*Depressed mood: An emotional state dominated by feelings of sadness, gloominess, or emptiness, which may be associated with lack of energy. This mood state may be a temporary response to an unhappy or stressful event, or it may be persistent.

*Chronic low-grade depression, also known as dysthymia: Depressed mood is present most of the time for a period of two years, and is accompanied by changes in energy, appetite, or sleep, as well as low self-esteem and feelings of hopelessness. These symptoms cause distress and difficulty in functioning, but are not as severe as in major depression (see dysthymia for further information). People who suffer from dysthymia are at increased risk for episodes of major depression. This produces a situation in which mild depression is present most of the time, with occasional periods of more severe depressive symptoms. This is commonly called "double depression."

*Major depression: Severe, persistent depressed mood and loss of interest or pleasure in normal activities, accompanied by decreased energy, changes in sleep and appetite, and feelings of guilt or hopelessness. These symptoms must be present for at least two weeks, cause significant distress, and be severe enough to interfere with functioning. If the depression is very severe, it may be accompanied by psychotic symptoms or by suicidal thoughts or behaviors (see major depression for more information).

See also major depression; depression in the elderly and adolescent depression.

Most feelings of depression are a reaction to an unhappy event. It is natural to have some feelings of sadness after a loss such as the death of a relative, or after a major disappointment at home or at work. Depression is more prevalent in women than men and is especially common among adolescents.

Mild depression comes and goes and is characterized by downheartedness, sadness, and dejection. Short-term episodes of depression or other mood changes can occur with hormone changes, including those that accompany pregnancy or premenstrual syndrome (PMS), and those occurring shortly after the birth of a baby (postpartum "blues"). Sleep disruption and lack of sunlight during the winter months are other biological factors that can precipitate depressive symptoms.

Distorted thought patterns, characterized by feelings of worthlessness, helplessness, and hopelessness are part of the "cognitive triad of depression," and can be a risk factor for depression.

It appears that a tendency toward depression is often genetic, but that stressful life circumstances usually play a major role in bringing on depressive episodes. Problems with depression usually begin in adolescence, and are about twice as common in women as in men.

Noticeably disturbed thought processes, poor communication and socialization, and sensory dysfunction indicate moderate depression.

People with severe depression are withdrawn, indifferent toward their surroundings, and may show signs of delusional thinking and limited physical activity.

• loss of a friend or relative
• substantial disappointment at home or at work
• prolonged or chronic illness or pain
• medical conditions, such as hypothyroidism, cancer, or hepatitis
• drugs such as tranquilizers, high blood pressure medications, steroids (prednisone), codeine, and indomethacin
• alcohol intoxication
• alcohol withdrawal
• drug intoxication
• drug withdrawal

For mild depressive symptoms, improving health habits to provide adequate and regular sleep and good nutrition may bring relief. Regular exercise is also helpful. Decreasing the use of alcohol and other drugs is also recommended, since these can aggravate depressive symptoms. Involvement in healthy pleasures such as recreation and creative activities, and staying involved with family and friends helps to lift a person's mood.

It is recommended to get support from people in the person's family and social network. Being reminded that other people care helps to relieve the isolation that often accompanies depressed feelings. Discussion with clergy or spiritual advisers may give meaning to painful experiences, and prayer or meditation can access internal sources of strength.

If you recognize that you are chronically pessimistic and self-critical, self-help workbooks to combat depressive thinking may be helpful. These usually involve a program of exercises to identify distorted perceptions and substitute more realistic ones. But when you or a loved one cannot shake these feelings within a few weeks or with help from sources above mentioned, you may need to contact your doctor, because you may be suffering from major depression.

• depression disrupts work and family life for more than two weeks
• depression is so severe that suicide is contemplated. Do not hesitate to call for help immediately! If your primary health-care provider can't be reached, many communities have telephone hotlines for such situations. If there is no such service nearby, call the nearest emergency room or health-care facility
• you think that current medication may be causing depression

A complete history, a psychiatric interview and a physical examination will be performed to determine if the cause of depression is physical or psychological. Hospitalization is usually recommended if suicide seems possible.

Expect some exploration of the issues and events associated with your feelings of depression. Your doctor will ask you in detail about your depressive state and other associated symptoms (sleep, appetite, concentration, energy). He/she will ask you about any current stressors, and support system. You will be asked if thoughts about ending your life have ever crossed your mind. You will also be asked about drug and alcohol use, and about the medications you are currently taking, if any.

Your doctor may recommend medication, but treatment will vary according to the cause and severity of the depressive symptoms, as well as your preference. If you are taking other medications medications that could cause depression, these may need to be changed. DO NOT CHANGE YOUR MEDICATIONS WITHOUT CONSULTING WITH YOUR HEALTH-CARE PROVIDER.

For mild depressive symptoms, counseling may be recommended, as well as some of the self-care measures mentioned above.

For moderate to severe depression, antidepressant medication may be prescribed (see major depression for more information about antidepressants). Psychotherapy may also be recommended. Several types of focused psychotherapies have been developed that are as effective as medication in treating depression. The choice of medications, psychotherapy, or both can be made based on patient's preference and the availability of these treatments. In order to avoid recurrent bouts of depression, it is important to finish the course of treatment.

For people who are so severely depressed as to be unable to function, or who are so acutely suicidal they cannot be safely cared for in the community, psychiatric hospitalization may be necessary.