Depression

Depression is a disorder characterized by depressed mood or loss of interest or pleasure in usual activities. Depression is a general term that has been used to describe transient feelings, a psychological disorder, and a health problem that is characterized by a group of related symptoms (Beeber, 1998). "Depression is an alteration in mood probably treated more by nurse psychotherapists more frequently than any other symptom in clinical practice with the exception of anxiety" (Drake, Drake, & Price, 1996, p. 30).

Some depressions seem to come out of the blue, even when things are going well. Others seem to have an obvious cause: a marital conflict, financial difficulty, or some personal failure. Yet many people with these problems do not become deeply depressed. Most psychologists believe depression results from an interaction between stressful life events and a person's biological and psychological vulnerabilities. According to Cognitive Therapy of Depression, "depression is not something one has; it is something that is happening in a person in relation to others" (Draghi & Flach, 1975, p. 45). Depression runs in families. By studying twins, researchers have found evidence of a strong genetic influence in depression. Genetically identical twins raised in the same environment are three times more likely to have depression in common than fraternal twins, who have only about half of their genes in common. In addition, identical twins are five times more likely to have bipolar disorder in common. These findings suggest that vulnerability to depression and bipolar disorder can be inherited. Adoption studies have provided more evidence of a genetic role in depression. These studies show that children of depressed people are vulnerable to depression even when raised by adoptive parents.

Genes may influence depression by causing abnormal activity in the brain. Studies have shown that certain brain chemicals called neurotransmitters play an important role in regulating moods and emotions. Neurotransmitters involved in depression include norepinephrine, dopamine, and serotonin. Research in the 1960s suggested that depression results from lower than normal levels of these neurotransmitters in parts of the brain. Support for this theory came from the effects of antidepressant drugs, which work by increasing the levels of neurotransmitters involved in depression. However, later studies have discredited this simple explanation and have suggested a more complex relationship between neurotransmitter levels and depression.

An imbalance of hormones may also play a role in depression. Many depressed people have higher than normal levels of hydrocortisone (cortisol), a hormone secreted by the adrenal gland in response to stress. In addition, an underactive or overactive thyroid gland can lead to depression.

A variety of medical conditions can cause depression. These include dietary deficiencies in vitamin B6, vitamin B12, and folic acid; degenerative neurological disorders, such as Alzheimer's disease and Huntington's disease; strokes in the frontal part of the brain; and certain viral infections, such as hepatitis and mononucleosis. Certain medications, such as steroids, may also cause depression.

Psychologists agree that stressful experiences can trigger depression in people who are predisposed to the illness. For example, the death of a loved one may trigger depression. Psychologists usually distinguish true depression from grief, a normal process of mourning a loved one who has died. Other stressful experiences may include divorce, pregnancy, the loss of a job, and even childbirth. About 20 percent of women experience an episode of depression, known as postpartum depression, after having a baby. In addition, people with serious physical illnesses or disabilities often develop depression. Sullivan saw depression as a way of dealing with anxiety, that depression was more tolerable than the anxiety itself (anxiety is a response to feeling disapproval from someone else) (Draghi & Flach, 1975).

Most people with depression respond to antidepressant drugs. Antidepressants have been a significant benefit in the treatment of depression (Beck, Enery, Rush, & Shaw, 1979). These medications appear to work by altering the levels of serotonin, norepinephrine, and