Depression

History

Depressive disorders have called attention of people since ancient times. The papyrus of Ebers contains perhaps one of the earliest descriptions of clinical depression and the symptoms leading to the suicide of the Greek hero Ajax, described in Homer's Iliad, is such a good depiction of a depressive disorder that it must have been based on real observations. Depression may also trace its roots to melancholia, a term used in ancient medicine to describe a predominance of black bile, one of the “four humors” postulated by Galen. The theory of the four humors postulated that there was need for equilibrium between those humors in the human body, and the excess of one of them would cause disease. When the black bile (melancholia in Greek) predominated, symptoms compatible with modern depression disorders arose. It is interesting to note that the modern theory of depressive disorders somehow resembles the idea of unbalanced humors: depression started to be explained by observations in the 1950s that drug-induced changes on neurotransmitter levels affected depressive symptoms, prompting the conclusion that depression was caused by an imbalance in the levels of neurotransmitters, still considered the pathophysiological basis of depressive disorders.

Prevalence

About 16 percent of the world population is affected by a form of depression on at least one occasion in their lives and the mean age of onset is in the late 20s. Some countries report a considerably higher incidence of depression, such as Australia, where the incidence of depression in women can reach 25 percent.

Women appear to be at a higher risk for depression, but this is decreasing and there seems to be no gender difference in the elderly. One important point is that there may be an underestimation of the incidence of depression in men; due to cultural factors, men are less likely to complain of depressive symptoms and even less likely to seek and accept treatment for depression.

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