications may be needed.

One major antidepressant, Paxil, now has a warning NOT to be given to children under 18.

Types of psychotherapy that have proven to be particularly effective for treating depression include interpersonal therapy, group therapy and cognitive/behavioral therapy. Antidepressant drug therapy combined with psychotherapy appears to have better results than either therapy alone.

Electroconvulsive therapy (ECT) is a treatment that causes a seizure by means of an electrical current. ECT may improve the mood of severely depressed or suicidal people who don't respond to other treatments.

Research is now being conducted on transcranial magnetic stimulation (TMS), which alters brain functioning in a way similar to ECT, but with fewer side effects. Use of light therapy for depressive symptoms in the winter months and interventions to restore a normal sleep cycle may be effective in relieving depression.

As treatment takes effect, negative thinking diminishes. It takes time to feel better, but there are usually day-to-day improvements. It is important to maintain a healthy lifestyle, including good nutrition, avoidance of alcohol and drugs (which make depression worse and may interfere with medications), regular exercise and sleep, and involvement in supportive interpersonal relationships.

Over the last decade, the use of herbal products has increased tremendously. Most consumers use herbal products for management of chronic conditions, such as psychiatry disorders, including anxiety and depression.

St. John's wort has a long history of use in Germany and has gained popularity as an herbal antidepressant in the United States. Most of the German studies indicated that St. John's wort was comparable to tricyclic antidepressants.

However, a large study conducted by the National Center for Complementary and Alternative Medicine found that St. John's wort was NOT effective for treating major depression. (Results were published in April 2002.)

Because herbal products can have side effects, always tell your doctor if you are using any.

For more information and resources, seee depression support group.

The outcome is usually good with treatment. Although most depressive episodes can be effectively treated with either medication, psychotherapy, or both, depression is a recurring problem for many people. For people who have experienced repeated episodes of depression, maintenance treatment may be needed to prevent future recurrences.

• Suicide (up to 15% of people with major depressive disorder die by suicide)
• Increased risk of alcohol- and/or drug-related problems
• Increased risk of tobacco dependence
• Increased risk of problems with physical health and premature death due to medical illness

Some episodes of depression can be avoided by:

• learning hwo to manage stress
• avoiding overuse of alcohol, drugs, and caffeine
• exercising regularly
• maintaining good sleep habits

Many episodes of depression are not preventable. Treatment, including medications and psychiatric intervention, may prevent recurrences.