depression

In medicine, an emotional state characterized by sadness, unhappy thoughts, apathy, and dejection. Sadness is a normal response to major losses such as bereavement or unemployment. After childbirth, postnatal depression is common. Clinical depression, which is prolonged or unduly severe, often requires treatment, such as antidepressant medication, cognitive therapy, or, in very rare cases, electroconvulsive therapy (ECT), in which an electrical current is passed through the brain.

Periods of depression may alternate with periods of high optimism, over-enthusiasm, and confidence. This is the manic phase in a disorder known as manic depression or bipolar disorder. A manic depressive state is one in which a person switches repeatedly from one extreme to the other. Each mood can last for weeks or months. Typically, the depressive state lasts longer than the manic phase.

Depression costs the USA around $12.4 billion each year in treatment. Another $23.8 billion is paid for by employers, arising from absenteeism and lost productivity. The National Institute of Mental Health estimated in 1998 that 17-20 million adults have a clinical depression each year and that depression will affect one in every five women and one in every ten men during their lifetimes.

Since 1990, the USA has held an annual National Depression Screening Day with free screening tests for depression and post-traumatic stress disorder (PTSD) given at some 1,750 sites around the nation and by 1,400 other doctors. The event had an added significance in 2001, coming exactly one month after the 11 September terrorist attacks on the USA. Symptoms have to continue for a full month to qualify for a diagnosis of PTSD.

In 1996, US researchers identified a connection between depression in women and low bone density, leading to an increased risk of fractures in later life. This is possible due to the increased levels of the steroid hydrocortisone during depressive periods.