Depression, in the context of one's psychological state of mind, is a loan word from the medical field. When some one's nervous system is, 'depressed,' for example, it means their heart rate is slower, and their breathing is slower, and perhaps their metabolism is slower.
Psychiatry has borrowed this word and repurposed it, to describe people who seem to be in a state of persistent despair; or what some tribal peoples have called, "permanent sadness."
A psychiatrist simply diagnoses, 'depression,' based on matching observable traits, or through oral self explanation, to criteria listed in the DSM-V or whatever book they are using now.
However, in my personal opinion, a persistent state of despair can have many causes, and manifest in many different ways. Some people have a very emotionally rich sadness, while others, may feel very emotionally numb and empty. Apathy seems to be quite prevalent in persistent sadness, yet, others produce some of their best work when they are morbidly melancholy; they are sort of the tortured artists.
A minor persistent despair may be simply, being stuck in a rut. While others seem to have seasonal or rhythmic bouts of melancholy/sadness/despair/depressed mood.
But where we are concerned with the word, 'depression,' we are talking about a medical loan word, adopted by psychiatry, that describes individuals who match a particular criteria; and from there, the psychiatrist has various recommended courses of drug therapy at his disposal.
A persistent low mood, may have physical causes, environmental causes, it may be related to past experiences, loss, it could be hormonal. There are a variety of different possible causes; and there are reported cases of permanently overcoming this state of mind.
There are self reported cases of people curing themselves, by, reaching a sort of cathartic point, where they have a profound realization, and just drop the whole thing and burst out of the gate into the race.
Other's swear by their anti-depressents, while others lament ever having taken them at all.
Other's go on to do some major soul searching, and finally happen about a group, notion, and/or idea, or cultural facet that sort of, 'wakes them up,' out of the fog, slowly, as if from a long slumbering dream.
It's a very interesting phenomena; and more interesting are the stories people have about how they escaped it, overcame it, or moved on it from, etc..
