7 minute read


An emotional state or mood characterized by one or more of these symptoms: sad mood, low energy, poor concentration, sleep or appetite changes, feelings of worthlessness or hopelessness, and thoughts of suicide.

Depression may signify a mood, a symptom, or a syndrome. As a mood, it refers to temporary feelings of sadness, despair, and discouragement. As a symptom, it refers to these feelings when they persist and are associated with such problems as decreased pleasure, hopelessness, guilt, and disrupted sleeping and eating patterns. The entire syndrome is also referred to collectively as a depression or depressive disorder. At any given time about 10 percent of all people suffer some of the symptoms of depression at an economic cost of more than $30 billion annually and costs in human suffering that cannot be estimated. The American Psychiatric Association estimates that about one in five Americans experiences an episode of depression at least once in his or her lifetime.

Depression can generally be traced to a combination of physical, psychological, and environmental factors. Depressive disorders involve a person's body, mood and thoughts.

Genetic inheritance makes some people more likely than others to suffer from depression. More than 60 percent of people who are treated for depression have family members who have been depressed at some time, and there is a 15 percent chance that immediate biological relatives of a depressed person will develop depression. Twin studies have also supported the existence of a genetic predisposition to depression, particularly bipolar depression. Researchers have found that depression is associated with changes in brain chemistry. The normal balance and functioning of two neurotransmitters in particular—serotonin and norepinephrine—appear to be disrupted in depressed persons, a finding that has led to the development of a variety of antidepressant drugs. Depression is also associated with an imbalance of cortisol, the main hormone secreted by the adrenal glands. Other physiological factors sometimes associated with depression include viral infections, low thyroid levels, and biological rhythms, including women's menstrual cycles— depression is a prominent symptom of premenstrual syndrome (PMS).

Life events, including developmental traumas, physical illness, problems in intimate relationships, and losses may trigger a depression. According to classic psychoanalytic theory, depression is the result of losing someone through death or abandonment and turning one's feelings of anger and resentment inward. For behaviorists, the link between such negative events as the death of a loved one, the end of a relationship, or the loss of a job is the removal of a source of reward. Cognitive theorists claim that depressed people develop destructive ways of thinking, which include blaming themselves when things go wrong, focusing on the negative side of events, and habitually jumping to excessively pessimistic conclusions.

Another psychological explanation of depression centers on the concept of learned helplessness, a phenomenon first observed in a laboratory setting when animals that had no control over their situations (such as changing their situation by pressing a lever) showed signs of depression. It has been found that lack of control over their own lives is also associated with depression in humans and may be especially relevant to depression in women, whose incidence of depression is twice that of men. Another factor that may be linked to depression in women is the tendency to dwell on negative events, a cognitive style that research has shown to be more common among women than among men, who are more likely to distract themselves from negative feelings by engaging in various forms of activity.

The Diagnostic and Statistical Manual (DSM) of Mental Disorders, produced by the American Psychiatric Association, categorizes depression as an affective, or mood, disorder. The DSM criterion for clinical depression is the presence of at least five of the following symptoms almost every day for at least two weeks: depressed mood; loss of interest in activities; significant changes in appetite or weight; disturbed sleep patterns; agitated or slowed movements; fatigue; feelings of worthlessness or inappropriate guilt; trouble concentrating; and preoccupation with death or suicide. In a major depressive episode, these symptoms can persist for six months or longer without treatment. Usually, major depression first occurs in one's late twenties. In severe cases, people may be almost completely incapacitated, losing the ability to work, socialize, and even care for themselves. The depressive episode may eventually lift completely, or some symptoms may persist for as long as two years. More than half the people who suffer from major depression experience more than one episode. A serious complication of major depression is the threat of suicide. Some 60 percent of people who commit suicide are depressed, and 15 percent of those diagnosed with depression eventually commit suicide.

