Depression is defined as a mental illness in which a person experiences deep, unshakable sadness and diminished interest in nearly all activities. The term depression is used to describe the temporary sadness, loneliness, or blues that everyone feels from time to time. Depression is one of the most common mental illnesses. The illness affects all people, regardless of sex, race, ethnicity, or socioeconomic standing. Women are two to three times more likely than men to suffer from depression.
Some depression seems to come out of the blue, even when things are going well. Others seem to have an obvious cause such as a marital conflict, financial difficulty, or some personal failure. Most psychologists believe depression results from an interaction between stressful life events and a person’s biological and psychological vulnerabilities. Depression runs in families also. 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. Studies have shown that certain brain chemicals called neurotransmitters play an important role in regulating moods and emotions. Neurotransmitters involved in depression include nor epinephrine, dopamine, and serotonin. Studies have also suggested a 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 (cortical), a hormone secreted by the adrenal gland in response to stress. In addition, an underactive or overactive thyroid gland can lead to depression.
Depression can take several other forms. In bipolor disorder, a person’s mood swings back and forth between depression and mania. People with seasonal affective disorder
Bibliography: Microsoft Encarta Online Encyclopedia 2003 “Depression (psychology)” http://encarta.msn.com 1997-2003 Microsoft Corporation. Depression http://health.discovery.com/convergence/fires/depression.html Depression Central http://www.psycom.net/depression.central.html National Foundation for Depressive Illness http://www.depression.org/