Depression Terms Listed Alphabetically

Three Types of Depression

The three main categories of depression are major depression, dysthymia, and bipolar depression (sometimes referred to as manic depression).

Major depression affects 15 percent of Americans at one point during their lives, according to the U.S. Department of Health and Human Services. Its effects can be so intense that things like eating, sleeping, or just getting out of bed become almost impossible.

Major depression "tends to be a chronic, recurring illness," Laughren explains. Although an individual episode may be treatable, "the majority of people who meet criteria for major depression end up having additional episodes in their lifetime."

Unlike major depression, dysthymia doesn't strike in episodes, but is instead characterized by milder, persistent symptoms that may last for years. Although it usually doesn't interfere with everyday tasks, victims rarely feel like they are functioning at their full capacity. According to the National Alliance for the Mentally Ill, almost 10 million Americans may experience dysthymia each year.

Finally, bipolar disorder cycles between episodes of major depression and highs known as mania. Bipolar disorder is much less common than the other types, afflicting about 1 percent of the U.S. population. Symptoms of mania include irritability, an abnormally elevated mood with a decreased need for sleep, an exaggerated belief in one's own ability, excessive talking, and impulsive and often dangerous behavior.

Depression - Genes and Environment

Study after study suggests biochemical and genetic links to depression. A considerable amount of evidence supports the view that depressed people have imbalances in the brain's neurotransmitters, the chemicals that allow communication between nerve cells. Serotonin and norepinephrine are two neurotransmitters whose low levels are thought to play an especially important role. The fact that women have naturally lower serotonin levels than men may contribute to women's greater tendency to depression.

Family histories show a recurrence of depression from generation to generation. Studies of identical twins confirm that depression and genes are related, finding that if one twin of an identical pair suffers from depression, the other has a 70 percent chance of developing the disease. For fraternal twins or siblings, the rate is just 25 percent.

Environmental factors, however, may also play a role in depression. When combined with a biochemical or genetic predisposition, life stressors (such as relationship problems, financial difficulties, death of a loved one, or medical illness) may cause the disease to manifest itself.

John (not his real name), 25, was diagnosed with depression for the first time last year when he and his girlfriend ended their three-year relationship. "I couldn't do anything because I was totally absorbed with the whole break-up issue," he says. "It was impossible for me to sleep, and I would wake up at 3 or 4 in the morning and literally shake. And when it was time to wake up, I just couldn't get out of bed."

In addition, substance abuse and side effects from prescription medication may also lead to a depressive episode. And research shows that people battling serious medical conditions are especially prone to depression. According to the U.S. Department of Health and Human Services, those who have had a heart attack, for example, have a 40 percent chance of being depressed.

Seasonal affective disorder, often called "SAD," is a striking example of an environmental factor playing a major role in depression. SAD usually starts in late fall, with the decrease in daylight hours and ends in spring when the days get longer.

The symptoms of SAD, which include energy loss, increased anxiety, oversleeping, and overeating, may result from a change in the balance of brain chemicals associated with decreased sunlight. The exact reason for the association between light and mood is unknown, but research suggests a connection with the sleep cycle. Several studies have suggested that light therapy, which involves daily exposure to bright fluorescent light, may be an effective treatment for SAD.

Depression - Diagnosing the Disease

Medical professionals generally base a diagnosis of depressive disorder on the presence of certain symptoms listed in the American Psychiatric Association's Diagnostic and Statistical Manual. The DSM (presently in the fourth edition) lists the following symptoms for depression:

The diagnosis depends on the number, severity and duration of these symptoms. Even with this list of symptoms, diagnosing depression is not simple. According to the National Alliance for the Mentally Ill, it takes an average of eight years from the onset of depression to get a proper diagnosis.

In making a diagnosis, a health professional should also consider the patient's medical history, the findings of a complete physical exam, and laboratory tests to rule out the possibility of depressive symptoms resulting from another medical problem.

The symptoms of the depressive part of bipolar disorder are the same as those expressed in major (unipolar) depression. Because of the similarities in symptoms and the fact that manic episodes usually don't appear until the mid-20s, some people with bipolar disorder may mistakenly be diagnosed with unipolar depression. This may lead to improper treatment because antidepressants carry the risk of triggering a manic episode. (For information about treating bipolar disorder, see "Evening Out the Ups and Downs of Manic-Depressive Illness" in the June 1996 FDA Consumer.)

Antidepressant Drugs for Depression

One major approach for treating depression is the use of antidepressant medications. The older antidepressants include tricyclic antidepressants such as Tofranil (imipramine) and monoamine oxidase inhibitors such as Nardil (phenelzine). Antidepressants approved more recently include the selective serotonin reuptake inhibitors Prozac, Paxil and Zoloft, and the other newer antidepressants Wellbutrin, Effexor, Serzone, and Remeron.

The effects of antidepressants on the brain are not fully understood, but there is substantial evidence that they somehow restore the brain's chemical balance. These medications usually can control depressive symptoms in four to eight weeks, but many patients remain on antidepressants for six months to a year following a major depressive episode to avoid relapse.

Different drugs work for different people, and it is difficult to predict which people will respond to which drug or who will experience side effects. So it may take more than one try to find the appropriate medication.

Since the mid-1950s, tricyclic antidepressants have been the standard against which other antidepressants have been measured. Monoamine oxidase inhibitors were discovered around the same time as tricyclic antidepressants, but were prescribed less because, if mixed with certain foods or medications, the drugs sometimes resulted in a fatal rise in blood pressure.

Laughren describes Prozac as the "first of a new type of more selective antidepressants." The older antidepressants had unpleasant and sometimes dangerous side effects, such as insomnia, weight gain, blurred vision, sexual impairment, heart palpitations, dry mouth, and constipation. Prozac, other selective serotonin reuptake inhibitors, and other recently approved antidepressants have had generally safer side effect profiles.

A recent study funded by NIMH suggested that Prozac may be as effective in treating children and teens as adults, but the drug is not yet approved by FDA for use in this population.

Other types of therapy, such as natural substances extracted from plants, are currently being studied. Although not approved by FDA, some people believe St. John's wort, for example, is extremely helpful in alleviating their depressive symptoms. (See "An Herbal Alternative?")

When people are unresponsive to antidepressant medications or can't take them because of their age or health problems, electroconvulsive therapy (ECT), or "shock therapy," can offer a lifesaving alternative. Like antidepressants, ECT is believed to affect the chemical balance of the brain's neurotransmitters.

Before ECT, the patient is given anesthesia and a muscle relaxant to prevent injury or pain. Then electrodes are placed on the person's head, and a small amount of electricity is applied. This procedure is usually done three times a week until the patient improves. Some patients may experience a temporary loss of short-term memory.