Not a single aspect of the human condition escapes them, not one element of human behaviour avoids their grip. When this grip tightens we have melancholia - otherwise, we suffer from a mere depression. A depression is a depression is a depression no matter what its precipitating causes are or in which stage it appears. Patterns change or are eliminated altogether. The misleading thing is that depression does not entail a change in the mood.
Depression is very much like life itself - difficult to define, though easily recognizable.
It can happen at any age, to anyone, with or without an anteceding stressful event. It can set on gradually or erupt dramatically. The earlier it occurs - the more likely it is to recur. This apparently arbitrary and shifting nature of depression only enhances the guilt attribution feelings of the patient. This is a vicious and self-fulfilling prophetic cycle.