A depressive disorder is an illness that involves the body, mood, and thoughts. It affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. A depressive disorder is not the same as a passing blue mood. It is not a sign of personal weakness or a condition that can be willed or wished away. People with a depressive illness cannot merely "pull themselves together" and get better. Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people who suffer from depression.

Depressive disorders come in different forms, just as is the case with other illnesses such as heart disease. This pamphlet briefly describes three of the most common types of depressive disorders. However, within these types there are variations in the number of symptoms, their severity, and persistence.

Major depression is manifested by a combination of symptoms (see symptom list) that interfere with the ability to work, study, sleep, eat, and enjoy once pleasurable activities. Such a disabling episode of depression may occur only once but more commonly occurs several times in a lifetime.

A less severe type of depression, dysthymia, involves long-term, chronic symptoms that do not disable, but keep one from functioning well or from feeling good. Many people with dysthymia also experience major depressive episodes at some time in their lives.

Another type of depression is bipolar disorder, also called manic-depressive illness. Not nearly as prevalent as other forms of depressive disorders, bipolar disorder is characterized by cycling mood changes: severe highs (mania) and lows (depression). Sometimes the mood switches are dramatic and rapid, but most often they are gradual. When in the depressed cycle, an individual can have any or all of the symptoms of a depressive disorder. When in the manic cycle, the individual may be overactive, overtalkative, and have a great deal of energy. Mania often affects thinking, judgment, and social behavior in ways that cause serious problems and embarrassment. For example, the individual in a manic phase may feel elated, full of grand schemes that might range from unwise business decisions to romantic sprees. Mania, left untreated, may worsen to a psychotic state.

Some types of depression run in families, suggesting that a biological vulnerability can be inherited. This seems to be the case with bipolar disorder. Studies of families in which members of each generation develop bipolar disorder found that those with the illness have a somewhat different genetic makeup than those who do not get ill. However, the reverse is not true: Not everybody with the genetic makeup that causes vulnerability to bipolar disorder will have the illness. Apparently additional factors, possibly stresses at home, work, or school, are involved in its onset.

In some families, major depression also seems to occur generation after generation. However, it can also occur in people who have no family history of depression. Whether inherited or not, major depressive disorder is often associated with changes in brain structures or brain function.

People who have low self-esteem, who consistently view themselves and the world with pessimism or who are readily overwhelmed by stress, are prone to depression. Whether this represents a psychological predisposition or an early form of the illness is not clear.

In recent years, researchers have shown that physical changes in the body can be accompanied by mental changes as well. Medical illnesses such as stroke, a heart attack, cancer, Parkinson's disease, and hormonal disorders can cause depressive illness, making the sick person apathetic and unwilling to care for his or her physical needs, thus prolonging the recovery period. Also, a serious loss, difficult relationship, financial problem, or any stressful (unwelcome or even desired) change in life patterns can trigger a depressive episode. Very often, a combination of genetic, psychological, and environmental factors is involved in the onset of a depressive disorder. Later episodes of illness typically are precipitated by only mild stresses, or none at all.

There are several types of antidepressant medications used to treat depressive disorders. These include newer medications—chiefly the selective serotonin reuptake inhibitors (SSRIs)—the tricyclics, and the monoamine oxidase inhibitors (MAOIs). The SSRIs—and other newer medications that affect neurotransmitters such as dopamine or norepinephrine—generally have fewer side effects than tricyclics. Sometimes the doctor will try a variety of antidepressants before finding the most effective medication or combination of medications. Sometimes the dosage must be increased to be effective. Although some improvements may be seen in the first few weeks, antidepressant medications must be taken regularly for 3 to 4 weeks (in some cases, as many as 8 weeks) before the full therapeutic effect occurs.

Patients often are tempted to stop medication too soon. They may feel better and think they no longer need the medication. Or they may think the medication isn't helping at all. It is important to keep taking medication until it has a chance to work, though side effects (see section on Side Effects on page 13) may appear before antidepressant activity does. Once the individual is feeling better, it is important to continue the medication for at least 4 to 9 months to prevent a recurrence of the depression. Some medications must be stopped gradually to give the body time to adjust. Never stop taking an antidepressant without consulting the doctor for instructions on how to safely discontinue the medication. For individuals with bipolar disorder or chronic major depression, medication may have to be maintained indefinitely.

Antidepressant drugs are not habit-forming. However, as is the case with any type of medication prescribed for more than a few days, antidepressants have to be carefully monitored to see if the correct dosage is being given. The doctor will check the dosage and its effectiveness regularly.

For the small number of people for whom MAO inhibitors are the best treatment, it is necessary to avoid certain foods that contain high levels of tyramine, such as many cheeses, wines, and pickles, as well as medications such as decongestants. The interaction of tyramine with MAOIs can bring on a hypertensive crisis, a sharp increase in blood pressure that can lead to a stroke. The doctor should furnish a complete list of prohibited foods that the patient should carry at all times. Other forms of antidepressants require no food restrictions.

Medications of any kind—prescribed, over-the counter, or borrowed—should never be mixed without consulting the doctor. Other health professionals who may prescribe a drug—such as a dentist or other medical specialist—should be told of the medications the patient is taking. Some drugs, although safe when taken alone can, if taken with others, cause severe and dangerous side effects. Some drugs, like alcohol or street drugs, may reduce the effectiveness of antidepressants and should be avoided. This includes wine, beer, and hard liquor. Some people who have not had a problem with alcohol use may be permitted by their doctor to use a modest amount of alcohol while taking one of the newer antidepressants.

Antianxiety drugs or sedatives are not antidepressants. They are sometimes prescribed along with antidepressants; however, they are not effective when taken alone for a depressive disorder. Stimulants, such as amphetamines, are not effective antidepressants, but they are used occasionally under close supervision in medically ill depressed patients.