In dysthymia, a less severe form of depression, the symptoms are more prolonged but not disabling. Depressed mood is the major symptom. The depressed mood lasts at least two years for adults and one year for children with two or more of the other symptoms of clinical depression present. Bipolar disorder (manic depression) is characterized by the alternation of depression and mania, an overly elated, energetic state. Characteristic symptoms of mania include an inappropriately cheerful mood; inflated optimism and self-esteem; grandiose notions; excessive energy with a decreased need for sleep; racing thoughts; increased talking; and irritability when confronted by obstacles or opposition. During manic episodes, people characteristically use poor judgment, make irrational decisions and may even endanger their own lives. In bipolar disorder, manic episodes lasting days, weeks, or even months, alternate with periods of depression. There may be a period of normalcy between the two or an immediate mood swing from one mode to the other.

Cyclothymic disorder, the bipolar equivalent of dysthymia, resembles bipolar disorder but consists of a less extreme pattern of mood swings. Another type of depression, seasonal affective disorder (SAD), follows an annual cycle triggered by seasonal variations in light and usually involves depression during the winter months; it is thought to be due to an excess of the sleep-inducing hormone melatonin. Sometimes depressions become severe enough and include features of psychosis. These cases— which account for about 10 percent of all clinical depressions—are characterized by delusions or hallucinations and an especially high incidence of suicide.

Most people with clinical depression do not recognize that they have it and fail to seek treatment, blaming stress or physical ailments for their lack of well-being. Of those who do seek treatment either through psychotherapy, medication, or a combination of both, 80 percent improve, often within a matter of weeks. Psychotherapy alone is generally more effective for people with mild or moderate depression, while medication is advised for those whose depression is more severe or who have developed physical symptoms. Most persons receiving psychotherapy for their depression undergo short-term treatment lasting between 12 and 16 weeks. Treatment methods vary among g different schools of therapy and individual therapists. Cognitive behavior therapy focuses on helping patients identify and change negative thought patterns; interpersonal and family therapies emphasize strategies for improving one's relationships with others; and behavioral therapy involves monitoring one's actions and modifying them through a system of incentives and rewards.

Two types of medication traditionally used to treat depression—tricyclic antidepressants and monoamine oxidase (MAO) inhibitors—increase the brain's supply of certain neurotransmitters, including norepinephrine and dopamine. Both medications are effective for many patients but can cause a variety of side effects, particularly MAO inhibitors. In recent years a new generation of antidepressants has been developed that affects levels of serotonin rather than norepinephrine. Among these selective serotonin reuptake inhibitors (SSRIs) is fluoxetine (Prozac), the most widely used antidepressant in the United States. It is effective in 60 to 80 percent of those who take it and has fewer side effects than previous types of antidepressants. Other SSRIs prescribed include sertraline (Zoloft) and paroxetine (Paxil). Lithium for many years has been used to treat manic episodes in persons with bipolar disorder. Other medications found to help control mood swings are: carbamazepine, which has gained wide acceptance in clinical practice, and valproate, approved by the Food and Drug Administration for first-line treatment of acute mania.

Whenever possible, persons suffering from depression should be urged to seek treatment through a private therapist, clinic, or hospital. There are special treatment centers for depression at medical centers throughout the country. A complete physical examination by a family physician or internist is the first step in getting appropriate treatment. Since certain medications and medical conditions, such as a viral infection, can cause depression-like symptoms, a physician can rule out these possibilities first.

Further Reading

Persons, Jacqueline B. Essential Components of Cognitive-Behavior Therapy for Depression. Washington, D.C.: American Psychological Association, 2000.

Sholevar, G. Pirooz. The Transmission of Depression in Families and Children: Assessment and Intervention. Northvale, N.J.: Aronson, 1994.

Volkan, Vamik D. Depressive states and their treatment. Northvale, N.J.: J. Aronson, 1994.

Additional topics

Psychology EncyclopediaPsychological Dictionary: Kenneth John William Craik Biography to Jami (Mulla Nuruddin ʼAbdurrahman ibn-Ahmad Biography