Depression reveals itself in two major forms - Reactive and Endogenous.
Reactive depression is when feelings run the gamut between emotional sadness triggered by a minor event to great sadness at the loss of someone close to you. Depression that is Endogenous is one that continues with no seeming reason for feeling this way. Sometimes an imbalance in chemicals causes this condition.
The physical symptoms of this disorder include sadness, emptiness, withdrawal from others, irritability, emotional sensitivity, low motivation and self-esteem, and suicidal thoughts (to name a few).
Depression of the Spirit
There is yet another form of this mood disorder which is called spiritual depression. Existing as a state of mind, it can come to people when God seems far away or not listening to them. In this state of mind they have lost their zeal for God and the Bible. They seem to grow tired of doing good to others (Galatians 6:9, 2Thessalonians 3:13) and ready to give up under the weight of their feelings.
There are cases in the Bible where spiritual depression seems to have occurred. King David often found himself spiritually depressed and in need of God, as he states in Psalm 42.
Why am I so sad? Why am I so troubled? (verse 5)
David repeats a version of verse 5 again and again. He soul longs for God. He states he knows he mourns (Psalm 42:9) where he feels:
He has sent waves of sorrow over my soul; chaos roars at me like a flood (Psalm 42:7)
It all seems too much for him to bear. There is also the example of Elijah the prophet. God through Elijah had a monumental victory over the 450 pagan priests of Baal at Mount Carmel (1Kings 19). All the false prophets were killed and Israel's heart turned back to worshipping the true God. Jezebel, the wife of King Ahab, heard what happened and sent word to Elijah that she would make sure he would be dead within a day. When he heard the threat, even after the awesome miracle of Carmel, Elijah decided to run for his life! Traveling to Mount Horeb he laments to God:
"But he himself (Elijah) went a day’s journey into the wilderness, and came and sat down under a broom tree. And he prayed that he might DIE, and said, 'It is enough! Now, Lord, take my life, for I am no better than my fathers!' " (1Kings 19:4)
Elijah also laments that he is the only prophet of God left alive. God's "cure" was to get him busy again doing His will. He was also told that he was NOT the only righteous man left in Israel! There is also the well-known case of Judas Iscariot. After betraying Jesus to those who hated him he had a dramatic change of heart. His depressed state and remorse was so severe that it drove him to commit the ultimate expression of self-hate - suicide.
5 Then he threw down the pieces of silver in the temple and departed, and went and hanged himself. (Matthew 27)
A possible cure
There are a growing number of psychologists who believe that one of the main causes of depression (which would also apply to the kind that is spiritual) is negative, demanding and pessimistic thinking. This type of "stinking thinking" helps create an attitude of low self-worth and self-esteem. The 'cure' therefore, for certain types of this disease, and possibly for the spiritual type, is postive reinforcing self-talk.