Most depression is a reaction to an unhappy event. It is natural to have some depression after a loss such as the death of a relative, or after a major disappointment at home or at work.
Depression is more prevalent in women than men and is especially common among adolescents.
Mild depression comes and goes and is characterized by downheartedness, sadness, and dejection. Noticeably disturbed thought processes, poor communication and socialization, and sensory dysfunction indicate moderate depression. People with severe depression are withdrawn, without expression, indifferent toward their surroundings, and may show signs of delusional thinking and limited physical activity . There may be other causes of depression. This list is not all inclusive, and the causes are not presented in order of likelihood.