From Carl Zetie, Raleigh, North Carolina, US
As suggested, there may never be a unified theory of depression. The clinical successes and failures of a variety of different treatments may mean that more than one hypothesis is true, and what we now call depression is in fact a collection of different conditions sharing a cluster of similar symptoms.
Much like cancer has come to be recognised as a number of distinct but related conditions, the same might be true of depression.
