Depression (psychology)

B

Changes in Energy Level

Depression also changes one’s energy level. Some depressed people may be restless and agitated, engaging in fidgety movements and pacing. Others may feel sluggish and inactive, experiencing great fatigue, lack of energy, and a feeling of being worn out or carrying a heavy burden. Depressed people may also have difficulty thinking, poor concentration, and problems with memory.

C

Poor Self-Esteem

People with depression often experience feelings of worthlessness, helplessness, guilt, and self-blame. They may interpret a minor failing on their part as a sign of incompetence or interpret minor criticism as condemnation. Some depressed people complain of being spiritually or morally dead. The mirror seems to reflect someone ugly and repulsive. Even a competent and decent person may feel deficient, cruel, stupid, phony, or guilty of having deceived others. People with major depression may experience such extreme emotional pain that they consider or attempt suicide. At least 15 percent of seriously depressed people commit suicide, and many more attempt it.

D

Psychotic Symptoms

In some cases, people with depression may experience psychotic symptoms, such as delusions (false beliefs) and hallucinations (false sensory perceptions). Psychotic symptoms indicate an especially severe illness. Compared to other depressed people, those with psychotic symptoms have longer hospital stays, and after leaving, they are more likely to be moody and unhappy. They are also more likely to commit suicide. See Psychosis.

IV

Causes

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.

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A

Biological Factors

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 deficiences in vitamin B₆, vitamin B₁₂, and folic acid (see Vitamin); degenerative neurological disorders, such as Alzheimer’s disease and Huntington’s disease (see Chorea); 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.

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