Everyone has days where they feel blah, down, or sad. Typically, these feelings disappear after a day or two, particularly if circumstances change for the better. People experiencing the temporary "blues" don't feel a sense of crushing hopelessness or helplessness, and are able, for the most part, to continue to engage in regular activities. Prolonged anhedonia (the inability to experience pleasure), hopelessness, and failure to experience an increase in mood in response positive events rarely accompany "normal" sadness. The same may be said for other, more intense sorts of symptoms such as suicidal thoughts and hallucinations (e.g., hearing voices). Instead, such symptoms suggest that serious varieties of depression may be present, including the subject of this document: Major Depressive Disorder (MDD) or (more informally), Major Depression.

For people dealing with Major Depression, negative feelings linger, intensify, and often become debilitating.

Major Depression is a common yet serious medical condition that affects both the mind and body. It is a complex illness, creating physical, psychological, and social symptoms. Although informally, we often use the term "depression" to describe general sadness, the term Major Depression is defined by a formal set of criter...