Depression can be induced by events in our lives...The following events have been very low times...

Fall of 2004 - Marriage falling apartment - hospitalized twice for certain thoughts
Christmas 2004 - left house - filed for divorce
October 2005 - Dad Diees
December 2005 - Divorce Official
January 2006 - Move back into house - ex moves to apartment no idea how to pay 1st and 2nd mortgage
May 2006 - find roommate
July 2006 - loose job 30 day notice
Aug 2006 - new job - new company picked me up still doing same job just new company.

Anyway - Depression can be event driven...